Overview of Multicellular Organism Biology

1. Overview The levels of organization in multicellular organisms starting with atoms and ending with organisms: Atoms – The basic units of matter (e.g., carbon, hydrogen, oxygen) that form all substances. Molecules – Atoms bonded together (e.g., water, proteins, DNA) to perform chemical functions. Organelles – Specialized structures within cells made of molecules (e.g., mitochondria, nucleus) that carry out specific cellular functions. Cells – The basic structural and functional units of life; in multicellular organisms, different types of cells have different roles (e.g., muscle cells, nerve cells). Tissues – Groups of similar cells working together to perform a specific function (e.g., epithelial tissue, muscle tissue). Organs – Structures composed of different types of tissues working together (e.g., heart, lungs, brain). Organ Systems – Groups of organs that work together to carry out major body functions (e.g., digestive system, nervous system). Organism – The complete living being made up of various organ systems working together to maintain life (e.g., a human, a dog, a tree). Homeostasis is the process by which a living organism maintains a stable internal environment despite changes in external conditions. (Alternate definition: keeping the inside of the body balanced and stable, even when things outside change.) Organisms use feedback mechanisms to help keep their internal environment stable (homeostasis). There are two main types: negative feedback and positive feedback. 1. Negative feedback – This is the most common way the body maintains balance. When something in the body changes too much, negative feedback works to bring it back to normal. * Example: If your body gets too hot, you start to sweat to cool down. 2. Positive feedback – This type of feedback increases a change instead of stopping it. It pushes the body further in the same direction, but only for a short time, usually to complete a process. * Example: During childbirth, hormones keep increasing to help the muscles contract until the baby is born. B. The Metric System State the basic units of the metric system for length, mass, time and volume. Length – Meter (m) Mass – Gram (g) Time – Second (s) Volume – Liter (L) Identify the fraction or multiple associated with each of the following prefixes: kilo, deci, centi, milli, micro, and nano. * Kilo (k) = 1,000 (10³) * Deci (d) = 1/10 (0.1 or 10⁻¹) * Centi (c) = 1/100 (0.01 or 10⁻²) * Milli (m) = 1/1,000 (0.001 or 10⁻³) * Micro (µ) = 1/1,000,000 (0.000001 or 10⁻⁶) * Nano (n) = 1/1,000,000,000 (0.000000001 or 10⁻⁹) Combine the prefixes above with a metric unit and know the correct abbreviation of the combined prefix and unit. Convert quantities between the metric units. Steps to Convert Between Units: 1. Find the starting and target units. 2. Count the number of steps between them on the metric scale. 3. Move the decimal point that many places—to the right if converting to a smaller unit, to the left if converting to a larger unit. C. Atoms, Molecules, Bonds and Properties of Matter 1. Define the term element. An element is a pure substance made of only one type of atom. 2. Common chemical symbols: Oxygen – O Carbon – C Hydrogen – H Nitrogen – N Calcium – Ca Potassium – K Sodium – Na Chlorine – Cl Iron – Fe Phosphorus – P 3. Chemical Formulas * Carbon dioxide – CO₂ * Carbon monoxide – CO * Water – H₂O * Hydrochloric acid – HCl * Sodium chloride – NaCl * Glucose – C₆H₁₂O₆ * Sodium bicarbonate (sodium hydrogen carbonate) – NaHCO₃ 4. Define: Atom An atom is the smallest unit of an element that retains the properties of that element. It consists of a nucleus (with protons and neutrons) and electrons that orbit the nucleus. 5. Basic Structure of an Atom * Protons – Positively charged particles found in the nucleus * Neutrons – Neutral particles (no charge) found in the nucleus * Electrons – Negatively charged particles that orbit the nucleus in electron shells 6. Charge & Location * Protons – Positive (+), in the nucleus * Neutrons – Neutral (0), in the nucleus * Electrons – Negative (−), in electron clouds/orbitals around the nucleus 7. Define: Isotope An isotope is an atom of the same element (same number of protons) but with a different number of neutrons, resulting in a different atomic mass. 8. Isotopes in Medicine Isotopes are used in medical diagnosis and treatment, such as: * Radioactive iodine (I-131) for treating thyroid disorders * Technetium-99m for imaging organs * Carbon-14 for tracing metabolic pathways 9. Define: Molecule and Ion * Molecule – A group of atoms bonded together (e.g., H₂O, CO₂) * Ion – An atom or molecule with a net electrical charge due to loss or gain of electrons (e.g., Na⁺, Cl⁻) Electrons play a critical role in chemical bonding by being shared (in covalent bonds) or transferred (in ionic bonds). 10. Covalent vs. Ionic Bonds * Covalent bond: Atoms share electrons (e.g., H₂O, CO₂) * Ionic bond: Atoms transfer electrons, forming ions (e.g., NaCl) Diagrams: * Covalent: Lines between atoms (e.g., H–O–H) * Ionic: Often shown using charges (Na⁺ Cl⁻) 11. Bond Strength * Covalent bonds are generally stronger and require more energy to break. * Ionic bonds are also strong, especially in solid form, but can dissociate more easily in water. 12. Polar vs. Nonpolar Bonds * Polar bonds: Unequal sharing of electrons; one atom is more electronegative (e.g., H₂O) * Nonpolar bonds: Equal sharing of electrons (e.g., O₂, CH₄) Polar molecules: Have partial charges and interact with water Nonpolar molecules: Do not have partial charges and are generally hydrophobic 13. Type of Bond by Molecule * Carbon dioxide (CO₂) – Nonpolar covalent * Water (H₂O) – Polar covalent * Hydrochloric acid (HCl) – Polar covalent * Sodium chloride (NaCl) – Ionic * Oxygen gas (O₂) – Nonpolar covalent * Sodium bicarbonate (NaHCO₃) – Ionic (Na⁺ with bicarbonate ion), and covalent within HCO₃⁻ 14. Hydrogen Bond A hydrogen bond is a weak attraction between a hydrogen atom (already covalently bonded to a more electronegative atom like oxygen or nitrogen) and another electronegative atom. Characteristics: * Weak individually, but strong in large numbers * Essential in water properties and DNA structure 15. Hydrogen Bonds in Diagrams Hydrogen bonds are typically shown as dotted or dashed lines (e.g., H···O) between molecules. 16. Define: Matter and Mass * Matter: Anything that has mass and takes up space * Mass: The amount of matter in an object; not dependent on gravity 17. States of Matter * Solid – Definite shape and volume * Liquid – Definite volume, takes shape of container * Gas – No definite shape or volume, expands to fill space 18. Particle Motion by State * Solid – Tightly packed, vibrate in place * Liquid – Loosely packed, move past each other * Gas – Widely spaced, move freely and rapidly Temperature increases motion in all states. 19. Temperature, Pressure, and Volume (Closed System) * As temperature increases, particles move faster, increasing pressure (if volume is constant). * Increasing volume can lower pressure, and vice versa (if temperature is constant). * These relationships are described by gas laws (Boyle’s, Charles’, etc.). D. Water 1. Describe the Polarity of Water Water (H₂O) is a polar molecule because: * The oxygen atom is more electronegative than hydrogen, pulling shared electrons closer to itself. * This creates a partial negative charge (δ⁻) on oxygen and partial positive charges (δ⁺) on the hydrogens. * The molecule has a bent shape, not linear, which creates a dipole (a positive and negative end). This polarity allows water molecules to form hydrogen bonds with each other and with other polar molecules. 3. Biological Importance of Hydrogen Bonds * Between Water Molecules: * Create cohesion and surface tension * Give water its high boiling point and heat capacity * Essential for water transport in plants (cohesion + adhesion = capillary action) * Between Other Polar Covalent Molecules: * Stabilize the structures of proteins (e.g., α-helices and β-sheets) * Hold together strands of DNA (between nitrogenous bases: A–T, G–C) * Influence the 3D shape of enzymes and other biological molecules Hydrogen bonds are weak individually but strong collectively, making them ideal for temporary but crucial interactions in biological systems. This distinction is critical in cell membrane formation, where hydrophobic tails face inward and hydrophilic heads face outward in the phospholipid bilayer. E. Acids, Bases, pH, and Buffers 1. Definitions: Acid, Base, and Hydrogen Ion (Proton) * Acid: A substance that donates hydrogen ions (H⁺) (protons) in solution. * Base: A substance that accepts hydrogen ions (H⁺) or releases hydroxide ions (OH⁻) in solution. * Hydrogen ion (H⁺): A proton—a hydrogen atom that has lost its only electron, often simply written as H⁺. 3. Reading the pH Scale * 0–6: Acidic (e.g., lemon juice ~pH 2) * 7: Neutral (e.g., pure water) * 8–14: Basic (e.g., bleach ~pH 13) Every 1-unit change in pH = 10x change in H⁺ concentration. 5. Define: Buffer A buffer is a chemical system that resists changes in pH when small amounts of acid or base are added. 6. How Buffers Maintain Homeostasis * Buffers work by absorbing H⁺ or OH⁻ ions to keep the pH stable. * Example: The bicarbonate buffer system in blood: HCO₃⁻ + H⁺ ⇌ H₂CO₃ ⇌ CO₂ + H₂OHCO₃⁻ + H⁺ ⇌ H₂CO₃ ⇌ CO₂ + H₂O * Helps maintain blood pH around 7.35–7.45, which is crucial for proper cell function and enzyme activity. 7. Define: Dissociation Dissociation is the process where a molecule breaks apart into ions when dissolved in water. 8. Effect of Dissociation: Producing Anions and Cations * When compounds dissociate, they form: * Cations: Positively charged ions (e.g., Na⁺, H⁺) * Anions: Negatively charged ions (e.g., Cl⁻, OH⁻) Example: NaCl → Na⁺ + Cl⁻ 9. Dissociation and Acid/Base Strength * Strong acids/bases: Completely dissociate in water (e.g., HCl, NaOH) → more ions → stronger effect on pH * Weak acids/bases: Partially dissociate (e.g., acetic acid, NH₃) → fewer ions → weaker effect on pH 10. Characteristics of a Neutralization Reaction A neutralization reaction occurs when an acid and a base react to form: * Water (H₂O) and * A salt (ionic compound) General formula: Acid (H⁺) + Base (OH⁻) → H₂O + SaltAcid (H⁺) + Base (OH⁻) → H₂O + Salt Example: HCl + NaOH → H₂O + NaCl F. Chemical Reactions 2. Examples of Kinetic and Potential Energy * Kinetic Energy: * Muscle movement * Flowing blood * A moving car * Potential Energy: * Chemical bonds in glucose * Water held behind a dam * A compressed spring 3. Energy in Chemical Reactions (Organisms) * Organisms use chemical reactions to: * Break down compounds (e.g., glucose) → release energy (catabolic reactions) * Build new compounds (e.g., proteins, DNA) → require energy (anabolic reactions) * Cellular respiration breaks glucose to release ATP * Photosynthesis stores energy in glucose 4. Simple Chemical Reaction Example (Proper Notation) Example (cellular respiration simplified): C6H12O6+6O2→6CO2+6H2O+ATPC6H12O6+6O2→6CO2+6H2O+ATP (Reactants on the left, products on the right; arrow shows direction of reaction) 6. Chemical Equilibrium In a reversible reaction at equilibrium: * The rate of the forward reaction equals the rate of the reverse reaction * Concentrations of reactants and products stay constant, but reactions still occur 7. Definitions * Catalyst: Substance that speeds up a reaction without being consumed * Enzyme: A biological catalyst, usually a protein * Substrate: The specific reactant that an enzyme acts on * Products: The resulting molecules after the reaction * Activation Energy: The energy required to start a reaction * Active Site: The region of the enzyme where the substrate binds 8. Enzyme Characteristics * Specificity: Each enzyme works on one specific substrate (lock-and-key model) * Reusability: Enzymes are not used up or permanently changed in the reaction * Speed: They lower activation energy to speed up reactions * Conditions: Work best under specific pH and temperature; can be denatured if conditions are wrong 9. How Enzymes Work (Including Activation Energy and Reaction Rate) * Enzymes are biological catalysts—they speed up chemical reactions without being used up. * They work by lowering the activation energy needed for a reaction to begin. * Activation energy is the energy barrier that must be overcome for reactants to be converted into products. * The enzyme has an active site where the substrate binds, forming an enzyme-substrate complex. * Once the reaction occurs, the products are released, and the enzyme is free to be reused. 🔽 Effect of Enzymes: * Lower activation energy * Increase reaction rate * Do not alter the final products or equilibrium 10. Factors Affecting Enzyme Activity 🧪 pH: * Each enzyme has an optimal pH (e.g., pepsin in the stomach works best at pH 2). * If the pH is too high or too low, the enzyme’s shape (and active site) can be altered or denatured, reducing or stopping activity. 🌡️ Temperature: * Enzyme activity increases with temperature, up to an optimal point. * If the temperature gets too high, enzymes can denature, losing their shape and function. * If it's too cold, reactions slow down because molecules move more slowly and collide less often. G. Biomolecules 1. Why Carbon Is a Versatile Element Carbon is central to all biomolecules because of its unique bonding properties: * Has 4 valence electrons, allowing it to form 4 covalent bonds with other atoms. * Can form single, double, or triple bonds. * Can bond with many elements (e.g., H, O, N, P, S) and other carbon atoms, forming: * Chains, rings, and branches * This makes carbon the backbone of carbohydrates, lipids, proteins, and nucleic acids. 3. Define Monomer and Polymer * Monomer: A single subunit or building block (e.g., glucose, amino acid). * Polymer: A large molecule made of repeating monomers bonded together. Polymer Monomers Carbohydrates Monosaccharides Proteins Amino acids Nucleic acids Nucleotides Lipids (some, like triglycerides) Glycerol + fatty acids (not true polymers) 4. Reactions: Making and Breaking Polymers Reaction Type What It Does Description Dehydration synthesis (Condensation) Builds polymers Monomers bond together by removing a water molecule. Requires energy. Hydrolysis Breaks polymers Water is added to break bonds between monomers. Releases energy. Example: * Dehydration: Glucose+Glucose→Maltose+H2OGlucose+Glucose→Maltose+H2O * Hydrolysis: Maltose+H2O→Glucose+GlucoseMaltose+H2O→Glucose+Glucose CARBOHYDRATES: 5. Carbohydrate Terms and Structure * Monosaccharide: * The simplest carbohydrates; one sugar unit * Monomer of all larger carbohydrates * Example: Glucose * Disaccharide: * Made of two monosaccharides joined by dehydration synthesis * Example: Sucrose = Glucose + Fructose * Polysaccharide: * A polymer of many monosaccharides (hundreds to thousands) * Can be branched or unbranched * Example: Starch 7. Functions of Each Carbohydrate PROTEINS: 8. Amino Acids and Proteins * Amino acids are the monomers (building blocks) of proteins. * They link together by peptide bonds to form polypeptides (chains), which fold into proteins. 9. Parts of an Amino Acid Every amino acid has the same basic structure: * Central carbon atom (C) * Amino group (—NH₂) * Carboxyl group (—COOH) * Hydrogen atom (H) * R group (side chain that varies in each amino acid) 📌 The R group is what makes each of the 20 amino acids unique. 10. Role of the R Group * The R group determines: * Polarity (polar or nonpolar) * Charge (positive, negative, or neutral) * Hydrophobic or hydrophilic nature * Special structures (e.g., disulfide bonds from —SH in cysteine) * The R group influences how the protein folds and functions. 11. Four Levels of Protein Structure Level Description Bond Types Primary Sequence of amino acids Covalent peptide bonds Secondary Local folding into α-helices or β-pleated sheets Hydrogen bonds Tertiary 3D shape of the entire polypeptide Hydrogen, disulfide, ionic, and hydrophobic interactions Quaternary Combination of 2+ polypeptide chains Same as tertiary (non-covalent + covalent) 12. Importance of Shape to Protein Function * A protein’s shape (structure) determines its function. * If the shape is altered, the protein may lose its ability to bind to other molecules (e.g., enzymes, receptors, antibodies). 13. Definition of Denaturation * Denaturation is the unfolding or distortion of a protein’s 3D shape. * This process disrupts bonds (especially hydrogen bonds), but does not break the amino acid sequence. 14. Effect of Denaturation on Function * Denatured proteins lose their specific shape, and therefore can’t function properly. * Example: A denatured enzyme can’t bind to its substrate. 15. Effects of pH and Temperature on Protein Function * pH: Extremes can alter charges on amino acids and disrupt hydrogen/ionic bonds, leading to denaturation. * Temperature: High temps can cause increased molecular motion, breaking bonds and denaturing the protein. * Low temps slow function but don’t denature. 16. Examples of Protein Functions in Cells Function Example Enzymes Lactase, amylase (catalysts) Transport Hemoglobin (O₂ transport), membrane channels Structure Collagen (skin, connective tissue), keratin Defense Antibodies (immune system) Signaling Hormones like insulin Movement Actin, myosin (muscle contraction) NUCLEIC ACIDS: 17. Two Major Nucleic Acids in Cells * DNA (Deoxyribonucleic acid) * RNA (Ribonucleic acid) 18. Nucleotides as Monomers * Nucleotides are the monomers (building blocks) of DNA and RNA. 19. Three Parts of a Nucleotide Each nucleotide is made of: 1. Phosphate group (PO₄³⁻) 2. Five-carbon sugar * Deoxyribose (in DNA) * Ribose (in RNA) 3. Nitrogenous base * A, T, C, G (in DNA) * A, U, C, G (in RNA) 20. Nucleotides in DNA vs RNA Molecule Bases Used Sugar RNA Adenine (A), Uracil (U), Cytosine (C), Guanine (G) Ribose DNA Adenine (A), Thymine (T), Cytosine (C), Guanine (G) Deoxyribose 21. What Are Genes? * Genes are specific sequences of DNA that provide the instructions to make a particular protein. * Each gene codes for the amino acid sequence of a protein. 22. Complementary DNA Strands * DNA is double-stranded, with bases pairing complementarily: * A pairs with T (via 2 hydrogen bonds) * C pairs with G (via 3 hydrogen bonds) * The two strands run antiparallel (opposite directions) and complement each other in sequence and base pairing. 23. ATP: A Special Nucleotide * ATP (Adenosine Triphosphate) is an RNA "A" nucleotide (adenine + ribose) with two extra phosphate groups. * ATP is the cell's main energy currency: * When it loses a phosphate (becomes ADP), it releases energy used by the cell. LIPIDS: 24. What Are Lipids? * Lipids are hydrophobic or partially hydrophobic molecules. * They are nonpolar or mostly nonpolar, so they don’t dissolve well in water. * Made mostly of carbon (C), hydrogen (H), and some oxygen (O). 25. Three Main Types of Lipids 1. Triglycerides 2. Phospholipids 3. Steroids 26. Structure Comparison Lipid Type Basic Structure Triglycerides 1 glycerol + 3 fatty acids (linked by ester bonds) Phospholipids 1 glycerol, 2 fatty acids, 1 phosphate group (often with a polar head group) Steroids 4 fused carbon rings with various side chains (no fatty acids) Note: * Triglycerides are fully nonpolar (hydrophobic). * Phospholipids are amphipathic: have both hydrophobic tails and a hydrophilic head. * Steroids are largely nonpolar but can interact with membranes. 27. Functional Comparison Lipid Type Function Triglycerides Long-term energy storage, insulation, cushioning (found in adipose tissue) Phospholipids Main component of cell membranes (forms the lipid bilayer); regulates entry/exit of substances Cholesterol (a steroid) - Stabilizes cell membranes (in animals) Precursor for other steroids like: * Sex hormones (testosterone, estrogen) * Vitamin D * Cortisol (stress hormone) H. DNA, RNA, and Protein Synthesis 1. What Is DNA Replication? * DNA replication is the process of making an exact copy of the DNA. * It occurs in the nucleus of eukaryotic cells, during the S phase of the cell cycle. 2. How DNA Is Replicated Using Complementary Base Pairing * The DNA double helix unwinds, and each strand acts as a template for a new strand. * The bases on each strand pair according to the rules: * Adenine (A) pairs with Thymine (T) * Cytosine (C) pairs with Guanine (G) * As new nucleotides are added, they follow these base-pairing rules to create two identical DNA strands, each made up of one old strand and one newly synthesized strand. 3. Relationship Between Genes, DNA, and Chromosomes * DNA is the molecule that carries genetic information. * Genes are specific segments of DNA that provide the instructions to make proteins. * Chromosomes are long, coiled structures of DNA and protein that contain many genes. 4. Mutation * A mutation is a change in the DNA sequence. * Mutations can alter the structure of a protein and potentially change its function, which may lead to diseases or genetic disorders, but can also be harmless or beneficial. 5. Transcription and Translation * Transcription is the process of copying a gene's DNA sequence into mRNA. This happens in the nucleus. * Translation is the process where the mRNA sequence is read by ribosomes, and tRNA brings amino acids to form a protein. This takes place in the cytoplasm at the ribosome. 6. Processes of Transcription and Translation * Transcription involves the synthesis of mRNA from a DNA template. The mRNA then exits the nucleus and enters the cytoplasm. * Translation is the next step, where the ribosome reads the mRNA code and uses tRNA to bring amino acids. These amino acids are linked to form a protein. 7. Role of mRNA, tRNA, and rRNA in Translation * mRNA (messenger RNA) carries the genetic code from the DNA in the nucleus to the ribosome. * tRNA (transfer RNA) brings specific amino acids to the ribosome based on the codons in the mRNA. * rRNA (ribosomal RNA) is a structural part of the ribosome and helps assemble the amino acids into a protein. I. Structure and Function of Cells 1. The Three Tenets of Cell Theory * All living organisms are made of cells. * The cell is the basic unit of life (structure and function). * All cells arise from pre-existing cells. 2. Basic Structure of Eukaryotic Cells * Plasma Membrane: The outer boundary of the cell that controls the movement of substances in and out of the cell. It is composed of a phospholipid bilayer with embedded proteins. * Nucleus: The control center of the cell, containing the genetic material (DNA). It is surrounded by the nuclear envelope, which has pores to allow communication with the cytoplasm. * Cytoplasm: The gel-like substance inside the cell, between the plasma membrane and the nucleus. It contains the cytosol (liquid) and organelles (e.g., mitochondria, ribosomes). 3. Intracellular and Extracellular Fluids * Intracellular fluid (ICF): The fluid inside the cell, which makes up about two-thirds of the body’s total water. * Extracellular fluid (ECF): The fluid outside the cell, which includes interstitial fluid (fluid between cells), blood plasma, and lymph. * The relationship between ICF and ECF is that substances must pass through the plasma membrane (by various transport mechanisms) to move between these two compartments. 4. Structure and Function of the Cytoskeleton The cytoskeleton is a network of protein filaments and tubules that provide structural support to the cell. It helps maintain the cell's shape, assists in movement (both of the cell and within the cell), and plays a role in cell division. 5. Structure and Function of Ribosomes, RER, and Golgi Apparatus * Ribosomes: Small structures composed of RNA and proteins that are responsible for protein synthesis. They can be free-floating in the cytoplasm or attached to the rough endoplasmic reticulum (RER). * Rough Endoplasmic Reticulum (RER): A network of membranous tubules studded with ribosomes. The RER is involved in the synthesis and modification of proteins that are either secreted or incorporated into the cell membrane. * Golgi Apparatus: A stack of membrane-bound sacs that modifies, sorts, and packages proteins received from the RER for transport within the cell or secretion outside the cell. 6. How Ribosomes, RER, and Golgi Work Together in Protein Synthesis and Packaging * Ribosomes on the RER synthesize proteins. * These proteins are then transported into the lumen (inside) of the RER, where they may undergo modifications(e.g., folding, adding sugar chains). * The proteins are then sent to the Golgi apparatus, where they are further modified, sorted, and packaged into vesicles for transport to their destination (either outside the cell or to other parts of the cell). 7. Structure and Function of the Smooth Endoplasmic Reticulum (SER) * The smooth ER is a network of tubules without ribosomes. * It is involved in the synthesis of lipids, detoxification of drugs and poisons, and storage of calcium ions in muscle cells. 8. Structure and Function of Lysosomes * Lysosomes are membrane-bound organelles that contain digestive enzymes. * Their primary function is to break down waste materials, digest food particles, and destroy harmful bacteria or old cell parts (recycling). 9. Structure of Mitochondrion and Its Role in Energy Capture * The mitochondrion is a double-membraned organelle with an inner membrane that folds to form cristae(increasing surface area). * It is the powerhouse of the cell, where ATP (adenosine triphosphate), the cell’s energy currency, is produced through cellular respiration (a process that converts glucose and oxygen into energy). 10. Structure and Function of the Nucleus * The nucleus is surrounded by a double membrane called the nuclear envelope and contains chromatin (DNA and proteins). * It serves as the control center of the cell, housing the DNA and coordinating activities such as growth, metabolism, and protein synthesis by controlling gene expression. 11. Structure and Function of Cilia and Flagella * Cilia are short, hair-like projections that cover the surface of some cells. They move in a coordinated manner to move fluids or particles across the cell surface (e.g., in the respiratory tract to move mucus). * Flagella are long, whip-like structures that are used for cell movement (e.g., sperm cells). They work by rotating or beating in a propeller-like motion. J. The Plasma Membrane 1. Structure of the Plasma Membrane (Phospholipid Bilayer, Cholesterol, Proteins, and Carbohydrates) The plasma membrane is a selectively permeable barrier that separates the interior of the cell from the external environment. Its structure includes: * Phospholipid bilayer: This forms the basic structure of the membrane. The bilayer consists of hydrophilic heads(water-attracting) and hydrophobic tails (water-repelling), which arrange themselves to protect the hydrophobic tails from water and allow for membrane flexibility. * Cholesterol: Embedded within the phospholipid bilayer, cholesterol helps to maintain membrane fluidity, preventing it from becoming too rigid or too fluid at different temperatures. * Proteins: There are two main types of proteins in the plasma membrane: * Integral proteins: These span across the membrane and are involved in transport, acting as channels or carriers. * Peripheral proteins: These are attached to the surface of the membrane and are involved in signaling or maintaining the cell's shape. * Carbohydrates: These are attached to proteins (glycoproteins) or lipids (glycolipids) on the extracellular side of the membrane. They play a key role in cell recognition and communication. 2. Functions of the Plasma Membrane Components * Phospholipid Bilayer: Provides the basic structural framework of the membrane, serving as a barrier that separates the inside and outside of the cell. * Cholesterol: Stabilizes the membrane, keeping it fluid and flexible, and prevents the membrane from becoming too rigid at lower temperatures or too fluid at higher temperatures. * Proteins: * Transport proteins: Regulate the movement of substances across the membrane. * Receptor proteins: Detect signals from outside the cell and help in communication. * Anchor proteins: Attach the membrane to the cytoskeleton, providing structural support. * Carbohydrates: Play a key role in cell-cell recognition, immune responses, and adhesion. 3. Protein Receptors and Cell Communication Protein receptors on the plasma membrane allow cells to communicate with each other by binding to specific ligands(e.g., hormones, neurotransmitters). This binding triggers a signal transduction pathway inside the cell that can lead to various responses, such as gene expression or changes in cell behavior. 4. Factors Affecting Movement Across the Plasma Membrane The movement of molecules across the plasma membrane depends on: * Size: Small molecules (like gases, water) move more easily than large molecules (like proteins). * Electric charge: Charged molecules (ions) cannot easily pass through the hydrophobic interior of the membrane. They require transport proteins. * Lipid solubility: Nonpolar (lipid-soluble) molecules can pass through the membrane easily, while polar molecules require assistance from transport proteins. 5. Movement of Substances Across the Plasma Membrane Here’s a comparison of different mechanisms: * Simple Diffusion: Movement of molecules from high to low concentration, requiring no energy or assistance. (E.g., oxygen and carbon dioxide) * Osmosis: A form of diffusion specific to water. Water moves from an area of low solute concentration to high solute concentration through a semipermeable membrane. * Facilitated Diffusion: Movement of molecules from high to low concentration, but via transport proteins (e.g., glucose) because the molecules are too large or polar to move through the lipid bilayer directly. * Active Transport: Movement of molecules from low to high concentration, requiring energy (ATP) and transport proteins. This allows cells to accumulate substances even when they are in lower concentrations outside the cell (e.g., sodium-potassium pump). * Endocytosis: The process by which the cell engulfs large particles or liquids by folding the membrane around them and bringing them into the cell in a vesicle (requires energy). * Exocytosis: The reverse of endocytosis; it involves the expulsion of substances from the cell in a vesicle that fuses with the plasma membrane (requires energy). 6. Energy Needs of Each Process * Simple Diffusion: No energy required. * Osmosis: No energy required. * Facilitated Diffusion: No energy required (but requires a transport protein). * Active Transport: Requires energy (ATP). * Endocytosis: Requires energy. * Exocytosis: Requires energy. 7. Definitions: Isotonic, Hypotonic, and Hypertonic Solutions * Isotonic Solution: A solution where the concentration of solutes is the same inside and outside the cell. The cell maintains its normal shape. * Hypotonic Solution: A solution with a lower concentration of solutes compared to inside the cell. Water moves into the cell, causing it to swell. * Hypertonic Solution: A solution with a higher concentration of solutes compared to inside the cell. Water moves out of the cell, causing it to shrink. 8. Effects on Cell Volume in Different Solutions * Isotonic Solution: The cell’s volume stays the same because water moves in and out at the same rate. * Hypotonic Solution: The cell swells as water enters because there’s more water outside the cell than inside. * Hypertonic Solution: The cell shrinks as water leaves the cell to dilute the external environment. 9. Determining the Solution Type (Hypotonic, Hypertonic, Isotonic) You can determine the type of solution by comparing the concentration of solutes inside the cell to the concentration in the environment: * Hypotonic: More solutes inside the cell than in the environment. * Hypertonic: More solutes in the environment than inside the cell. * Isotonic: Equal solute concentrations inside and outside the cell. 10. Direction of Water Movement and Cell Shape * In hypotonic solutions, water moves into the cell, causing it to swell. * In hypertonic solutions, water moves out of the cell, causing it to shrink. * In isotonic solutions, water moves in and out at the same rate, so the cell stays the same shape. K. Energy and Cells 1. Role of ATP and ADP in Energy Transfer * ATP (Adenosine Triphosphate) is the primary energy currency of the cell. It consists of adenine (a nitrogenous base), ribose (a sugar), and three phosphate groups. ATP stores energy in the bonds between these phosphate groups. When ATP is hydrolyzed (a phosphate is removed), it releases energy, forming ADP (Adenosine Diphosphate) and an inorganic phosphate (Pi). * ADP is the product when ATP loses one phosphate group, and it can be "recharged" back into ATP by adding a phosphate group (through processes like cellular respiration). Thus, ATP and ADP cycle between energy storage and release. 2. Definitions of Key Terms * Cellular Respiration: A process that cells use to convert energy stored in food molecules (like glucose) into ATP. It includes glycolysis, the citric acid cycle, and oxidative phosphorylation (which includes the electron transport chain). * Glycolysis: The first step of cellular respiration that occurs in the cytoplasm, where glucose (6 carbons) is broken down into two molecules of pyruvate (3 carbons), producing a small amount of ATP and NADH. * Citric Acid Cycle (Krebs Cycle/Tricarboxylic Acid Cycle): Occurs in the mitochondrial matrix, where pyruvate is further broken down, releasing carbon dioxide and transferring electrons to carrier molecules like NADH and FADH₂, which will be used in the next step. * Oxidative Phosphorylation: The final stage of cellular respiration, which includes the electron transport chainand chemiosmosis. It occurs in the inner mitochondrial membrane and produces the majority of ATP. * Electron Transport Chain (ETC): A series of protein complexes in the inner mitochondrial membrane that transfer electrons from NADH and FADH₂ to oxygen, creating a proton gradient that powers ATP synthesis. 3. Energy Release from Food Molecules * During cellular respiration, energy stored in glucose and other food molecules is gradually released as the bonds in these molecules are broken. This energy is used to produce ATP, which cells use for various functions. 4. Location of Glycolysis * Glycolysis occurs in the cytoplasm of the cell. 5. Purpose of Glycolysis and Its Benefit * The purpose of glycolysis is to break down glucose into two molecules of pyruvate, which can be further processed in aerobic respiration (if oxygen is available). It also generates a small amount of ATP and NADH for the cell, providing an energy source. * Benefit: It provides energy for cells in the absence of oxygen (anaerobic conditions) and sets the stage for the citric acid cycle and oxidative phosphorylation when oxygen is present. 6. Reactants and Products of Glycolysis * Reactants: 1 molecule of glucose (6 carbon atoms), 2 NAD⁺, 2 ATP, 4 ADP, and 4 inorganic phosphate (Pi). * Products: 2 molecules of pyruvate (3 carbon atoms), 2 NADH, 4 ATP (net gain of 2 ATP), and 2 water molecules. 7. Location of the Citric Acid Cycle * The citric acid cycle occurs in the mitochondrial matrix. 8. Products of the Citric Acid Cycle * For each glucose molecule (which is broken into 2 pyruvate molecules), the citric acid cycle generates: * 2 ATP (via substrate-level phosphorylation) * 6 NADH * 2 FADH₂ * 4 CO₂ (as waste) 9. Location of Oxidative Phosphorylation and the Electron Transport Chain * Oxidative phosphorylation occurs in the inner mitochondrial membrane, specifically across the electron transport chain (ETC) and the ATP synthase enzyme complex. 10. Products of Oxidative Phosphorylation * Products: * Up to 34 ATP (through ATP synthase via chemiosmosis) * Water (as oxygen combines with protons and electrons) 11. Role of Oxygen in Oxidative Phosphorylation * Oxygen acts as the final electron acceptor in the electron transport chain. It combines with electrons and protons to form water. This step is crucial because it prevents the buildup of electrons in the electron transport chain, allowing the chain to continue functioning. 12. Comparison of ATP Production in Glycolysis, Citric Acid Cycle, and Oxidative Phosphorylation * Glycolysis: Produces a net gain of 2 ATP (directly) and 2 NADH. * Citric Acid Cycle: Produces 2 ATP (directly), 6 NADH, and 2 FADH₂. * Oxidative Phosphorylation: Produces the majority of ATP, up to 34 ATP (through electron transport and chemiosmosis). 13. Lactic Acid Fermentation and the Lack of Oxygen * When oxygen is unavailable, cells can undergo lactic acid fermentation (in animals) or alcoholic fermentation(in yeast). This process allows for the regeneration of NAD⁺ by converting pyruvate into lactic acid (in animals), enabling glycolysis to continue producing ATP without oxygen. However, it produces much less ATP than aerobic respiration. [Note: You do NOT need to know the intermediate steps of glycolysis, the citric acid cycle, or oxidative phosphorylation. L. Mitosis and Meiosis 1. Definition of Mitosis * Mitosis is the process of cell division where a parent cell divides to form two genetically identical daughter cells. Mitosis is essential for growth, tissue repair, and asexual reproduction in organisms. 2. Outcome of Mitosis * After mitosis, two daughter cells are produced, each with the same number of chromosomes as the parent cell. * Example: If a parent cell has 46 chromosomes, each of the two daughter cells will also have 46 chromosomes. 3. When Mitosis and Meiosis Occur * Mitosis occurs during processes like growth, cellular repair, and asexual reproduction (for example, in skin cells or the growth of multicellular organisms). * Meiosis, on the other hand, occurs only in gamete production (sperm and eggs) in order to reduce the chromosome number by half, ensuring the proper chromosome number in offspring. 4. Function of Mitosis * The primary function of mitosis is to generate genetically identical cells for purposes such as growth, tissue repair, and asexual reproduction. * Cell division is a broader term that refers to the process of a single cell dividing into two, which could refer to mitosis or meiosis, depending on the context. 5. Definition of Meiosis * Meiosis is a type of cell division that reduces the chromosome number by half to form four non-identical daughter cells, which are gametes (sperm or eggs). It is essential for sexual reproduction. 6. Definition of Crossing Over and Independent Assortment * Crossing Over: During meiosis, homologous chromosomes exchange segments of their genetic material. This leads to new combinations of alleles, increasing genetic diversity in offspring. * Independent Assortment: The process by which different genes independently separate from one another during meiosis. This ensures that each gamete contains a mix of alleles from the parent. 7. Contribution of Crossing Over and Independent Assortment to Genetic Variation * Crossing over and independent assortment both contribute to genetic variation by ensuring that the gametes (sperm and eggs) produced during meiosis contain different combinations of genetic material. This variation is important for evolution and adaptation in populations. 8. Outcome of Meiosis * Meiosis results in four daughter cells, each with half the number of chromosomes of the parent cell (haploid). * For example, if the parent cell has 46 chromosomes, each of the four daughter cells will have 23 chromosomes. * This ensures that when two gametes (sperm and egg) unite during fertilization, the resulting zygote will have the correct number of chromosomes. 9. Definition of Gametes and the Necessity of Meiosis * Gametes are reproductive cells (sperm and egg) that have half the number of chromosomes as regular body cells (haploid). Meiosis is necessary for gamete production because it reduces the chromosome number by half, ensuring that when two gametes fuse during fertilization, the resulting zygote has the correct diploid number of chromosomes. M. Body Systems 1. Circulatory System * Function: The circulatory system is responsible for transporting blood, nutrients, gases (like oxygen and carbon dioxide), hormones, and waste products throughout the body. It includes the heart, blood vessels, and blood. The circulatory system helps maintain homeostasis by regulating temperature, pH, and fluid balance. 2. Digestive System * Function: The digestive system is responsible for breaking down food into smaller molecules (such as sugars, amino acids, and fatty acids) that can be absorbed into the bloodstream. It includes the mouth, esophagus, stomach, small intestine, large intestine, liver, pancreas, and gallbladder. It helps with the absorption of nutrients and the elimination of waste. 3. Nervous System * Function: The nervous system controls and coordinates body activities by transmitting electrical signals between different parts of the body. It includes the brain, spinal cord, and nerves. The nervous system helps regulate and respond to internal and external stimuli, maintaining homeostasis and enabling voluntary and involuntary actions. 4. Endocrine System * Function: The endocrine system regulates bodily functions by releasing hormones from glands (like the pituitary, thyroid, adrenal glands, and pancreas) into the bloodstream. These hormones control processes such as metabolism, growth, reproduction, and mood. It works with the nervous system to regulate long-term processes in the body. 5. Reproductive System * Function: The reproductive system is responsible for producing offspring. In males, it includes the testes, penis, vas deferens, and other structures involved in sperm production and delivery. In females, it includes the ovaries, fallopian tubes, uterus, and vagina, which are involved in egg production, fertilization, and the development of offspring during pregnancy. 6. Integumentary System * Function: The integumentary system includes the skin, hair, nails, and sweat glands. It protects the body from physical damage, pathogens, and dehydration. It also helps regulate body temperature and enables sensory perception (touch, pain, temperature). Additionally, it synthesizes vitamin D. 7. Skeletal System * Function: The skeletal system provides structural support for the body, protects vital organs (like the brain and heart), and facilitates movement by serving as points of attachment for muscles. It also stores minerals (such as calcium and phosphorus) and produces blood cells in the bone marrow. The skeleton is made up of bones, cartilage, ligaments, and tendons. 8. Respiratory System * Function: The respiratory system is responsible for the exchange of gases (oxygen and carbon dioxide) between the body and the environment. It includes the lungs, trachea, bronchi, bronchioles, and alveoli. Oxygen is inhaled into the lungs, and carbon dioxide is exhaled as a waste product. It also helps regulate the body's pH balance by controlling the levels of CO₂ in the blood. 9. Muscular System * Function: The muscular system allows movement of the body and its parts. It includes skeletal muscles, smooth muscles, and cardiac muscles. Skeletal muscles are responsible for voluntary movements, while smooth muscles control involuntary actions (like digestion and blood vessel constriction). Cardiac muscles control the contractions of the heart. Muscles also help maintain posture and generate heat. 10. Urinary System * Function: The urinary system, also known as the excretory system, is responsible for removing waste products from the body and regulating fluid and electrolyte balance. It includes the kidneys, ureters, bladder, and urethra. The kidneys filter the blood, producing urine that contains waste and excess substances, which are then excreted from the body. 11. Immune System * Function: The immune system protects the body from harmful pathogens (such as bacteria, viruses, and fungi) and foreign substances. It includes white blood cells, lymph nodes, spleen, bone marrow, and thymus. The immune system detects and neutralizes threats through processes like inflammation, phagocytosis, and the production of antibodies. It also plays a role in identifying and destroying cancerous cells. N. Reading Skills 1. Read a short science article that relates in some fashion to the objectives above. 2. After reading the article, answer a series of questions concerning the information covered in the article.

Homeostasis is the process by which a living organism maintains a stable internal environment despite changes in external conditions. (Alternate definition: keeping the inside of the body balanced and stable, even when things outside change.)

Organisms use feedback mechanisms to help keep their internal environment stable (homeostasis). There are two main types: negative feedback and positive feedback.
1. Negative feedback – This is the most common way the body maintains balance. When something in the body changes too much, negative feedback works to bring it back to normal.
   * Example: If your body gets too hot, you start to sweat to cool down.
2. Positive feedback – This type of feedback increases a change instead of stopping it. It pushes the body further in the same direction, but only for a short time, usually to complete a process.
   * Example: During childbirth, hormones keep increasing to help the muscles contract until the baby is born.

B. The Metric System
State the basic units of the metric system for length, mass, time and volume.
Length – Meter (m)
Mass – Gram (g)
Time – Second (s)
Volume – Liter (L)

Identify the fraction or multiple associated with each of the following prefixes: kilo,
deci, centi, milli, micro, and nano.
* Kilo (k) = 1,000 (10³)
* Deci (d) = 1/10 (0.1 or 10⁻¹)
* Centi (c) = 1/100 (0.01 or 10⁻²)
* Milli (m) = 1/1,000 (0.001 or 10⁻³)
* Micro (µ) = 1/1,000,000 (0.000001 or 10⁻⁶)
* Nano (n) = 1/1,000,000,000 (0.000000001 or 10⁻⁹)
Combine the prefixes above with a metric unit and know the correct abbreviation
of the combined prefix and unit.

Convert quantities between the metric units.

Steps to Convert Between Units:
1. Find the starting and target units.
2. Count the number of steps between them on the metric scale.
3. Move the decimal point that many places—to the right if converting to a smaller unit, to the left if converting to a larger unit.

C. Atoms, Molecules, Bonds and Properties of Matter
1. Define the term element.
An element is a pure substance made of only one type of atom.
2. Common chemical symbols:
Oxygen – O
Carbon – C
Hydrogen – H
Nitrogen – N
Calcium – Ca
Potassium – K
Sodium – Na
Chlorine – Cl
Iron – Fe
Phosphorus – P
3. Chemical Formulas
* Carbon dioxide – CO₂
* Carbon monoxide – CO
* Water – H₂O
* Hydrochloric acid – HCl
* Sodium chloride – NaCl
* Glucose – C₆H₁₂O₆
* Sodium bicarbonate (sodium hydrogen carbonate) – NaHCO₃
4. Define: Atom
An atom is the smallest unit of an element that retains the properties of that element. It consists of a nucleus (with protons and neutrons) and electrons that orbit the nucleus.
5. Basic Structure of an Atom
* Protons – Positively charged particles found in the nucleus
* Neutrons – Neutral particles (no charge) found in the nucleus
* Electrons – Negatively charged particles that orbit the nucleus in electron shells
6. Charge & Location
* Protons – Positive (+), in the nucleus
* Neutrons – Neutral (0), in the nucleus
* Electrons – Negative (−), in electron clouds/orbitals around the nucleus
7. Define: Isotope
An isotope is an atom of the same element (same number of protons) but with a different number of neutrons, resulting in a different atomic mass.
8. Isotopes in Medicine
Isotopes are used in medical diagnosis and treatment, such as:
* Radioactive iodine (I-131) for treating thyroid disorders
* Technetium-99m for imaging organs
* Carbon-14 for tracing metabolic pathways
9. Define: Molecule and Ion
* Molecule – A group of atoms bonded together (e.g., H₂O, CO₂)
* Ion – An atom or molecule with a net electrical charge due to loss or gain of electrons (e.g., Na⁺, Cl⁻)
Electrons play a critical role in chemical bonding by being shared (in covalent bonds) or transferred (in ionic bonds).
10. Covalent vs. Ionic Bonds
* Covalent bond: Atoms share electrons (e.g., H₂O, CO₂)
* Ionic bond: Atoms transfer electrons, forming ions (e.g., NaCl)
Diagrams:
* Covalent: Lines between atoms (e.g., H–O–H)
* Ionic: Often shown using charges (Na⁺ Cl⁻)
11. Bond Strength
* Covalent bonds are generally stronger and require more energy to break.
* Ionic bonds are also strong, especially in solid form, but can dissociate more easily in water.
12. Polar vs. Nonpolar Bonds
* Polar bonds: Unequal sharing of electrons; one atom is more electronegative (e.g., H₂O)
* Nonpolar bonds: Equal sharing of electrons (e.g., O₂, CH₄)
Polar molecules: Have partial charges and interact with water
Nonpolar molecules: Do not have partial charges and are generally hydrophobic
13. Type of Bond by Molecule
* Carbon dioxide (CO₂) – Nonpolar covalent
* Water (H₂O) – Polar covalent
* Hydrochloric acid (HCl) – Polar covalent
* Sodium chloride (NaCl) – Ionic
* Oxygen gas (O₂) – Nonpolar covalent
* Sodium bicarbonate (NaHCO₃) – Ionic (Na⁺ with bicarbonate ion), and covalent within HCO₃⁻
14. Hydrogen Bond
A hydrogen bond is a weak attraction between a hydrogen atom (already covalently bonded to a more electronegative atom like oxygen or nitrogen) and another electronegative atom.
Characteristics:
* Weak individually, but strong in large numbers
* Essential in water properties and DNA structure
15. Hydrogen Bonds in Diagrams
Hydrogen bonds are typically shown as dotted or dashed lines (e.g., H···O) between molecules.
16. Define: Matter and Mass
* Matter: Anything that has mass and takes up space
* Mass: The amount of matter in an object; not dependent on gravity
17. States of Matter
* Solid – Definite shape and volume
* Liquid – Definite volume, takes shape of container
* Gas – No definite shape or volume, expands to fill space
18. Particle Motion by State
* Solid – Tightly packed, vibrate in place
* Liquid – Loosely packed, move past each other
* Gas – Widely spaced, move freely and rapidly
Temperature increases motion in all states.
19. Temperature, Pressure, and Volume (Closed System)
* As temperature increases, particles move faster, increasing pressure (if volume is constant).
* Increasing volume can lower pressure, and vice versa (if temperature is constant).
* These relationships are described by gas laws (Boyle’s, Charles’, etc.).

D. Water
1. Describe the Polarity of Water
Water (H₂O) is a polar molecule because:
* The oxygen atom is more electronegative than hydrogen, pulling shared electrons closer to itself.
* This creates a partial negative charge (δ⁻) on oxygen and partial positive charges (δ⁺) on the hydrogens.
* The molecule has a bent shape, not linear, which creates a dipole (a positive and negative end).
This polarity allows water molecules to form hydrogen bonds with each other and with other polar molecules.

3. Biological Importance of Hydrogen Bonds
* Between Water Molecules:
   * Create cohesion and surface tension
   * Give water its high boiling point and heat capacity
   * Essential for water transport in plants (cohesion + adhesion = capillary action)
* Between Other Polar Covalent Molecules:
   * Stabilize the structures of proteins (e.g., α-helices and β-sheets)
   * Hold together strands of DNA (between nitrogenous bases: A–T, G–C)
   * Influence the 3D shape of enzymes and other biological molecules
Hydrogen bonds are weak individually but strong collectively, making them ideal for temporary but crucial interactions in biological systems.

This distinction is critical in cell membrane formation, where hydrophobic tails face inward and hydrophilic heads face outward in the phospholipid bilayer.

E. Acids, Bases, pH, and Buffers
1. Definitions: Acid, Base, and Hydrogen Ion (Proton)
* Acid: A substance that donates hydrogen ions (H⁺) (protons) in solution.
* Base: A substance that accepts hydrogen ions (H⁺) or releases hydroxide ions (OH⁻) in solution.
* Hydrogen ion (H⁺): A proton—a hydrogen atom that has lost its only electron, often simply written as H⁺.

3. Reading the pH Scale
* 0–6: Acidic (e.g., lemon juice ~pH 2)
* 7: Neutral (e.g., pure water)
* 8–14: Basic (e.g., bleach ~pH 13)
Every 1-unit change in pH = 10x change in H⁺ concentration.

5. Define: Buffer
A buffer is a chemical system that resists changes in pH when small amounts of acid or base are added.
6. How Buffers Maintain Homeostasis
* Buffers work by absorbing H⁺ or OH⁻ ions to keep the pH stable.
* Example: The bicarbonate buffer system in blood:
HCO₃⁻ + H⁺ ⇌ H₂CO₃ ⇌ CO₂ + H₂OHCO₃⁻ + H⁺ ⇌ H₂CO₃ ⇌ CO₂ + H₂O
* Helps maintain blood pH around 7.35–7.45, which is crucial for proper cell function and enzyme activity.
7. Define: Dissociation
Dissociation is the process where a molecule breaks apart into ions when dissolved in water.
8. Effect of Dissociation: Producing Anions and Cations
   * When compounds dissociate, they form:
   * Cations: Positively charged ions (e.g., Na⁺, H⁺)
   * Anions: Negatively charged ions (e.g., Cl⁻, OH⁻)
Example:
NaCl → Na⁺ + Cl⁻
9. Dissociation and Acid/Base Strength
   * Strong acids/bases: Completely dissociate in water (e.g., HCl, NaOH) → more ions → stronger effect on pH
   * Weak acids/bases: Partially dissociate (e.g., acetic acid, NH₃) → fewer ions → weaker effect on pH
10. Characteristics of a Neutralization Reaction
A neutralization reaction occurs when an acid and a base react to form:
   * Water (H₂O) and
   * A salt (ionic compound)
General formula:
Acid (H⁺) + Base (OH⁻) → H₂O + SaltAcid (H⁺) + Base (OH⁻) → H₂O + Salt
Example:
HCl + NaOH → H₂O + NaCl
F. Chemical Reactions

2. Examples of Kinetic and Potential Energy
   * Kinetic Energy:
   * Muscle movement
   * Flowing blood
   * A moving car
   * Potential Energy:
   * Chemical bonds in glucose
   * Water held behind a dam
   * A compressed spring
3. Energy in Chemical Reactions (Organisms)
   * Organisms use chemical reactions to:
   * Break down compounds (e.g., glucose) → release energy (catabolic reactions)
   * Build new compounds (e.g., proteins, DNA) → require energy (anabolic reactions)
   * Cellular respiration breaks glucose to release ATP
   * Photosynthesis stores energy in glucose
4. Simple Chemical Reaction Example (Proper Notation)
Example (cellular respiration simplified):
C6H12O6+6O2→6CO2+6H2O+ATPC6H12O6+6O2→6CO2+6H2O+ATP
(Reactants on the left, products on the right; arrow shows direction of reaction)

6. Chemical Equilibrium
In a reversible reaction at equilibrium:
   * The rate of the forward reaction equals the rate of the reverse reaction
   * Concentrations of reactants and products stay constant, but reactions still occur
7. Definitions
   * Catalyst: Substance that speeds up a reaction without being consumed
   * Enzyme: A biological catalyst, usually a protein
   * Substrate: The specific reactant that an enzyme acts on
   * Products: The resulting molecules after the reaction
   * Activation Energy: The energy required to start a reaction
   * Active Site: The region of the enzyme where the substrate binds
8. Enzyme Characteristics
   * Specificity: Each enzyme works on one specific substrate (lock-and-key model)
   * Reusability: Enzymes are not used up or permanently changed in the reaction
   * Speed: They lower activation energy to speed up reactions
   * Conditions: Work best under specific pH and temperature; can be denatured if conditions are wrong
9. How Enzymes Work (Including Activation Energy and Reaction Rate)
   * Enzymes are biological catalysts—they speed up chemical reactions without being used up.
   * They work by lowering the activation energy needed for a reaction to begin.
   * Activation energy is the energy barrier that must be overcome for reactants to be converted into products.
   * The enzyme has an active site where the substrate binds, forming an enzyme-substrate complex.
   * Once the reaction occurs, the products are released, and the enzyme is free to be reused.
🔽 Effect of Enzymes:
   * Lower activation energy
   * Increase reaction rate
   * Do not alter the final products or equilibrium
10. Factors Affecting Enzyme Activity
🧪 pH:
   * Each enzyme has an optimal pH (e.g., pepsin in the stomach works best at pH 2).
   * If the pH is too high or too low, the enzyme’s shape (and active site) can be altered or denatured, reducing or stopping activity.
🌡️ Temperature:
   * Enzyme activity increases with temperature, up to an optimal point.
   * If the temperature gets too high, enzymes can denature, losing their shape and function.
   * If it's too cold, reactions slow down because molecules move more slowly and collide less often.
G. Biomolecules
1. Why Carbon Is a Versatile Element
Carbon is central to all biomolecules because of its unique bonding properties:
   * Has 4 valence electrons, allowing it to form 4 covalent bonds with other atoms.
   * Can form single, double, or triple bonds.
   * Can bond with many elements (e.g., H, O, N, P, S) and other carbon atoms, forming:
   * Chains, rings, and branches
   * This makes carbon the backbone of carbohydrates, lipids, proteins, and nucleic acids.

3. Define Monomer and Polymer
   * Monomer: A single subunit or building block (e.g., glucose, amino acid).
   * Polymer: A large molecule made of repeating monomers bonded together.
Polymer
	Monomers
	Carbohydrates
	                 Monosaccharides
	Proteins
	                 Amino acids
	Nucleic acids
	                 Nucleotides
	Lipids (some, like triglycerides)
	 Glycerol + fatty acids (not true polymers)
	4. Reactions: Making and Breaking Polymers
Reaction Type
	What It Does
	Description
	Dehydration synthesis (Condensation)
	Builds polymers
	Monomers bond together by removing a water molecule. Requires energy.
	Hydrolysis
	Breaks polymers
	Water is added to break bonds between monomers. Releases energy.
	Example:
   * Dehydration:
Glucose+Glucose→Maltose+H2OGlucose+Glucose→Maltose+H2O
   * Hydrolysis:
Maltose+H2O→Glucose+GlucoseMaltose+H2O→Glucose+Glucose
CARBOHYDRATES: 
5. Carbohydrate Terms and Structure
      * Monosaccharide:
      * The simplest carbohydrates; one sugar unit
      * Monomer of all larger carbohydrates
      * Example: Glucose
      * Disaccharide:
      * Made of two monosaccharides joined by dehydration synthesis
      * Example: Sucrose = Glucose + Fructose
      * Polysaccharide:
      * A polymer of many monosaccharides (hundreds to thousands)
      * Can be branched or unbranched
      * Example: Starch

7. Functions of Each Carbohydrate

PROTEINS:
8. Amino Acids and Proteins
      * Amino acids are the monomers (building blocks) of proteins.
      * They link together by peptide bonds to form polypeptides (chains), which fold into proteins.
9. Parts of an Amino Acid
Every amino acid has the same basic structure:
      * Central carbon atom (C)
      * Amino group (—NH₂)
      * Carboxyl group (—COOH)
      * Hydrogen atom (H)
      * R group (side chain that varies in each amino acid)
📌 The R group is what makes each of the 20 amino acids unique.
10. Role of the R Group
      * The R group determines:
      * Polarity (polar or nonpolar)
      * Charge (positive, negative, or neutral)
      * Hydrophobic or hydrophilic nature
      * Special structures (e.g., disulfide bonds from —SH in cysteine)
      * The R group influences how the protein folds and functions.
11. Four Levels of Protein Structure
Level
	Description
	Bond Types
	Primary
	Sequence of amino acids
	Covalent peptide bonds
	Secondary
	Local folding into α-helices or β-pleated sheets
	Hydrogen bonds
	Tertiary
	3D shape of the entire polypeptide
	Hydrogen, disulfide, ionic, and hydrophobic interactions
	Quaternary
	Combination of 2+ polypeptide chains
	Same as tertiary (non-covalent + covalent)
	12. Importance of Shape to Protein Function
      * A protein’s shape (structure) determines its function.
      * If the shape is altered, the protein may lose its ability to bind to other molecules (e.g., enzymes, receptors, antibodies).
13. Definition of Denaturation
      * Denaturation is the unfolding or distortion of a protein’s 3D shape.
      * This process disrupts bonds (especially hydrogen bonds), but does not break the amino acid sequence.
14. Effect of Denaturation on Function
      * Denatured proteins lose their specific shape, and therefore can’t function properly.
      * Example: A denatured enzyme can’t bind to its substrate.
15. Effects of pH and Temperature on Protein Function
      * pH: Extremes can alter charges on amino acids and disrupt hydrogen/ionic bonds, leading to denaturation.
      * Temperature: High temps can cause increased molecular motion, breaking bonds and denaturing the protein.
      * Low temps slow function but don’t denature.
16. Examples of Protein Functions in Cells
Function
	Example
	Enzymes
	Lactase, amylase (catalysts)
	Transport
	Hemoglobin (O₂ transport), membrane channels
	Structure
	Collagen (skin, connective tissue), keratin
	Defense
	Antibodies (immune system)
	Signaling
	Hormones like insulin
	Movement
	Actin, myosin (muscle contraction)
	NUCLEIC ACIDS:
17. Two Major Nucleic Acids in Cells
      * DNA (Deoxyribonucleic acid)
      * RNA (Ribonucleic acid)
18. Nucleotides as Monomers
      * Nucleotides are the monomers (building blocks) of DNA and RNA.
19. Three Parts of a Nucleotide
Each nucleotide is made of:
      1. Phosphate group (PO₄³⁻)
      2. Five-carbon sugar
      * Deoxyribose (in DNA)
      * Ribose (in RNA)
      3. Nitrogenous base
      * A, T, C, G (in DNA)
      * A, U, C, G (in RNA)
20. Nucleotides in DNA vs RNA
Molecule
	Bases Used
	Sugar
	RNA
	Adenine (A), Uracil (U), Cytosine (C), Guanine (G)
	Ribose
	DNA
	Adenine (A), Thymine (T), Cytosine (C), Guanine (G)
	Deoxyribose

21. What Are Genes?
      * Genes are specific sequences of DNA that provide the instructions to make a particular protein.
      * Each gene codes for the amino acid sequence of a protein.
22. Complementary DNA Strands
      * DNA is double-stranded, with bases pairing complementarily:
      * A pairs with T (via 2 hydrogen bonds)
      * C pairs with G (via 3 hydrogen bonds)
      * The two strands run antiparallel (opposite directions) and complement each other in sequence and base pairing.
23. ATP: A Special Nucleotide
      * ATP (Adenosine Triphosphate) is an RNA "A" nucleotide (adenine + ribose) with two extra phosphate groups.
      * ATP is the cell's main energy currency:
      * When it loses a phosphate (becomes ADP), it releases energy used by the cell.
LIPIDS:
24. What Are Lipids?
      * Lipids are hydrophobic or partially hydrophobic molecules.
      * They are nonpolar or mostly nonpolar, so they don’t dissolve well in water.
      * Made mostly of carbon (C), hydrogen (H), and some oxygen (O).
25. Three Main Types of Lipids
      1. Triglycerides
      2. Phospholipids
      3. Steroids
26. Structure Comparison
Lipid Type
	Basic Structure
	Triglycerides
	1 glycerol + 3 fatty acids (linked by ester bonds)
	Phospholipids
	1 glycerol, 2 fatty acids, 1 phosphate group (often with a polar head group)
	Steroids
	4 fused carbon rings with various side chains (no fatty acids)
	Note:
      * Triglycerides are fully nonpolar (hydrophobic).
      * Phospholipids are amphipathic: have both hydrophobic tails and a hydrophilic head.
      * Steroids are largely nonpolar but can interact with membranes.
27. Functional Comparison
Lipid Type
	Function
	Triglycerides
	Long-term energy storage, insulation, cushioning (found in adipose tissue)
	Phospholipids
	Main component of cell membranes (forms the lipid bilayer); regulates entry/exit of substances
	Cholesterol (a steroid)
	- Stabilizes cell membranes (in animals)
	Precursor for other steroids like:
      * Sex hormones (testosterone, estrogen)
      * Vitamin D
      * Cortisol (stress hormone)
H. DNA, RNA, and Protein Synthesis
1. What Is DNA Replication?
      * DNA replication is the process of making an exact copy of the DNA.
      * It occurs in the nucleus of eukaryotic cells, during the S phase of the cell cycle.
2. How DNA Is Replicated Using Complementary Base Pairing
      * The DNA double helix unwinds, and each strand acts as a template for a new strand.
      * The bases on each strand pair according to the rules:
      * Adenine (A) pairs with Thymine (T)
      * Cytosine (C) pairs with Guanine (G)
      * As new nucleotides are added, they follow these base-pairing rules to create two identical DNA strands, each made up of one old strand and one newly synthesized strand.
3. Relationship Between Genes, DNA, and Chromosomes
      * DNA is the molecule that carries genetic information.
      * Genes are specific segments of DNA that provide the instructions to make proteins.
      * Chromosomes are long, coiled structures of DNA and protein that contain many genes.
4. Mutation
      * A mutation is a change in the DNA sequence.
      * Mutations can alter the structure of a protein and potentially change its function, which may lead to diseases or genetic disorders, but can also be harmless or beneficial.
5. Transcription and Translation
      * Transcription is the process of copying a gene's DNA sequence into mRNA. This happens in the nucleus.
      * Translation is the process where the mRNA sequence is read by ribosomes, and tRNA brings amino acids to form a protein. This takes place in the cytoplasm at the ribosome.
6. Processes of Transcription and Translation
      * Transcription involves the synthesis of mRNA from a DNA template. The mRNA then exits the nucleus and enters the cytoplasm.
      * Translation is the next step, where the ribosome reads the mRNA code and uses tRNA to bring amino acids. These amino acids are linked to form a protein.
7. Role of mRNA, tRNA, and rRNA in Translation
      * mRNA (messenger RNA) carries the genetic code from the DNA in the nucleus to the ribosome.
      * tRNA (transfer RNA) brings specific amino acids to the ribosome based on the codons in the mRNA.
      * rRNA (ribosomal RNA) is a structural part of the ribosome and helps assemble the amino acids into a protein.
I. Structure and Function of Cells
1. The Three Tenets of Cell Theory
      * All living organisms are made of cells.
      * The cell is the basic unit of life (structure and function).
      * All cells arise from pre-existing cells.
2. Basic Structure of Eukaryotic Cells
      * Plasma Membrane: The outer boundary of the cell that controls the movement of substances in and out of the cell. It is composed of a phospholipid bilayer with embedded proteins.
      * Nucleus: The control center of the cell, containing the genetic material (DNA). It is surrounded by the nuclear envelope, which has pores to allow communication with the cytoplasm.
      * Cytoplasm: The gel-like substance inside the cell, between the plasma membrane and the nucleus. It contains the cytosol (liquid) and organelles (e.g., mitochondria, ribosomes).
3. Intracellular and Extracellular Fluids
      * Intracellular fluid (ICF): The fluid inside the cell, which makes up about two-thirds of the body’s total water.
      * Extracellular fluid (ECF): The fluid outside the cell, which includes interstitial fluid (fluid between cells), blood plasma, and lymph.
      * The relationship between ICF and ECF is that substances must pass through the plasma membrane (by various transport mechanisms) to move between these two compartments.
4. Structure and Function of the Cytoskeleton
The cytoskeleton is a network of protein filaments and tubules that provide structural support to the cell. It helps maintain the cell's shape, assists in movement (both of the cell and within the cell), and plays a role in cell division.
5. Structure and Function of Ribosomes, RER, and Golgi Apparatus
      * Ribosomes: Small structures composed of RNA and proteins that are responsible for protein synthesis. They can be free-floating in the cytoplasm or attached to the rough endoplasmic reticulum (RER).
      * Rough Endoplasmic Reticulum (RER): A network of membranous tubules studded with ribosomes. The RER is involved in the synthesis and modification of proteins that are either secreted or incorporated into the cell membrane.
      * Golgi Apparatus: A stack of membrane-bound sacs that modifies, sorts, and packages proteins received from the RER for transport within the cell or secretion outside the cell.
6. How Ribosomes, RER, and Golgi Work Together in Protein Synthesis and Packaging
      * Ribosomes on the RER synthesize proteins.
      * These proteins are then transported into the lumen (inside) of the RER, where they may undergo modifications(e.g., folding, adding sugar chains).
      * The proteins are then sent to the Golgi apparatus, where they are further modified, sorted, and packaged into vesicles for transport to their destination (either outside the cell or to other parts of the cell).
7. Structure and Function of the Smooth Endoplasmic Reticulum (SER)
      * The smooth ER is a network of tubules without ribosomes.
      * It is involved in the synthesis of lipids, detoxification of drugs and poisons, and storage of calcium ions in muscle cells.
8. Structure and Function of Lysosomes
      * Lysosomes are membrane-bound organelles that contain digestive enzymes.
      * Their primary function is to break down waste materials, digest food particles, and destroy harmful bacteria or old cell parts (recycling).
9. Structure of Mitochondrion and Its Role in Energy Capture
      * The mitochondrion is a double-membraned organelle with an inner membrane that folds to form cristae(increasing surface area).
      * It is the powerhouse of the cell, where ATP (adenosine triphosphate), the cell’s energy currency, is produced through cellular respiration (a process that converts glucose and oxygen into energy).
10. Structure and Function of the Nucleus
      * The nucleus is surrounded by a double membrane called the nuclear envelope and contains chromatin (DNA and proteins).
      * It serves as the control center of the cell, housing the DNA and coordinating activities such as growth, metabolism, and protein synthesis by controlling gene expression.
11. Structure and Function of Cilia and Flagella
      * Cilia are short, hair-like projections that cover the surface of some cells. They move in a coordinated manner to move fluids or particles across the cell surface (e.g., in the respiratory tract to move mucus).
      * Flagella are long, whip-like structures that are used for cell movement (e.g., sperm cells). They work by rotating or beating in a propeller-like motion.
J. The Plasma Membrane
1. Structure of the Plasma Membrane (Phospholipid Bilayer, Cholesterol, Proteins, and Carbohydrates)
The plasma membrane is a selectively permeable barrier that separates the interior of the cell from the external environment. Its structure includes:
      * Phospholipid bilayer: This forms the basic structure of the membrane. The bilayer consists of hydrophilic heads(water-attracting) and hydrophobic tails (water-repelling), which arrange themselves to protect the hydrophobic tails from water and allow for membrane flexibility.
      * Cholesterol: Embedded within the phospholipid bilayer, cholesterol helps to maintain membrane fluidity, preventing it from becoming too rigid or too fluid at different temperatures.
      * Proteins: There are two main types of proteins in the plasma membrane:
      * Integral proteins: These span across the membrane and are involved in transport, acting as channels or carriers.
      * Peripheral proteins: These are attached to the surface of the membrane and are involved in signaling or maintaining the cell's shape.
      * Carbohydrates: These are attached to proteins (glycoproteins) or lipids (glycolipids) on the extracellular side of the membrane. They play a key role in cell recognition and communication.
2. Functions of the Plasma Membrane Components
      * Phospholipid Bilayer: Provides the basic structural framework of the membrane, serving as a barrier that separates the inside and outside of the cell.
      * Cholesterol: Stabilizes the membrane, keeping it fluid and flexible, and prevents the membrane from becoming too rigid at lower temperatures or too fluid at higher temperatures.
      * Proteins:
      * Transport proteins: Regulate the movement of substances across the membrane.
      * Receptor proteins: Detect signals from outside the cell and help in communication.
      * Anchor proteins: Attach the membrane to the cytoskeleton, providing structural support.
      * Carbohydrates: Play a key role in cell-cell recognition, immune responses, and adhesion.
3. Protein Receptors and Cell Communication
Protein receptors on the plasma membrane allow cells to communicate with each other by binding to specific ligands(e.g., hormones, neurotransmitters). This binding triggers a signal transduction pathway inside the cell that can lead to various responses, such as gene expression or changes in cell behavior.
4. Factors Affecting Movement Across the Plasma Membrane
The movement of molecules across the plasma membrane depends on:
      * Size: Small molecules (like gases, water) move more easily than large molecules (like proteins).
      * Electric charge: Charged molecules (ions) cannot easily pass through the hydrophobic interior of the membrane. They require transport proteins.
      * Lipid solubility: Nonpolar (lipid-soluble) molecules can pass through the membrane easily, while polar molecules require assistance from transport proteins.
5. Movement of Substances Across the Plasma Membrane
Here’s a comparison of different mechanisms:
      * Simple Diffusion: Movement of molecules from high to low concentration, requiring no energy or assistance. (E.g., oxygen and carbon dioxide)
      * Osmosis: A form of diffusion specific to water. Water moves from an area of low solute concentration to high solute concentration through a semipermeable membrane.
      * Facilitated Diffusion: Movement of molecules from high to low concentration, but via transport proteins (e.g., glucose) because the molecules are too large or polar to move through the lipid bilayer directly.
      * Active Transport: Movement of molecules from low to high concentration, requiring energy (ATP) and transport proteins. This allows cells to accumulate substances even when they are in lower concentrations outside the cell (e.g., sodium-potassium pump).
      * Endocytosis: The process by which the cell engulfs large particles or liquids by folding the membrane around them and bringing them into the cell in a vesicle (requires energy).
      * Exocytosis: The reverse of endocytosis; it involves the expulsion of substances from the cell in a vesicle that fuses with the plasma membrane (requires energy).
6. Energy Needs of Each Process
      * Simple Diffusion: No energy required.
      * Osmosis: No energy required.
      * Facilitated Diffusion: No energy required (but requires a transport protein).
      * Active Transport: Requires energy (ATP).
      * Endocytosis: Requires energy.
      * Exocytosis: Requires energy.
7. Definitions: Isotonic, Hypotonic, and Hypertonic Solutions
      * Isotonic Solution: A solution where the concentration of solutes is the same inside and outside the cell. The cell maintains its normal shape.
      * Hypotonic Solution: A solution with a lower concentration of solutes compared to inside the cell. Water moves into the cell, causing it to swell.
      * Hypertonic Solution: A solution with a higher concentration of solutes compared to inside the cell. Water moves out of the cell, causing it to shrink.
8. Effects on Cell Volume in Different Solutions
      * Isotonic Solution: The cell’s volume stays the same because water moves in and out at the same rate.
      * Hypotonic Solution: The cell swells as water enters because there’s more water outside the cell than inside.
      * Hypertonic Solution: The cell shrinks as water leaves the cell to dilute the external environment.
9. Determining the Solution Type (Hypotonic, Hypertonic, Isotonic)
You can determine the type of solution by comparing the concentration of solutes inside the cell to the concentration in the environment:
      * Hypotonic: More solutes inside the cell than in the environment.
      * Hypertonic: More solutes in the environment than inside the cell.
      * Isotonic: Equal solute concentrations inside and outside the cell.
10. Direction of Water Movement and Cell Shape
      * In hypotonic solutions, water moves into the cell, causing it to swell.
      * In hypertonic solutions, water moves out of the cell, causing it to shrink.
      * In isotonic solutions, water moves in and out at the same rate, so the cell stays the same shape.

K. Energy and Cells
1. Role of ATP and ADP in Energy Transfer
      * ATP (Adenosine Triphosphate) is the primary energy currency of the cell. It consists of adenine (a nitrogenous base), ribose (a sugar), and three phosphate groups. ATP stores energy in the bonds between these phosphate groups. When ATP is hydrolyzed (a phosphate is removed), it releases energy, forming ADP (Adenosine Diphosphate) and an inorganic phosphate (Pi).
      * ADP is the product when ATP loses one phosphate group, and it can be "recharged" back into ATP by adding a phosphate group (through processes like cellular respiration). Thus, ATP and ADP cycle between energy storage and release.
2. Definitions of Key Terms
      * Cellular Respiration: A process that cells use to convert energy stored in food molecules (like glucose) into ATP. It includes glycolysis, the citric acid cycle, and oxidative phosphorylation (which includes the electron transport chain).
      * Glycolysis: The first step of cellular respiration that occurs in the cytoplasm, where glucose (6 carbons) is broken down into two molecules of pyruvate (3 carbons), producing a small amount of ATP and NADH.
      * Citric Acid Cycle (Krebs Cycle/Tricarboxylic Acid Cycle): Occurs in the mitochondrial matrix, where pyruvate is further broken down, releasing carbon dioxide and transferring electrons to carrier molecules like NADH and FADH₂, which will be used in the next step.
      * Oxidative Phosphorylation: The final stage of cellular respiration, which includes the electron transport chainand chemiosmosis. It occurs in the inner mitochondrial membrane and produces the majority of ATP.
      * Electron Transport Chain (ETC): A series of protein complexes in the inner mitochondrial membrane that transfer electrons from NADH and FADH₂ to oxygen, creating a proton gradient that powers ATP synthesis.
3. Energy Release from Food Molecules
      * During cellular respiration, energy stored in glucose and other food molecules is gradually released as the bonds in these molecules are broken. This energy is used to produce ATP, which cells use for various functions.
4. Location of Glycolysis
      * Glycolysis occurs in the cytoplasm of the cell.
5. Purpose of Glycolysis and Its Benefit
      * The purpose of glycolysis is to break down glucose into two molecules of pyruvate, which can be further processed in aerobic respiration (if oxygen is available). It also generates a small amount of ATP and NADH for the cell, providing an energy source.
      * Benefit: It provides energy for cells in the absence of oxygen (anaerobic conditions) and sets the stage for the citric acid cycle and oxidative phosphorylation when oxygen is present.
6. Reactants and Products of Glycolysis
      * Reactants: 1 molecule of glucose (6 carbon atoms), 2 NAD⁺, 2 ATP, 4 ADP, and 4 inorganic phosphate (Pi).
      * Products: 2 molecules of pyruvate (3 carbon atoms), 2 NADH, 4 ATP (net gain of 2 ATP), and 2 water molecules.
7. Location of the Citric Acid Cycle
      * The citric acid cycle occurs in the mitochondrial matrix.
8. Products of the Citric Acid Cycle
      * For each glucose molecule (which is broken into 2 pyruvate molecules), the citric acid cycle generates:
      * 2 ATP (via substrate-level phosphorylation)
      * 6 NADH
      * 2 FADH₂
      * 4 CO₂ (as waste)
9. Location of Oxidative Phosphorylation and the Electron Transport Chain
      * Oxidative phosphorylation occurs in the inner mitochondrial membrane, specifically across the electron transport chain (ETC) and the ATP synthase enzyme complex.
10. Products of Oxidative Phosphorylation
      * Products:
      * Up to 34 ATP (through ATP synthase via chemiosmosis)
      * Water (as oxygen combines with protons and electrons)
11. Role of Oxygen in Oxidative Phosphorylation
      * Oxygen acts as the final electron acceptor in the electron transport chain. It combines with electrons and protons to form water. This step is crucial because it prevents the buildup of electrons in the electron transport chain, allowing the chain to continue functioning.
12. Comparison of ATP Production in Glycolysis, Citric Acid Cycle, and Oxidative Phosphorylation
      * Glycolysis: Produces a net gain of 2 ATP (directly) and 2 NADH.
      * Citric Acid Cycle: Produces 2 ATP (directly), 6 NADH, and 2 FADH₂.
      * Oxidative Phosphorylation: Produces the majority of ATP, up to 34 ATP (through electron transport and chemiosmosis).
13. Lactic Acid Fermentation and the Lack of Oxygen
      * When oxygen is unavailable, cells can undergo lactic acid fermentation (in animals) or alcoholic fermentation(in yeast). This process allows for the regeneration of NAD⁺ by converting pyruvate into lactic acid (in animals), enabling glycolysis to continue producing ATP without oxygen. However, it produces much less ATP than aerobic respiration.
[Note: You do NOT need to know the intermediate steps of glycolysis, the
citric acid cycle, or oxidative phosphorylation.

L. Mitosis and Meiosis
1. Definition of Mitosis
      * Mitosis is the process of cell division where a parent cell divides to form two genetically identical daughter cells. Mitosis is essential for growth, tissue repair, and asexual reproduction in organisms.
2. Outcome of Mitosis
      * After mitosis, two daughter cells are produced, each with the same number of chromosomes as the parent cell.
      * Example: If a parent cell has 46 chromosomes, each of the two daughter cells will also have 46 chromosomes.
3. When Mitosis and Meiosis Occur
      * Mitosis occurs during processes like growth, cellular repair, and asexual reproduction (for example, in skin cells or the growth of multicellular organisms).
      * Meiosis, on the other hand, occurs only in gamete production (sperm and eggs) in order to reduce the chromosome number by half, ensuring the proper chromosome number in offspring.
4. Function of Mitosis
      * The primary function of mitosis is to generate genetically identical cells for purposes such as growth, tissue repair, and asexual reproduction.
      * Cell division is a broader term that refers to the process of a single cell dividing into two, which could refer to mitosis or meiosis, depending on the context.
5. Definition of Meiosis
      * Meiosis is a type of cell division that reduces the chromosome number by half to form four non-identical daughter cells, which are gametes (sperm or eggs). It is essential for sexual reproduction.
6. Definition of Crossing Over and Independent Assortment
      * Crossing Over: During meiosis, homologous chromosomes exchange segments of their genetic material. This leads to new combinations of alleles, increasing genetic diversity in offspring.
      * Independent Assortment: The process by which different genes independently separate from one another during meiosis. This ensures that each gamete contains a mix of alleles from the parent.
7. Contribution of Crossing Over and Independent Assortment to Genetic Variation
      * Crossing over and independent assortment both contribute to genetic variation by ensuring that the gametes (sperm and eggs) produced during meiosis contain different combinations of genetic material. This variation is important for evolution and adaptation in populations.
8. Outcome of Meiosis
      * Meiosis results in four daughter cells, each with half the number of chromosomes of the parent cell (haploid).
      * For example, if the parent cell has 46 chromosomes, each of the four daughter cells will have 23 chromosomes.
      * This ensures that when two gametes (sperm and egg) unite during fertilization, the resulting zygote will have the correct number of chromosomes.
9. Definition of Gametes and the Necessity of Meiosis
      * Gametes are reproductive cells (sperm and egg) that have half the number of chromosomes as regular body cells (haploid). Meiosis is necessary for gamete production because it reduces the chromosome number by half, ensuring that when two gametes fuse during fertilization, the resulting zygote has the correct diploid number of chromosomes.
M. Body Systems
1. Circulatory System
      * Function: The circulatory system is responsible for transporting blood, nutrients, gases (like oxygen and carbon dioxide), hormones, and waste products throughout the body. It includes the heart, blood vessels, and blood. The circulatory system helps maintain homeostasis by regulating temperature, pH, and fluid balance.
2. Digestive System
      * Function: The digestive system is responsible for breaking down food into smaller molecules (such as sugars, amino acids, and fatty acids) that can be absorbed into the bloodstream. It includes the mouth, esophagus, stomach, small intestine, large intestine, liver, pancreas, and gallbladder. It helps with the absorption of nutrients and the elimination of waste.
3. Nervous System
      * Function: The nervous system controls and coordinates body activities by transmitting electrical signals between different parts of the body. It includes the brain, spinal cord, and nerves. The nervous system helps regulate and respond to internal and external stimuli, maintaining homeostasis and enabling voluntary and involuntary actions.
4. Endocrine System
      * Function: The endocrine system regulates bodily functions by releasing hormones from glands (like the pituitary, thyroid, adrenal glands, and pancreas) into the bloodstream. These hormones control processes such as metabolism, growth, reproduction, and mood. It works with the nervous system to regulate long-term processes in the body.
5. Reproductive System
      * Function: The reproductive system is responsible for producing offspring. In males, it includes the testes, penis, vas deferens, and other structures involved in sperm production and delivery. In females, it includes the ovaries, fallopian tubes, uterus, and vagina, which are involved in egg production, fertilization, and the development of offspring during pregnancy.
6. Integumentary System
      * Function: The integumentary system includes the skin, hair, nails, and sweat glands. It protects the body from physical damage, pathogens, and dehydration. It also helps regulate body temperature and enables sensory perception (touch, pain, temperature). Additionally, it synthesizes vitamin D.
7. Skeletal System
      * Function: The skeletal system provides structural support for the body, protects vital organs (like the brain and heart), and facilitates movement by serving as points of attachment for muscles. It also stores minerals (such as calcium and phosphorus) and produces blood cells in the bone marrow. The skeleton is made up of bones, cartilage, ligaments, and tendons.
8. Respiratory System
      * Function: The respiratory system is responsible for the exchange of gases (oxygen and carbon dioxide) between the body and the environment. It includes the lungs, trachea, bronchi, bronchioles, and alveoli. Oxygen is inhaled into the lungs, and carbon dioxide is exhaled as a waste product. It also helps regulate the body's pH balance by controlling the levels of CO₂ in the blood.
9. Muscular System
      * Function: The muscular system allows movement of the body and its parts. It includes skeletal muscles, smooth muscles, and cardiac muscles. Skeletal muscles are responsible for voluntary movements, while smooth muscles control involuntary actions (like digestion and blood vessel constriction). Cardiac muscles control the contractions of the heart. Muscles also help maintain posture and generate heat.
10. Urinary System
      * Function: The urinary system, also known as the excretory system, is responsible for removing waste products from the body and regulating fluid and electrolyte balance. It includes the kidneys, ureters, bladder, and urethra. The kidneys filter the blood, producing urine that contains waste and excess substances, which are then excreted from the body.
11. Immune System
      * Function: The immune system protects the body from harmful pathogens (such as bacteria, viruses, and fungi) and foreign substances. It includes white blood cells, lymph nodes, spleen, bone marrow, and thymus. The immune system detects and neutralizes threats through processes like inflammation, phagocytosis, and the production of antibodies. It also plays a role in identifying and destroying cancerous cells.
N. Reading Skills
1. Read a short science article that relates in some fashion to the objectives above.
2. After reading the article, answer a series of questions concerning the
information covered in the article.

Transcript for:Overview of Multicellular Organism Biology

Transcript for:
Overview of Multicellular Organism Biology