Lecture Notes: Multicellular Organisms and Basic Biological Concepts

A. Levels of Organization

• Atoms: Basic units of matter (e.g., carbon, hydrogen, oxygen)
• Molecules: Atoms bonded (e.g., water, proteins, DNA)
• Organelles: Structures in cells made of molecules (e.g., mitochondria)
• Cells: Basic units of life; different types for different functions (e.g., muscle cells)
• Tissues: Groups of similar cells performing a function (e.g., muscle tissue)
• Organs: Composed of tissues working together (e.g., heart)
• Organ Systems: Groups of organs (e.g., digestive system)
• Organism: Complete living being

Homeostasis and Feedback Mechanisms

• Homeostasis: Maintaining a stable internal environment
• Negative Feedback: Restores balance (e.g., sweating to cool down)
• Positive Feedback: Increases change temporarily (e.g., childbirth)

B. Metric System

• Basic units:
  • Length: Meter (m)
  • Mass: Gram (g)
  • Time: Second (s)
  • Volume: Liter (L)
• Prefixes:
  • Kilo = 1,000
  • Deci = 1/10
  • Centi = 1/100
  • Milli = 1/1,000
  • Micro = 1/1,000,000
  • Nano = 1/1,000,000,000
• Conversion Steps: Identify units, count steps, move decimal

C. Atoms, Molecules, Bonds, and Matter

1. Element: Pure substance of one type of atom
2. Common Symbols: O, C, H, N, Ca, K, Na, Cl, Fe, P
3. Chemical Formulas:

• CO₂, H₂O, NaCl

4. Atom Structure:

• Protons: Positive, nucleus
  • Neutrons: Neutral, nucleus
  • Electrons: Negative, orbits

5. Isotope: Same protons, different neutrons
6. Isotopes in Medicine: E.g., I-131 for thyroid
7. Molecule vs. Ion:

• Molecule: Atoms bonded
  • Ion: Charged atom/molecule

8. Covalent vs. Ionic Bonds:

• Covalent: Shared electrons
  • Ionic: Transferred electrons

9. Bond Strength:

• Covalent > Ionic

10. Polar vs. Nonpolar:

• Polar: Unequal sharing (e.g., water)
  • Nonpolar: Equal sharing

11. Hydrogen Bond: Weak attraction, important in water & DNA
12. Matter: Anything with mass and space
13. States of Matter: Solid, liquid, gas
14. Particle Motion: Increases with temperature
15. Temperature, Pressure, Volume: Relationship described by gas laws

D. Water

1. Polarity of Water: Polar molecule with partial charges
2. Hydrogen Bonds: Between water contributes to high boiling point
3. Biological Importance: Cohesion, protein structure, DNA stability

E. Acids, Bases, pH, and Buffers

1. Acid: Donates H⁺ ions
2. Base: Accepts H⁺ or releases OH⁻
3. pH Scale:

• 0-6: Acidic
  • 7: Neutral
  • 8-14: Basic

4. Buffer: Resists pH changes
5. Dissociation: Molecule forms ions in water
6. Neutralization Reaction: Acid + Base → Water + Salt

F. Chemical Reactions

1. Kinetic vs. Potential Energy
2. Energy in Reactions: Release or require energy
3. Chemical Equilibrium: Forward and reverse reaction rates equal
4. Enzymes: Catalysts, specificity, work by lowering activation energy
5. Factors Affecting Enzyme Activity: pH, temperature

G. Biomolecules

1. Carbon: Versatile bonding properties
2. Monomer vs. Polymer
3. Carbohydrates: Monosaccharides, Disaccharides, Polysaccharides
4. Proteins:

• Amino Acids: Building blocks, peptide bonds
  • Protein Structure: Primary to Quaternary

5. Nucleic Acids: DNA and RNA, nucleotide structure
6. ATP: Energy currency
7. Lipids: Hydrophobic molecules, types include triglycerides

H. DNA, RNA, and Protein Synthesis

1. DNA Replication: Making an exact copy
2. Transcription & Translation: Transcribe DNA to mRNA, translate mRNA to protein
3. mRNA, tRNA, rRNA: Roles in protein synthesis

I. Structure and Function of Cells

1. Cell Theory: All living things are cells
2. Cell Structures: Plasma membrane, nucleus, cytoplasm
3. Organelles: Ribosomes, ER, Golgi apparatus

J. Plasma Membrane

1. Structure: Phospholipid bilayer, proteins, cholesterol
2. Functions: Transport, signaling

K. Energy and Cells

1. ATP & ADP: Energy transfer
2. Cellular Respiration: Glycolysis, Citric Acid Cycle, Oxidative Phosphorylation

L. Mitosis and Meiosis

1. Mitosis: Cell division for growth
2. Meiosis: Gamete production, genetic variation

M. Body Systems

1. Circulatory System: Transports blood and nutrients
2. Digestive System: Breaks down food
3. Nervous System: Controls body activities
4. Endocrine System: Regulates via hormones
5. Reproductive System: Produces offspring
6. Integumentary System: Protects body, regulates temperature
7. Skeletal System: Supports body, stores minerals
8. Respiratory System: Gas exchange
9. Muscular System: Allows movement
10. Urinary System: Removes waste
11. Immune System: Protects against pathogens