Protein Structure Overview

Overview

This lecture explains the basic structure of proteins, the formation of peptide bonds, and details the four levels of protein structure.

Protein Basics

Proteins are polymers made of many amino acids linked together.
Each amino acid is a monomer; a chain of amino acids is a polypeptide.
Amino acids are connected by peptide bonds.

Amino Acid Structure

An amino acid has a central chiral carbon bonded to a hydrogen, an amine group (NH₂), an R group (side chain), and a carboxyl group (COOH).
The N-terminal is the end with the amine group; the C-terminal is the end with the carboxyl group.

Peptide Bond Formation

Two amino acids join in a condensation (dehydration) reaction, releasing water and forming a peptide bond (amide bond).
The peptide bond forms between the carbon of one amino acid’s carboxyl group and the nitrogen of another’s amine group.
A chain of two amino acids is a dipeptide.

Levels of Protein Structure

Primary Structure: the specific amino acid sequence of a protein.
Secondary Structure: localized shapes like alpha helix (spiral, stabilized by hydrogen bonds) and beta pleated sheet (sheet-like structure, also stabilized by hydrogen bonds).
Tertiary Structure: the overall three-dimensional folding of a single polypeptide chain.
Quaternary Structure: combination of multiple polypeptide subunits into one functional protein (e.g., hemoglobin has four subunits).

Key Terms & Definitions

Protein — a polymer of amino acids.
Amino Acid — the basic monomer unit of proteins, with a central chiral carbon, amine group, carboxyl group, and R group.
Peptide Bond — covalent bond formed between two amino acids via a condensation reaction.
Primary Structure — the sequence of amino acids in a protein.
Secondary Structure — alpha helix and beta pleated sheet formations stabilized by hydrogen bonds.
Tertiary Structure — complete 3D folding of a single protein subunit.
Quaternary Structure — assembly of multiple protein subunits.

Action Items / Next Steps

Review diagrams of amino acid structure and protein folding.
Memorize the four levels of protein structure and their characteristics.Energy and the Living Cell
- Chemotroph: Organisms that obtain energy by oxidizing chemical compounds (e.g., animals, many bacteria).
- Phototroph: Organisms that use light as their primary energy source (e.g., plants, algae).
- Heterotroph: Organisms that consume other organisms for energy (e.g., animals, fungi).
- Autotroph: Organisms that make their own food from inorganic substances (e.g., plants via photosynthesis).
- Cellular respiration: The process of breaking down glucose to produce ATP. Occurs in three stages: glycolysis, Krebs cycle, and ETC.
- Photosynthesis: The process by which autotrophs convert light energy into chemical energy (glucose).
- Phosphorylation: Addition of a phosphate group to a molecule (often to ADP to form ATP).
- Dephosphorylation: Removal of a phosphate group from a molecule (often from ATP to release energy).
- Entropy: A measure of disorder; increases as energy is transformed.
- 2nd Law of Thermodynamics: Energy transformations increase entropy; not all energy is usable (some lost as heat).
- Aerobic respiration: Cellular respiration with oxygen; more efficient, producing ~36 ATP per glucose.
- Anaerobic respiration: Cellular respiration without oxygen; less efficient, produces ~2 ATP.
🔬 Glycolysis
- Location: Cytoplasm
- Oxygen needed?: No
- Starting reactant: Glucose
- End products: 2 pyruvate, 2 ATP (net), 2 NADH
- Gross ATP: 4 ATP
- Net ATP: 2 ATP
- NADH produced: 2
- ATP production type: Substrate-level phosphorylation
- First half = Energy investment phase: Uses 2 ATP to phosphorylate intermediates
 - First molecule: Glucose
 - Last molecule: Fructose 1,6-bisphosphate
- Enzyme between fructose 6-P and fructose 1,6-bisP: Phosphofructokinase (PFK)ATP regulation: Allosteric inhibition of PFK by high ATP levels
- Isomerase: Enzyme that rearranges molecules (e.g., glucose-6-P to fructose-6-P)
- Second phase = Energy payoff phase
 - Start: G3P (glyceraldehyde-3-phosphate)
 - End: Pyruvate
- Fermentation:
 - In yeast: Ethanol + CO₂
 - In bacteria: Lactic acid or ethanol (varies)
 - In animals: Lactic acid
 - Lifesaving: Allows ATP production without O₂; regenerates NAD⁺
🔁 Transition Reactions & Krebs Cycle (Citric Acid Cycle)
- Aerobic respiration?: Yes
- Transition reaction location: Mitochondrial matrix
- O₂ required?: Indirectly (needed for ETC to function)
- Transition reaction: Pyruvate (3C) → Acetyl-CoA (2C) + CO₂ + NADH
- Acetyl-CoA: Joins with oxaloacetate (4C) → citric acid (6C)
- Isocitric acid: Formed from citric acid (rearranged)
- GTP: Similar to ATP; made in Krebs cycle; often used in protein synthesis
- Why not use GTP directly?: Converted to ATP or used in specific pathways
- Krebs cycle summary (per glucose):
 - 2 ATP (substrate-level)
 - 6 NADH
 - 2 FADH₂
 - 4 CO₂
- Enzyme complex: Multiple enzymes working together (e.g., pyruvate dehydrogenase)
- Why CoA is the key: It delivers acetyl groups to start the cycle
- Mitochondria structure:
 - Matrix: Krebs cycle, transition reaction
 - Inner membrane: ETC
 - Cristae: Folds that increase surface area
⚡ Electron Transport Chain (ETC) & ATP Production
- ETC location: Inner mitochondrial membrane
- Key structures:
 - Outer membrane
 - Intermembrane spaceMatrix
 - Embedded proteins: NADH dehydrogenase, cytochromes, ATP synthase
 - Cytochromes: Electron carriers in ETC
 - Electronegativity: Drives electron movement toward O₂
 - Proton pumps: Pump H⁺ into intermembrane space
 - ATP production: Chemiosmosis via ATP synthase
 - Final electron acceptor: Oxygen → water
 - Overall glucose equation:
 C6H12O6+6O2→6CO2+6H2O+ 36ATPC6H12O6+6O2→6CO2+6H2O+ 36ATP
 - Cyanide/CO poisoning: Inhibits cytochrome a3 → ETC stops → no ATP → cell death
 - Waste energy: Released as heat
 - Net ATP from glucose: ~36 ATP (2 glycolysis, 2 Krebs, 32 ETC)
 🌱 Photosynthesis
 - Autotroph vs Heterotroph: Same as above
 - Chlorophyll a/b: Light-absorbing pigments (a = primary)
 - Accessory pigments: Help absorb additional wavelengths
 - Antenna complex: Group of pigments that pass excitation energy to reaction center
 - Excitation energy: Energy absorbed by pigments from light
 - Photosystem I (PSI): Uses P700; produces NADPH
 - Photosystem II (PSII): Uses P680; splits water, starts ETC
 - Light reactions: In thylakoid membranes, produce ATP & NADPH
 - Dark reactions (Calvin Cycle): In stroma, fix carbon into glucose
 - ETC: In chloroplasts too, connects PSII to PSI
 - Ferredoxin: Final electron carrier in PSI
 - Structures:
 - Chloroplast: Site of photosynthesis
 - Stroma: Fluid inside chloroplast
 - Thylakoid: Disc-like membrane
 - Grana: Stacks of thylakoids
 - Cyclic phosphorylation: Only PSI used; only ATP made
 - Non-cyclic phosphorylation: PSII + PSI; ATP and NADPH made
 - Calvin Cycle Phases:
 - Carbon fixation: CO₂ + RuBP → 3-PGA
 - Reduction: 3-PGA → G3P using ATP & NADPH
 - Regeneration: RuBP regenerated
 - Reducing power: NADPH from light reactions
 - ATP synthase: Uses proton gradient to make ATP
 - Protein Z: Helps move electrons in PSII
 - Proton gradient: Drives ATP synthesis
 - Photocenter: Where energy is transferred in PSNADPH: Electron carrier for Calvin Cycle
 - RuBP: 5-carbon sugar in Calvin Cycle
 - RuBisCO: Enzyme that fixes CO₂
 - C3 vs C4 plants:
 - C3: Normal photosynthesis; vulnerable to photorespiration
 - C4: Special separation of fixation to reduce losses
 - Photorespiration: O₂ used instead of CO₂ → wasteful
 - Plant use of glucose: Energy, cellulose, starch, lipids
 Key Terms and Concepts
 
 Atoms and Bonds
 - Atom: Smallest unit of matter.
 - Element: A pure substance made of only one kind of atom (e.g., H, O, C).
 - Atomic number: Number of protons in the nucleus.
 - Atomic mass: Protons + neutrons.
 - Neutron / Proton / Electron: Subatomic particles (0 / +1 / -1 charge).
 - Ion: Charged atom (lost or gained electrons).
 - Isomer: Molecules with same formula, different structure.
 - Covalent bond: Electrons shared (e.g., H₂O).
 - Ionic bond: Electrons transferred (e.g., NaCl).
 - Polar covalent bond: Unequal sharing of electrons (e.g., H₂O).
 - Hydrogen bond: Weak attraction between polar molecules.
 Acids, Bases, pH
 - pH: Scale of hydrogen ion concentration (0 = acid, 14 = base).
 - Buffer: Resists pH changes.
 - Acid: Releases H⁺ ions (low pH).
 - Base: Accepts H⁺ or releases OH⁻ (high pH).
 - Neutralization: Acid + base → water + salt
 🍔 Macromolecules (Know structures and functions)
 
 Carbohydrates
 - Monosaccharide: Simple sugar (glucose).
 - Disaccharide: Two sugars (sucrose).
 - Polysaccharide: Many sugars (starch, cellulose).
 - Function: Quick energy, structure in plants (cellulose).Lipids
 - Fatty acid + Glycerol → Lipid
 - Saturated fat: No double bonds (solid).
 - Unsaturated fat: One or more double bonds (liquid).
 - Hydrophobic: Repels water.
 - Function: Long-term energy, insulation, membranes.
 Proteins
 - Monomer: Amino acid
 - Polypeptide: Chain of amino acids
 - Peptide bond: Links amino acids
 - Structure levels:
 - Primary: Sequence
 - Secondary: α-helix or β-pleated sheet
 - Tertiary: 3D shape
 - Quaternary: Multiple chains
 - Functions: Enzymes, structure, transport
 Nucleic Acids
 - Monomer: Nucleotide (sugar + phosphate + base)
 - Types: DNA & RNA
 - Function: Store and transfer genetic info
 🔄 Reactions & Enzymes
 - Dehydration synthesis: Builds molecules by removing water.
 - Hydrolysis: Breaks molecules by adding water.
 - Redox reaction: Transfer of electrons.
 - Oxidized: Loses electrons
 - Reduced: Gains electrons
 - Catalysis: Speeding up a reaction
 - Enzyme: Protein catalyst that lowers activation energy
 - Activation energy: Energy needed to start a reaction
 - Active site: Where substrate binds on enzyme
 - Inhibitors:
 - Competitive: Blocks active site
 - Non-competitive: Changes enzyme shape
 - End product / allosteric inhibition: Product inhibits pathway
 - Denatured enzyme: No longer functional (due to pH/temp)Draw and Know:
 - General amino acid:
 
 Central carbon (C)
 
 Amino group (NH₂)
 
 Carboxyl group (COOH)
 
 R-group (varies)
 - Peptide bond forms between carboxyl and amino group.
 ⚡ Energy and Thermodynamics
 - Entropy: Measure of disorder
 - 1st Law: Energy can't be created/destroyed
 - 2nd Law: Energy transformations increase entropy
 - Endothermic: Absorbs energy (positive ΔG, graph goes up)
 - Exothermic: Releases energy (negative ΔG, graph goes down)
 - ΔG: Gibbs free energy change (negative = spontaneous)
 - Free energy: Energy available to do work
 🧪 Functional Groups (Be able to recognize and name):
 - Hydroxyl (-OH)
 - Carboxyl (-COOH)
 - Amino (-NH₂)
 - Phosphate (-PO₄)
 - Carbonyl (C=O)
 🧫 Cell Membranes and Transport
 - Cell membrane: Phospholipid bilayer + proteins
 
 Phospholipids: Hydrophilic heads, hydrophobic tails
 
 Proteins: Channels, pumps, receptors
 
 Cholesterol: Stabilizes membrane
 - Polarity & Solubility:
 
 Polar = soluble in water
 
 Non-polar = not soluble
 - Transport:Passive transport: No energy
 
 Diffusion: High → low
 
 Facilitated diffusion: Uses protein channels
 
 Osmosis: Water diffusion
 - Active transport: Requires ATP
 
 Sodium-potassium pump: Moves ions against gradient
 
 Coupled transport: One molecule moves with gradient to help another go against it
 - Permeability:
 
 Permeable: Anything passes
 
 Semi-permeable: Selective
 
 Impermeable: Nothing passes
 - Aquaporins: Protein channels for water
 🔁 Metabolism
 - Metabolism = Catabolism + Anabolism
 
 Anabolism: Builds molecules (requires energy)
 
 Catabolism: Breaks molecules (releases energy)
 - ATP: Energy currency of cell
 - Phosphorylation: Adding phosphate to ADP → ATP
 - Dephosphorylation: ATP → ADP + Pi
 - Exothermic reactions: Release energy
 - Endothermic reactions: Absorb energy
 - Biochemical pathway: Series of enzyme-controlled reactions
 
 More efficient than isolated chemical reactions
 💡 Examples & Applications
 - Top 5 elements in humans: C, H, O, N, P
 - Coenzymes: Organic helper molecules (e.g., NAD⁺, FAD)
 - Cofactors: Inorganic enzyme helpers (e.g., metal ions)
 - Lock and key model: Enzyme = lock, substrate = key
 - Specificity: Each enzyme fits only one substrate
 People to Know
 - Watson & Crick: Built the first accurate 3D model of the DNA double helix based on Rosalind Franklin’s X-ray crystallography data.Chargaff: Discovered base pairing rules (A = T, G = C).
 - Mendel: Father of genetics; studied inheritance in pea plants.
 - Rosalind Franklin: Took X-ray diffraction images of DNA (notably Photo 51), critical to discovering DNA’s helical structure.
 - Griffith (transformation experiment): Discovered that harmless bacteria could be "transformed" by genetic material from dead pathogenic bacteria.
 - Hershey & Chase: Confirmed DNA (not protein) is the genetic material using radioactive labeling of bacteriophages.
 🧪 DNA & RNA Structure
 - Ribose: Sugar in RNA (has one more oxygen than deoxyribose).
 - Deoxyribose: Sugar in DNA (missing an oxygen).
 - Purines: Adenine (A) and Guanine (G) — double-ring structures.
 - Pyrimidines: Cytosine (C), Thymine (T), Uracil (U) — single-ring.
 - Nucleotides: Building blocks of DNA/RNA (sugar + phosphate + base).
 - Nitrogenous bases:
 
 DNA: A, T, G, C
 
 RNA: A, U, G, C
 - 5’ and 3’ ends: Refer to carbon positions on the sugar — directionality of DNA/RNA strands.
 - Hydrogen bonds: Hold base pairs together (A-T = 2 bonds, G-C = 3 bonds).
 - Double helix: Two antiparallel strands of DNA twisted like a ladder.
 - Chromosome: Tightly coiled DNA + protein (histones).
 - Chromatin: Loosely packed DNA in the nucleus.
 - Plasmid: Small circular DNA found in bacteria.
 🔬 Prokaryotes vs Eukaryotes
 
 Feature
 
 Prokaryotes
 
 Eukaryotes
 
 Nucleus
 
 No
 
 Yes
 
 DNA
 
 Circular (plasmids)
 
 Linear chromosomes
 
 Organelles
 
 No membrane-bound organelles
 
 Membrane-bound organelles
 
 Example
 
 Bacteria
 
 Plants, animals, fungi, protists
 
 📚 DNA vs RNA
 
 Feature
 
 DNA
 
 RNA
 
 Sugar
 
 Deoxyribose
 
 Ribose
 
 Bases
 
 A, T, G, C
 
 A, U, G, C
 
 Strands
 
 Double
 
 Single
 
 Location
 
 Nucleus
 
 Nucleus, cytoplasm
 
 Function
 
 Stores genetic information
 
 Transfers info, builds proteins
 
 🧬 DNA Replication
 - Semi-conservative: Each new DNA molecule has one old and one new strand.
 - Initiation: Helicase unzips DNA at origin of replication.
 - Elongation:
 
 Leading strand: Synthesized continuously (5'→3').
 
 Lagging strand: Made in fragments (Okazaki fragments).
 
 RNA primase: Adds RNA primers to start synthesis.
 
 DNA polymerase: Adds new DNA nucleotides.
 
 DNA ligase: Seals gaps between fragments.
 
 Gyrase: Relieves supercoiling ahead of the replication fork.
 - Termination: Ends when replication forks meet or reach telomeres.
 - Telomeres: Repeated DNA sequences at chromosome ends.
 - Telomerase: Enzyme that rebuilds telomeres.
 - Proofreading: DNA polymerase corrects errors during replication.
 🧬 Protein Synthesis
 
 Transcription (DNA → RNA)
 - Sense strand: The DNA strand not transcribed.
 - Antisense strand: The template strand for RNA synthesis.
 - TATA box: Promoter region where transcription begins.
 - Initiation: RNA polymerase binds to promoter with help of transcription factors.
 - Elongation: RNA polymerase builds pre-mRNA.
 - Termination: RNA polymerase stops at termination sequence.
 - RNA processing:
 
 5' cap: Added for stability and ribosome binding.
 
 3' poly-A tail: Helps with nuclear export and protection.
 
 Introns: Non-coding regions removed.
 
 Exons: Coding regions spliced together.
 
 Spliceosome: Complex that removes introns.
 - One gene–one enzyme hypothesis: Each gene codes for one enzyme/protein.
 Translation (mRNA → Protein)
 - Initiation:
 
 Small ribosomal subunit binds mRNA.
 
 First tRNA binds to start codon (AUG).
 
 Large subunit attaches; start at P site.
 - Elongation:
 
 New tRNA enters A site.
 
 Peptide bond formed between amino acids in P and A sites.
 
 Ribosome shifts; tRNA exits from E site.
 - Termination:
 
 Stop codon reached (UAA, UAG, UGA).
 
 Release factor frees polypeptide.
 - Codon: 3-nucleotide mRNA sequence.
 - Anticodon: 3-nucleotide tRNA sequence.
 - Polyribosome: Multiple ribosomes translating one mRNA.
 🧬 Mutations
 - Somatic mutation: In body cells (not passed on).
 - Germline mutation: In gametes (heritable).
 - Point mutation: Single nucleotide change.
 
 Silent: No change in protein.
 
 Missense: Changes one amino acid.
 
 Nonsense: Creates a stop codon.
 - Frameshift: Insertion or deletion shifts reading frame.
 - Chromosomal mutations: Affect entire sections (duplications, inversions, etc.).
 - Transposons: Jumping genes; moved by transposase.
 - Mutagens:
 
 Physical: UV rays, X-rays
 
 Chemical: Base analogs, carcinogens
 - AMES test: Detects mutagenic chemicals.
 - DNA repair:
 
 Direct: Fixes damage directly.
 
 Excision: Removes damaged DNA and replaces it.
 
 Recombinant: Uses homologous DNA to fix damage.
 - Suicide genes: Trigger cell death if damage is too severe.
 🧬 Gene Expression & Regulation
 - Operon: Cluster of genes controlled by one promoter (mostly in bacteria).
 
 Operator: DNA segment where repressor binds.
 
 Inducer: Molecule that deactivates the repressor.
 
 Repressor: Protein that blocks transcription.
 
 Inducible operon (lac operon): Normally off, turns on in presence of lactose.
 
 Co-repressor (trp operon): Helps turn operon off when enough product is made.
 
 CAP + cAMP: Positive regulation for increasing transcription when glucose is low.
 - Levels of control:
 
 Pre-transcriptional: Chromatin remodeling, methylation.
 
 Transcriptional: Transcription factors control gene activation.
 
 Pre-translational: mRNA splicing, capping, tailing.
 
 Translational: mRNA stability, ribosome binding.
 
 Post-translational: Protein folding, modification.
 🧬 Gene Technology
 - Restriction endonucleases: Cut DNA at specific sequences (restriction sites).
 - Restriction fragments: Pieces of DNA after being cut.
 - Recombinant DNA: DNA combined from different organisms.
 - Bacterial vector cloning: Insert gene into plasmid → bacteria express it.
 - PCR (polymerase chain reaction): Rapid DNA amplification.
 - Gel electrophoresis: Separates DNA fragments by size.
 - Chain termination sequencing (Sanger): Uses fluorescent nucleotides to read DNA sequence.
 - Cloning: Making a genetically identical copy of a gene or organism.
 ORGANIZATION OF THE BODY
 - Cell → Tissue → Organ → Organ System → Organism
 - Homeostasis: The process of maintaining a stable internal environment (e.g., body temperature, blood sugar, pH).
 - Extracellular environment: Fluid outside of cells (e.g., plasma, interstitial fluid).
 🔄 FEEDBACK LOOPS
 - Negative feedback loop: Reverses a change to maintain stability (e.g., blood glucose, body temp).
 - Positive feedback loop: Enhances a change (e.g., childbirth, blood clotting).
 🧠 NERVOUS SYSTEM
 
 Structure & Function
 - Neuron: Basic unit of the nervous system.
 
 Dendrites: Receive signals
 
 Cell body: Contains nucleus
 
 Axon: Sends signals
 
 Myelin sheath: Insulates axon
 
 Schwann cells: Make myelin
 
 Nodes of Ranvier: Gaps in myelin that help speed signal
 
 Axon terminals: Pass signal to next neuron or muscle
 - Saltatory conduction: Signal jumps from node to node for faster transmission.
 Nervous System Organization
 - Central Nervous System (CNS): Brain and spinal cord
 - Peripheral Nervous System (PNS):
 
 Somatic NS: Voluntary (skeletal muscles)
 
 Autonomic NS: Involuntary
 
 Sympathetic: “Fight or flight”
 
 Parasympathetic: “Rest and digest”
 Neuron Communication
 - Receptor → Afferent neuron (sensory) → Integrator (CNS) → Efferent neuron (motor) → Effector (muscle/gland)
 - Association neurons (interneurons): Connect sensory and motor neurons within CNS.
 - Synapse: Gap between neurons.
 
 Presynaptic membrane: Sends neurotransmitters
 
 Postsynaptic membrane: Receives them
 
 Neurotransmitters: Chemical messengers (e.g., acetylcholine)
 
 Cholinesterase: Breaks down neurotransmitters
 Nerve Impulse Terms
 - Resting potential: ~ -70mV (inside is negative)
 - Threshold potential: Minimum stimulus needed to trigger an action potential.
 - Depolarization: Na⁺ enters → inside becomes positive.
 - Repolarization: K⁺ exits → restores negative charge.
 - Refractory period: Brief time when neuron can't fire again.
 - Voltage-gated channels: Open based on membrane charge.
 - Na⁺/K⁺ pump: Restores original ion positions (3 Na⁺ out, 2 K⁺ in).
 Reflexes
 - Reflex arc: Involuntary response (e.g., pulling away from a hot surface).
 - Classical conditioning: Learned response via repeated exposure.
 🧠 BRAIN STRUCTURE
 - Hypothalamus: Homeostasis control (temp, hunger, hormones).
 - Pituitary gland: Master gland; controls other glands.
 - Corpus callosum: Connects left/right brain.
 - Frontal lobe: Decision making, movement.
 - Parietal lobe: Sensory input.
 - Temporal lobe: Hearing, memory.
 - Occipital lobe: Vision.
 🧪 HORMONES & GLANDS
 
 Gland Types
 - Endocrine: Secretes hormones into blood (e.g., pituitary).
 - Exocrine: Secretes into ducts (e.g., sweat glands).
 Hormone Types
 - Steroid hormones: Fat-soluble, enter cells (e.g., estrogen).
 - Non-steroid hormones: Bind outside cell and use secondary messengers (e.g., insulin).
 Pituitary Gland
 - Anterior: Makes and releases hormones (e.g., GH, TSH).
 - Posterior: Releases hormones made by hypothalamus (e.g., ADH).
 🛡️ IMMUNE SYSTEM
 
 First Line (Non-Specific)
 - Skin, mucous, stomach acid
 Second Line (Non-Specific)
 - Phagocytes/macrophages: Engulf pathogens (phagocytosis)
 - Natural killer cells: Kill infected or cancer cells
 - Inflammation: Caused by histamine
 - Histamine: Increases blood flow to site
 - Antihistamines: Block allergic response
 Third Line (Specific Immunity)
 - T cells (cellular immunity):
 
 Helper T cells: Activate other immune cells
 
 Memory T cells: Remember pathogens
 - B cells (antibody immunity):
 
 Plasma cells: Make antibodies
 
 Memory B cells: Long-term protection
 - Antigen: Marker on pathogen
 - Antibody: Protein that binds to antigen
 - Clonal expansion: Rapid cell division when antigen is detected
 - Self vs Non-self: Body identifies and attacks only foreign invaders
 - Specificity & Diversity: Antibodies are tailored to antigens
 Disorders and Responses
 - Vaccines: Expose body to antigens without disease.
 - Allergies: Overreaction to harmless substances
 
 Immediate: Fast (e.g., peanuts)
 
 Delayed: Slower (e.g., poison ivy)
 - Chemotherapy: Targets rapidly dividing cells.
 - Differentiation: Cells become specialized.
 - Cancer: Uncontrolled cell division.
 💧 OSMOREGULATION & KIDNEYS
 - Osmoregulation: Balancing water and salt in the body.
 - Tonicity:
 
 Hypotonic: Lower solute outside → water in
 
 Hypertonic: Higher solute outside → water out
 
 Isotonic: Equal solute
 Hormones
 - ADH (antidiuretic hormone): Increases water reabsorption in kidneys.
 Filtration
 - 3 Factors:
 
 Blood pressure
 
 Membrane permeability
 
 Concentration gradient
 - Dialysis filter:
 
 Small molecules (urea, ions) pass
 
 Large molecules (proteins, blood cells) can’t
 🍬 BLOOD GLUCOSE REGULATION
 - Pancreas: Regulates glucose
 
 Beta cells: Make insulin → lowers blood glucose
 
 Alpha cells: Make glucagon → raises blood glucose
 
 Islets of Langerhans: Clusters of hormone-producing cells
 Diabetes
 - Type 1: Autoimmune, no insulin made
 - Type 2: Insulin resistance, often lifestyle-related
 📊 Diagrams to Know
 1. Basic neuron
 2. Synapse handout
 3. Human Nervous System flow chart
 4. Main immune system players
 5. Blood glucose regulation chart

Protein Structure Overview

Overview

Protein Basics

Amino Acid Structure

Peptide Bond Formation

Levels of Protein Structure

Key Terms & Definitions

Action Items / Next Steps

<span>🔬 Glycolysis</span>

<span>🔁 Transition Reactions & Krebs Cycle (Citric Acid Cycle)</span>

<span>⚡ Electron Transport Chain (ETC) & ATP Production</span>

<span>🌱 Photosynthesis</span>

<span>Key Terms and Concepts</span>

<span>Atoms and Bonds</span>

<span>Acids, Bases, pH</span>

<span>🍔 Macromolecules (Know structures and functions)</span>

<span>Carbohydrates</span>

<span>Proteins</span>

<span>Nucleic Acids</span>

<span>🔄 Reactions & Enzymes</span>

<span>⚡ Energy and Thermodynamics</span>

<span>🧪 Functional Groups (Be able to recognize and name):</span>

<span>🧫 Cell Membranes and Transport</span>

<span>🔁 Metabolism</span>

<span>💡 Examples & Applications</span>

<span>People to Know</span>

<span>🧪 DNA & RNA Structure</span>

<span>🔬 Prokaryotes vs Eukaryotes</span>

<span>📚 DNA vs RNA</span>

<span>🧬 DNA Replication</span>

<span>🧬 Protein Synthesis</span>

<span>Transcription (DNA → RNA)</span>

<span>Translation (mRNA → Protein)</span>

<span>🧬 Mutations</span>

<span>🧬 Gene Expression & Regulation</span>

<span>🧬 Gene Technology</span>

<span>ORGANIZATION OF THE BODY</span>

<span>🔄 FEEDBACK LOOPS</span>

<span>🧠 NERVOUS SYSTEM</span>

<span>Structure & Function</span>

<span>Nervous System Organization</span>

<span>Neuron Communication</span>

<span>Nerve Impulse Terms</span>

<span>Reflexes</span>

<span>🧠 BRAIN STRUCTURE</span>

<span>🧪 HORMONES & GLANDS</span>

<span>Gland Types</span>

<span>Hormone Types</span>

<span>Pituitary Gland</span>

<span>🛡️ IMMUNE SYSTEM</span>

<span>First Line (Non-Specific)</span>

<span>Second Line (Non-Specific)</span>

<span>Third Line (Specific Immunity)</span>

<span>Disorders and Responses</span>

<span>💧 OSMOREGULATION & KIDNEYS</span>

<span>Hormones</span>

<span>Filtration</span>

<span>🍬 BLOOD GLUCOSE REGULATION</span>

<span>Diabetes</span>

<span>📊 Diagrams to Know</span>