Comprehensive Biology Final Exam Study Guide

Macromolecules & Gene Expression

Dehydration vs. Hydrolysis Reactions

• Dehydration Reaction: A chemical reaction that joins two molecules by removing a water molecule. Used to build polymers from monomers.

• Hydrolysis Reaction: A chemical reaction that breaks a bond in a molecule by adding water. Used to break down polymers into monomers.

• Comparison: Dehydration synthesizes, hydrolysis degrades; both are catalyzed by specific enzymes.

Transcription vs. Translation

• Transcription: Synthesis of RNA from a DNA template; occurs in the nucleus (eukaryotes).

• Translation: Synthesis of a polypeptide using mRNA as a template; occurs in the cytoplasm at ribosomes.

Roles of mRNA, tRNA, Polymerase, and Ribosomes

• mRNA (messenger RNA): Carries genetic code from DNA to ribosomes.

• tRNA (transfer RNA): Brings amino acids to ribosomes during translation.

• RNA Polymerase: Enzyme that synthesizes RNA from DNA during transcription.

• Ribosomes: Sites of protein synthesis; composed of rRNA and proteins.

Codons and Anticodons

• Codon: A sequence of three mRNA nucleotides that codes for a specific amino acid.

• Anticodon: A sequence of three nucleotides on tRNA complementary to the mRNA codon.

• Codon Table: Used to determine which amino acid corresponds to each codon.

Mutations

• Point Mutation: Change in a single nucleotide.

• Insertion Mutation: Addition of one or more nucleotides.

• Deletion Mutation: Removal of one or more nucleotides.

• Effects: Can alter protein structure/function; insertions/deletions may cause frameshifts.

Introns, Exons, and Splicing

• Introns: Non-coding regions of a gene; removed during RNA processing.

• Exons: Coding regions; joined together to form mature mRNA.

• Splicing: Process of removing introns and joining exons.

Carbohydrates

Elements and Structure

• Elements: Carbon (C), Hydrogen (H), Oxygen (O) in a 1:2:1 ratio (C:H:O).

• Naming: Often end in "-ose" (e.g., glucose, fructose).

• Monomers: Monosaccharides (e.g., glucose).

Polysaccharides

• Starch: Energy storage in plants.

• Glycogen: Energy storage in animals.

• Chitin: Structural component in arthropod exoskeletons and fungal cell walls.

• Cellulose: Structural component in plant cell walls.

Lipids

Elements and Types

• Elements: Carbon, Hydrogen, Oxygen (less O than carbohydrates).

• Fatty Acids: Long hydrocarbon chains; can be saturated or unsaturated.

• Steroids: Four fused carbon rings (e.g., cholesterol).

• Triglycerides: Glycerol + 3 fatty acids; main energy storage.

• Phospholipids: Glycerol + 2 fatty acids + phosphate group; main component of cell membranes.

Saturated vs. Unsaturated Fatty Acids

• Saturated: No double bonds; solid at room temperature; higher melting point.

• Unsaturated: One or more double bonds; liquid at room temperature; lower melting point.

HDL and LDL

• HDL (High-Density Lipoprotein): "Good" cholesterol; removes cholesterol from blood.

• LDL (Low-Density Lipoprotein): "Bad" cholesterol; deposits cholesterol in arteries.

Proteins

Elements and Structure

• Elements: Carbon, Hydrogen, Oxygen, Nitrogen (sometimes Sulfur).

• Monomers: Amino acids.

• Primary Structure: Sequence of amino acids.

• Secondary Structure: Alpha helices and beta sheets (hydrogen bonding).

• Tertiary Structure: 3D folding due to side chain interactions.

• Quaternary Structure: Multiple polypeptide chains assembled together.

Nucleic Acids

Elements and Types

• Elements: Carbon, Hydrogen, Oxygen, Nitrogen, Phosphorus.

• Types: DNA and RNA.

• Monomers: Nucleotides.

• Nucleotide Components: Phosphate group, pentose sugar, nitrogenous base.

DNA vs. RNA

• DNA: Double-stranded, deoxyribose sugar, bases A, T, C, G.

• RNA: Single-stranded, ribose sugar, bases A, U, C, G.

Base Pairing Rules

• A pairs with T (or U in RNA), C pairs with G.

Chromosomes, Genes, and DNA

• DNA: Molecule carrying genetic information.

• Gene: Segment of DNA coding for a protein.

• Chromosome: Structure containing DNA and proteins; carries many genes.

Semiconservative Replication

• Each new DNA molecule consists of one old and one new strand.

Famous Scientists

• Alfred Hershey & Martha Chase: Proved DNA is genetic material using bacteriophages.

• Charles Darwin & Alfred Russell Wallace: Developed theory of evolution by natural selection.

• Thomas Malthus: Influenced Darwin; population growth and resource limits.

• Jean-Baptiste Lamarck: Early theory of evolution; inheritance of acquired traits.

• Charles Lyell: Uniformitarianism; Earth's processes are gradual.

• Erwin Chargaff: Base pairing rules (A=T, C=G).

• Rosalind Franklin: X-ray diffraction images of DNA.

• Frederick Griffith: Discovered transformation in bacteria.

• Oswald Avery & Maclyn MacLeod: Identified DNA as transforming principle.

• Phoebus Levene: Identified components of nucleic acids.

• Francis Crick & James Watson: Discovered double helix structure of DNA.

Solutions & Transport

Osmosis and Tonicity

• Hypertonic: Higher solute concentration outside cell; water leaves cell.

• Hypotonic: Lower solute concentration outside cell; water enters cell.

• Isotonic: Equal solute concentration; no net water movement.

Passive vs. Active Transport

• Passive Transport: No energy required; moves down concentration gradient (e.g., diffusion, osmosis).

• Active Transport: Requires energy (ATP); moves against concentration gradient.

Membranes and Proteins in Transport

• Membranes are selectively permeable; proteins facilitate transport (channels, carriers, pumps).

Cells & Their Machinery

Prokaryotic vs. Eukaryotic Cells

• Prokaryotic: No nucleus, no membrane-bound organelles (e.g., bacteria).

• Eukaryotic: Nucleus and membrane-bound organelles (e.g., plants, animals).

Animal vs. Plant Cells

• Plant Cells: Cell wall, chloroplasts, large central vacuole.

• Animal Cells: No cell wall or chloroplasts, small vacuoles, centrioles.

Cell Structures and Organelles

• Cell Membrane: Phospholipid bilayer; regulates entry/exit.

• Cell Wall: Rigid support (plants, fungi, bacteria).

• Cell Plate: Forms during plant cell division.

• Cytoplasm: Fluid matrix inside cell.

• Cytoskeleton: Structural support; movement.

• Nucleus: Contains DNA.

• Nucleolus: Ribosome synthesis.

• Nuclear Envelope: Double membrane around nucleus.

• Ribosome: Protein synthesis.

• Rough ER: Protein synthesis (with ribosomes).

• Smooth ER: Lipid synthesis, detoxification.

• Golgi Apparatus: Modifies, sorts, ships proteins/lipids.

• Mitochondrion: Cellular respiration; ATP production.

• Chloroplast: Photosynthesis (plants/algae).

• Vacuole: Storage (large in plants).

• Vesicle: Transport within cells.

• Lysosome: Digestion of macromolecules.

• Peroxisome: Breaks down fatty acids, detoxifies.

• Centriole/Centrosome: Organizes microtubules (animal cells).

• Cilia/Flagellum: Movement.

• Microtubules, Microfilaments, Intermediate Filaments: Cytoskeletal elements.

Endosymbiotic Theory

• Mitochondria and chloroplasts originated as free-living prokaryotes engulfed by ancestral eukaryotes.

• Evidence: Double membranes, own DNA, ribosomes similar to bacteria.

Electron Microscopy

• Scanning Electron Microscope (SEM): Surface details, 3D images.

• Transmission Electron Microscope (TEM): Internal structures, thin sections.

Energetics

Photosynthesis

• Location: Chloroplasts (plants, algae).

• Key Structures: Thylakoids, grana, stroma.

• Light Reactions: Produce ATP, NADPH, O2.

• Dark Reactions (Calvin Cycle): Produce glucose from CO2.

• Equation: $6CO_2 + 6H_2O + light \rightarrow C_6H_{12}O_6 + 6O_2$

• ATP Synthase: Enzyme that synthesizes ATP using proton gradient across thylakoid membrane.

• Electron Flow: Water donates electrons; NADP+ is final acceptor.

• Electron Transporters: Plastoquinone, plastocyanin, ferredoxin.

Cellular Respiration

• Location: Mitochondria (eukaryotes).

• Key Structures: Outer membrane, inner membrane, cristae, matrix.

• Equation: $C_6H_{12}O_6 + 6O_2 \rightarrow 6CO_2 + 6H_2O + ATP$

• Glycolysis: Cytoplasm; glucose to pyruvate.

• Citric Acid Cycle: Mitochondrial matrix; completes glucose breakdown.

• Electron Transport Chain: Inner mitochondrial membrane; produces most ATP.

• ATP Synthase: Uses proton gradient to make ATP.

• Fermentation: Anaerobic process; regenerates NAD+.

• Inputs/Outputs:

  • Glycolysis: Glucose → 2 pyruvate, 2 ATP, 2 NADH

  • Citric Acid Cycle: Acetyl-CoA → CO2, NADH, FADH2, ATP

• Electron Flow: NADH/FADH2 donate electrons; O2 is final acceptor.

• Electron Transporters: NADH, FADH2, cytochromes.

Cellular Reproduction

Mitosis Stages

• Prophase: Chromosomes condense, spindle forms.

• Metaphase: Chromosomes align at cell equator.

• Anaphase: Sister chromatids separate.

• Telophase: Nuclear envelopes reform, chromosomes decondense.

• Cytokinesis: Division of cytoplasm.

Interphase

• Cell grows, DNA replicates, prepares for division.

Mitosis vs. Meiosis

• Mitosis: One division, two identical diploid cells.

• Meiosis: Two divisions, four non-identical haploid cells; Meiosis II resembles mitosis.

Haploid vs. Diploid

• Haploid (n): One set of chromosomes (gametes).

• Diploid (2n): Two sets (somatic cells).

• Gamete: Sex cell (sperm/egg).

• Zygote: Fertilized egg (diploid).

Binary Fission

• Asexual reproduction in prokaryotes; produces two identical cells.

Products of Mitosis and Meiosis

• Mitosis: 2 diploid cells.

• Meiosis: 4 haploid cells.

Anatomy & Physiology

Roles of Fe, Ca, Na, K

• Fe (Iron): Oxygen transport (hemoglobin).

• Ca (Calcium): Bone structure, muscle contraction.

• Na (Sodium): Nerve impulses, fluid balance.

• K (Potassium): Nerve impulses, muscle function.

Cardiovascular System

• Major Organs: Heart (RA, RV, LA, LV), blood vessels, lungs.

• Blood Flow: RA → RV → lungs → LA → LV → body.

• S/A Node: Pacemaker; initiates heartbeat.

• Blood Components: Plasma, red cells, white cells, platelets.

• Arteries: Carry blood away from heart; thick walls.

• Veins: Carry blood to heart; valves present.

• Capillaries: Exchange of gases/nutrients.

• Lymphatic System: Recovers leaked fluid.

• Blood Pressure: Systolic/diastolic; force of blood on vessel walls.

• ECG/EKG: Measures electrical activity of heart.

Endocrine System (and Renal)

• Major Organs: Glands (pituitary, adrenal, pancreas, etc.).

• Estrogen/Progesterone: Regulate female reproductive cycle; low levels trigger menstruation, high levels maintain pregnancy.

• Adrenal Medulla: Secretes adrenaline; responds to stress.

• Water Retention Hormones: ADH, aldosterone; increase water reabsorption in kidneys.

Immune System

• Antibody: Protein that binds antigens.

• Antigen: Foreign molecule that triggers immune response.

• Microbe: Microscopic organism (bacteria, virus, etc.).

• Virus: Non-living infectious agent; needs host cell.

• Memory Cells: Long-lived cells for faster future response.

• Histamine: Inflammatory mediator.

• B Cells: Produce antibodies.

• T Cells: Kill infected cells, regulate immune response.

• Macrophages: Engulf pathogens.

Digestive System

• Path of Food: Mouth → esophagus → stomach → small intestine → large intestine → rectum → anus.

• Main Functions:

  • Mouth: Mechanical/chemical digestion (amylase).

  • Stomach: Protein digestion (gastric acid, chyme).

  • Small Intestine: Nutrient absorption.

  • Large Intestine: Water absorption.

• Amylase: Enzyme for starch digestion.

• Bile Salts: Emulsify fats.

• Chyme: Partially digested food in stomach.

• Heartburn: Acid reflux into esophagus.

• Vitamin C: Collagen synthesis; water-soluble.

• Vitamin K: Blood clotting; fat-soluble.

Nervous System

• Major Organs: Brain, spinal cord, nerves.

• Action Potential: Rapid change in membrane potential; nerve impulse.

• Phases:

  • Resting Potential: -70 mV; Na+/K+ gradients maintained.

  • Depolarization: Na+ influx.

  • Repolarization: K+ efflux.

  • Refractory Period: Membrane resets; cannot fire again immediately.

Genetics & Population Biology

Hardy-Weinberg Equation

• Equations: $p^2 + 2pq + q^2 = 1$ $p + q = 1$

• Terms: p = frequency of dominant allele, q = frequency of recessive allele.

• Conditions: Large population, random mating, no mutation, migration, or selection.

• Shifts: Mutation, migration, selection, genetic drift, non-random mating.

Punnett Squares

• Used to predict genotype and phenotype ratios from parental crosses.

• Monohybrid Cross: One gene; 3:1 ratio (dominant:recessive) in F2.

• Dihybrid Cross: Two genes; 9:3:3:1 ratio in F2.

• Pedigrees: Family trees to track inheritance patterns.

Chi Squared Analysis

• Statistical test to compare observed vs. expected results.

• Degrees of Freedom: Number of categories minus one.

The Environment & Scientific Thinking

Scientific Method

• Steps: Observation, question, hypothesis, experiment, analysis, conclusion.

• Hypothesis: Testable, falsifiable statement.

Ecosystems & Habitats

• Major types: Forest, desert, grassland, aquatic, tundra; each with unique climate and organisms.

Ozone Layer

• Protects Earth from UV radiation.

Rain Shadow

• Dry area on leeward side of mountain due to loss of moisture on windward side.

Temperature & Seasons

• Caused by Earth's tilt and orbit; equator receives more direct sunlight than poles.

Hierarchy of Structures

• Molecules → Organelles → Cells → Tissues → Organs → Organ Systems → Organism → Population → Community → Ecosystem → Biosphere