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. This process forms polymers from monomers.

• Hydrolysis Reaction: A chemical reaction that breaks a bond in a molecule by adding water, splitting polymers into monomers.

• Comparison: Dehydration builds molecules up, hydrolysis breaks them down.

• Example: Formation and breakdown of polysaccharides, proteins, and nucleic acids.

Transcription vs. Translation

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

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

• Comparison: Transcription makes RNA, translation makes protein.

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 a DNA template during transcription.

• Ribosomes: Sites of protein synthesis; facilitate the translation of mRNA into polypeptides.

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 an mRNA codon.

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

Mutations: Point, Insertion, Deletion

• 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 gene function, possibly causing frameshifts (insertions/deletions) or silent/missense/nonsense mutations (point mutations).

Introns, Exons, and Splicing

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

• Exons: Coding regions that remain in mature mRNA.

• Splicing: Process of removing introns and joining exons to produce mature mRNA.

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 (simple sugars, e.g., glucose).

Polysaccharides: Starch, Glycogen, Chitin, Cellulose

Polysaccharide	Function	Organism
Starch	Energy storage	Plants
Glycogen	Energy storage	Animals
Chitin	Structural (exoskeletons, cell walls)	Arthropods, fungi
Cellulose	Structural (cell walls)	Plants

Lipids

Elements and Types

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

• Types: Fatty acids, steroids, triglycerides, phospholipids.

Fatty Acids, Steroids, Triglycerides, Phospholipids

Type	Structure	Function
Fatty Acids	Long hydrocarbon chains	Energy storage, building blocks
Steroids	Four fused rings	Hormones, membrane structure
Triglycerides	Glycerol + 3 fatty acids	Energy storage
Phospholipids	Glycerol + 2 fatty acids + phosphate	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.

Levels of Protein Structure

• Primary: Sequence of amino acids.

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

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

• Quaternary: Multiple polypeptide chains assembled together.

Nucleic Acids

Elements, Types, and Structure

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

• Types: DNA and RNA.

• Monomers: Nucleotides.

• Nucleotide Components: Phosphate group, sugar (deoxyribose or ribose), nitrogenous base.

DNA vs. RNA

Feature	DNA	RNA
Sugar	Deoxyribose	Ribose
Bases	A, T, C, G	A, U, C, G
Strands	Double	Single
Function	Genetic storage	Protein synthesis, regulation

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 or RNA.

• Chromosome: Structure of DNA and proteins carrying many genes.

Semiconservative Replication

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

Famous Scientists

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

• 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: Principles of geology; Earth's age and gradual change.

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

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

• Frederick Griffith: Transformation in bacteria.

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

• Phoebus Levene: Identified nucleotide structure.

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

Solutions & Membrane Transport

Hypertonic, Hypotonic, Isotonic Solutions

• 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: Movement down concentration gradient; no energy required (e.g., diffusion, osmosis).

• Active Transport: Movement against gradient; requires energy (ATP).

Role of Membranes and Proteins

• Membranes regulate entry/exit; 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, membrane-bound organelles (e.g., plants, animals).

Animal vs. Plant Cells

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

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

Cell Structures and Organelles

• Cell Membrane: Phospholipid bilayer; regulates transport.

• Cell Wall: Structural 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, packages 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 (cell division).

• 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 (thylakoid membranes for light reactions, stroma for dark reactions).

• 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 a proton gradient across the thylakoid membrane.

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

• Electron Transporters: Plastoquinone, plastocyanin, ferredoxin.

Cellular Respiration

• Location: Mitochondria (glycolysis in cytoplasm, Krebs cycle in matrix, ETC in inner membrane).

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

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

• Glycolysis: Cytoplasm; inputs: glucose; outputs: pyruvate, ATP, NADH.

• Citric Acid Cycle: Mitochondrial matrix; inputs: acetyl-CoA; outputs: CO2, NADH, FADH2, ATP.

• Electron Transport Chain: Inner mitochondrial membrane; electrons from NADH/FADH2 to O2.

• ATP Synthase: Uses proton gradient to make ATP.

• Fermentation: Anaerobic process; regenerates NAD+ (e.g., lactic acid, ethanol).

• Electron Donors: NADH, FADH2; Final Acceptor: O2.

• Electron Transporters: NADH, FADH2, cytochromes.

Cellular Reproduction

Mitosis Stages

1. Prophase: Chromosomes condense, spindle forms.

2. Metaphase: Chromosomes align at cell equator.

3. Anaphase: Sister chromatids separate.

4. Telophase: Nuclear envelopes reform, chromosomes decondense.

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 is similar to mitosis.

Haploid vs. Diploid, Gamete vs. Zygote

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

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

• Gamete: Sperm or egg.

• Zygote: Fertilized egg.

Binary Fission

• Simple cell division 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; Veins: To heart; Capillaries: Exchange.

• Capillary Recovery: Lymphatic system returns 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, etc.), kidneys.

• Estrogen/Progesterone: Regulate female reproductive cycle; low = menstruation, high = pregnancy maintenance.

• Adrenal Medulla: Produces adrenaline; responds to stress.

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

Immune System

• Antibody: Protein that binds antigens.

• Antigen: Foreign molecule triggering immune response.

• Microbe: Microscopic organism.

• Virus: Infectious agent; not cellular.

• Memory Cells: Long-lived immune cells.

• Histamine: Inflammatory mediator.

• B Cells: Produce antibodies.

• T Cells: Kill infected cells, regulate immunity.

• Macrophages: Engulf pathogens.

Digestive System

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

• Main Functions: Mouth (chewing, amylase), stomach (acid, digestion), small intestine (absorption), large intestine (water absorption).

• Amylase: Enzyme for starch digestion.

• Bile Salts: Emulsify fats.

• Chyme: Partially digested food in stomach.

• Heartburn: Acid reflux.

• Gastric Acid: Stomach acid (HCl).

• 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 transmitting nerve signals.

• Phases: Resting potential (Na+/K+ gradients), depolarization (Na+ influx), repolarization (K+ efflux), refractory period (resetting).

Genetics & Population Biology

Hardy-Weinberg Equation

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

• 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

• Determine gametes, set up grid for monohybrid/dihybrid crosses.

• Calculate genotype and phenotype probabilities.

• Interpret pedigrees/family trees for inheritance patterns.

Chi Squared Analysis

• Statistical test for observed vs. expected data.

• Degrees of Freedom: Number of categories minus one.

The Environment & Scientific Thinking

Scientific Method

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

• Hypothesis: Testable, falsifiable statement.

Ecosystems & Habitats

• Major types: Forest, desert, grassland, aquatic, tundra; each with unique features (e.g., rainfall, temperature).

Ozone Layer

• Protects Earth from UV radiation.

Rain Shadow

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

Temperature & Seasons

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

Hierarchy of Biological Organization

• Molecule → Organelle → Cell → Tissue → Organ → Organ System → Organism → Population → Community → Ecosystem → Biosphere