BackBIO-157 General Biology I: Comprehensive Study Guide (Chapters 1–21, Excluding Chapter 11)
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Chapter 1: Evolution, the Themes of Biology, and Scientific Inquiry
Overview of Biological Organization and Scientific Method
Levels of Biological Organization: Life is organized from the biosphere down to molecules (biosphere, ecosystem, community, population, organism, organ system, organ, tissue, cell, organelle, molecule).
Properties of Life: Includes order, reproduction, growth and development, energy processing, response to environment, regulation, and evolutionary adaptation.
Emergent Properties: New properties arise at each level of organization due to the arrangement and interactions of parts.
Scientific Method: Involves observation, hypothesis formation, prediction, experimentation, and conclusion.
Controlled Experiments: Only one variable is changed at a time to test a hypothesis.
Themes in Biology: Evolution, structure and function, information flow, energy transfer, and interactions.
Example: The adaptation of finch beaks on the Galápagos Islands demonstrates evolution by natural selection.
Chapter 2: The Chemical Context of Life
Atoms, Elements, and Chemical Bonds
Atomic Structure: Atoms consist of protons, neutrons, and electrons. Atomic number = number of protons; mass number = protons + neutrons.
Elements and Compounds: Elements are pure substances; compounds are combinations of two or more elements in fixed ratios.
Types of Bonds: Covalent (sharing electrons), ionic (transfer of electrons), hydrogen bonds, and van der Waals interactions.
Isotopes: Atoms of the same element with different numbers of neutrons.
Chemical Reactions: Making and breaking of chemical bonds; matter is conserved.
Example: Water (H2O) is a compound formed by covalent bonds between hydrogen and oxygen.
Chapter 3: Water and Life
Properties and Importance of Water
Polarity: Water is a polar molecule, leading to hydrogen bonding.
Cohesion and Adhesion: Cohesion is the attraction between water molecules; adhesion is attraction to other substances.
Temperature Moderation: Water has high specific heat and heat of vaporization, stabilizing temperatures.
Solvent Properties: Water dissolves many substances due to its polarity ("universal solvent").
Density: Ice is less dense than liquid water due to hydrogen bonding.
Acids, Bases, and pH: pH measures hydrogen ion concentration; water can dissociate into H+ and OH-.
Example: Water's high heat capacity helps organisms maintain stable internal temperatures.
Chapter 4: Carbon and the Molecular Diversity of Life
Carbon Chemistry and Functional Groups
Bonding Versatility: Carbon forms four covalent bonds, allowing for diverse molecules (chains, rings, branching).
Isomers: Compounds with the same formula but different structures (structural, cis-trans, enantiomers).
Functional Groups: Groups of atoms that confer specific properties (hydroxyl, carbonyl, carboxyl, amino, sulfhydryl, phosphate, methyl).
Significance: Functional groups determine the chemical reactivity and function of organic molecules.
Example: The presence of a carboxyl group makes amino acids acidic.
Chapter 5: The Structure and Function of Large Biological Molecules
Macromolecules: Carbohydrates, Lipids, Proteins, Nucleic Acids
Polymers and Monomers: Carbohydrates, proteins, and nucleic acids are polymers made of monomers; lipids are not true polymers.
Dehydration Synthesis and Hydrolysis: Dehydration joins monomers; hydrolysis breaks them apart.
Carbohydrates: Monosaccharides (glucose), disaccharides (sucrose), polysaccharides (starch, cellulose, glycogen).
Lipids: Fats, phospholipids, steroids; hydrophobic; important for energy storage and membranes.
Proteins: Polymers of amino acids; structure determines function; levels of structure (primary, secondary, tertiary, quaternary); denaturation disrupts structure.
Nucleic Acids: DNA and RNA; made of nucleotides; store and transmit genetic information.
Example: Enzymes are proteins that catalyze biochemical reactions.
Chapter 6: A Tour of the Cell
Cell Structure and Function
Prokaryotic vs. Eukaryotic Cells: Prokaryotes lack a nucleus and membrane-bound organelles; eukaryotes have both.
Cell Size: Surface area-to-volume ratio limits cell size.
Organelles: Nucleus, ribosomes, endoplasmic reticulum (ER), Golgi apparatus, lysosomes, mitochondria, chloroplasts, vacuoles.
Cytoskeleton: Microtubules, microfilaments, intermediate filaments; provide structure and facilitate movement.
Endosymbiotic Theory: Mitochondria and chloroplasts originated from engulfed prokaryotes.
Example: Mitochondria are the site of cellular respiration in eukaryotic cells.
Chapter 7: Membrane Structure and Function
Plasma Membrane Dynamics
Fluid Mosaic Model: Membrane is a fluid structure with proteins embedded in a phospholipid bilayer.
Phospholipid Bilayer: Hydrophilic heads face outward; hydrophobic tails face inward.
Membrane Proteins: Integral (span membrane) and peripheral (surface) proteins; functions include transport, signaling, and cell recognition.
Selective Permeability: Some substances cross more easily than others.
Transport Mechanisms: Passive (diffusion, osmosis, facilitated diffusion) and active (requires energy, e.g., pumps).
Tonicity: Hypotonic, isotonic, hypertonic solutions affect cell water balance.
Example: Sodium-potassium pump maintains ion gradients in animal cells.
Chapter 8: An Introduction to Metabolism
Energy and Enzymes in Biological Systems
Metabolism: All chemical reactions in an organism; divided into catabolic (breakdown) and anabolic (synthesis) pathways.
Energy: Kinetic (motion) and potential (stored); chemical energy in bonds.
Thermodynamics: First law (energy conservation), second law (entropy increases).
ATP: Main energy currency; hydrolysis releases energy for cellular work.
Enzymes: Biological catalysts; lower activation energy; affected by temperature, pH, inhibitors.
Example: Sucrase catalyzes the hydrolysis of sucrose into glucose and fructose.
Chapter 9: Cellular Respiration and Fermentation
Harvesting Chemical Energy
Cellular Respiration: Overall equation:
Stages: Glycolysis (cytoplasm), pyruvate oxidation, citric acid cycle (mitochondria), oxidative phosphorylation (electron transport chain and chemiosmosis).
Fermentation: Anaerobic process; produces less ATP; lactic acid and alcohol fermentation.
ATP Production: Most ATP generated by oxidative phosphorylation.
Example: Muscle cells use lactic acid fermentation when oxygen is scarce.
Chapter 10: Photosynthesis
Converting Light Energy to Chemical Energy
Photosynthesis Equation:
Light Reactions: Occur in thylakoid membranes; produce ATP and NADPH.
Calvin Cycle: Occurs in stroma; uses ATP and NADPH to fix CO2 into sugars.
Photosystems: Clusters of pigments that capture light energy.
C3, C4, and CAM Plants: Different strategies for carbon fixation and water conservation.
Example: Corn is a C4 plant, adapted to hot, dry environments.
Chapter 12: The Cell Cycle
Cell Division and Regulation
Phases: Interphase (G1, S, G2), M phase (mitosis and cytokinesis).
Mitosis: Prophase, metaphase, anaphase, telophase; produces genetically identical cells.
Cell Cycle Control: Checkpoints regulate progression; cyclins and cyclin-dependent kinases (CDKs) are key regulators.
Apoptosis: Programmed cell death; important for development and homeostasis.
Example: Cancer results from loss of cell cycle control.
Chapter 13: Meiosis and Sexual Life Cycles
Genetic Variation through Sexual Reproduction
Meiosis: Reduces chromosome number by half; produces gametes (sperm, eggs).
Stages: Meiosis I (homologous chromosomes separate), Meiosis II (sister chromatids separate).
Genetic Variation: Crossing over, independent assortment, random fertilization.
Life Cycles: Alternation of generations in plants; fungi and animals have different cycles.
Example: Genetic recombination during meiosis increases diversity in offspring.
Chapter 14: Mendel and the Gene Idea
Principles of Inheritance
Mendel's Laws: Law of segregation and law of independent assortment.
Genotype vs. Phenotype: Genotype is genetic makeup; phenotype is observable traits.
Dominant and Recessive Alleles: Dominant alleles mask recessive ones.
Punnett Squares: Tool for predicting genetic crosses.
Extensions: Incomplete dominance, codominance, multiple alleles, polygenic inheritance.
Example: Human blood types (A, B, AB, O) are determined by multiple alleles and codominance.
Chapter 15: The Chromosomal Basis of Inheritance
Genes and Chromosomes
Chromosome Theory: Genes are located on chromosomes.
Sex-Linked Traits: Genes on sex chromosomes (e.g., color blindness).
Linkage and Recombination: Linked genes are inherited together; crossing over produces recombinants.
Chromosomal Alterations: Deletions, duplications, inversions, translocations, nondisjunction (e.g., Down syndrome).
Example: Fruit fly eye color is a classic example of sex-linked inheritance.
Chapter 16: The Molecular Basis of Inheritance
DNA Structure and Replication
DNA Structure: Double helix, antiparallel strands, complementary base pairing (A-T, G-C).
Replication: Semi-conservative; involves enzymes like DNA polymerase, helicase, ligase.
Chromatin Structure: DNA wraps around histones to form nucleosomes; further packed into chromosomes.
Repair Mechanisms: Proofreading and repair enzymes correct errors.
Example: DNA polymerase adds nucleotides during replication and proofreads for errors.
Chapter 17: Gene Expression: From Gene to Protein
Transcription and Translation
Central Dogma: Information flows from DNA to RNA to protein.
Transcription: Synthesis of RNA from DNA template; occurs in the nucleus.
Translation: Synthesis of protein from mRNA; occurs at ribosomes.
Genetic Code: Triplet codons specify amino acids.
Mutations: Changes in DNA sequence can affect protein structure and function.
Example: Sickle cell anemia results from a single nucleotide mutation in the hemoglobin gene.
Chapter 18: Regulation of Gene Expression
Control of Gene Activity
Prokaryotic Regulation: Operons (e.g., lac operon) control gene clusters.
Eukaryotic Regulation: Transcription factors, enhancers, silencers, alternative splicing, epigenetic modifications (DNA methylation, histone modification).
Cell Differentiation: Differential gene expression produces different cell types.
Example: The trp operon in bacteria is repressed when tryptophan is abundant.
Chapter 19: Viruses
Structure and Function of Viruses
Structure: Genetic material (DNA or RNA), protein coat (capsid), sometimes an envelope.
Replication Cycles: Lytic (destroys host cell) and lysogenic (integrates into host genome).
Impact: Cause diseases in plants, animals, and bacteria; not considered living organisms.
Example: HIV is a retrovirus that infects human immune cells.
Chapter 20: DNA Tools and Biotechnology
Genetic Engineering and Applications
Restriction Enzymes: Cut DNA at specific sequences.
Gel Electrophoresis: Separates DNA fragments by size.
PCR (Polymerase Chain Reaction): Amplifies DNA sequences.
Cloning and Recombinant DNA: Inserting genes into vectors for expression in host cells.
Applications: Gene therapy, GMOs, forensic analysis.
Example: Insulin is produced by genetically engineered bacteria.
Chapter 21: Genomes and Their Evolution
Genome Organization and Evolutionary Insights
Genome Structure: Includes coding and noncoding DNA, repetitive sequences, transposable elements.
Comparative Genomics: Comparing genomes across species reveals evolutionary relationships.
Gene Families: Groups of related genes from duplication events.
Applications: Understanding evolution, disease, and development.
Example: The human genome contains many noncoding regions with regulatory functions.
General Study Tips
Focus on understanding processes, not just memorizing facts.
Make connections between chapters and concepts.
Use active recall: Test yourself without looking at notes.
Review previous chapter concepts as you progress.
