General Biology I: Comprehensive Final Exam Study Notes

Ch. 1: Introduction – Themes in the Study of Life

Classification of Living Organisms

Biologists classify all living organisms into three domains: Bacteria, Archaea, and Eukarya. This classification is based on cell type and genetic differences.

• Prokaryotes: Include Bacteria and Archaea; lack a nucleus and membrane-bound organelles.

• Eukaryotes: Include plants, animals, fungi, and protists; possess a nucleus and membrane-bound organelles.

Emergent properties arise at each level of biological organization, from molecules to biosphere.

Scientific inquiry involves observation, hypothesis formation, experimentation, and analysis.

Ch. 2: The Chemical Context of Life

Basic Chemical Principles

Life depends on chemical interactions among atoms and molecules.

• Elements: Substances that cannot be broken down chemically.

• Compounds: Substances formed from two or more elements.

• Chemical bonds: Include covalent, ionic, and hydrogen bonds.

Covalent bonds involve sharing of electrons; ionic bonds involve transfer of electrons; hydrogen bonds are weak attractions between polar molecules.

Ch. 3: Water and the Fitness of the Environment

Properties of Water

Water is essential for life due to its unique chemical and physical properties.

• Polarity: Water molecules have a partial positive and negative charge, allowing hydrogen bonding.

• Cohesion and adhesion: Water molecules stick to each other and to other surfaces.

• High specific heat: Water resists temperature changes.

• Solvent properties: Water dissolves many substances, facilitating chemical reactions.

Ch. 4: Carbon and the Molecular Diversity of Life

Carbon Compounds

Carbon forms the backbone of biological molecules due to its ability to form four covalent bonds.

• Organic molecules: Include carbohydrates, lipids, proteins, and nucleic acids.

• Isomers: Molecules with the same chemical formula but different structures.

Functional groups (e.g., hydroxyl, carboxyl, amino, phosphate) confer specific chemical properties.

Ch. 5: The Structure and Function of Large Biological Molecules

Macromolecules

Cells contain four major classes of macromolecules:

• Carbohydrates: Energy storage and structural support.

• Lipids: Energy storage, membrane structure, signaling.

• Proteins: Enzymes, structural components, transport, signaling.

• Nucleic acids: Store and transmit genetic information.

Macromolecules are formed by dehydration synthesis and broken down by hydrolysis.

Ch. 6: A Tour of the Cell

Cell Structure and Function

Cells are the basic unit of life, with specialized structures for different functions.

• Prokaryotic cells: Lack nucleus and membrane-bound organelles.

• Eukaryotic cells: Have nucleus, endoplasmic reticulum, Golgi apparatus, mitochondria, and other organelles.

Organelles compartmentalize cellular processes, increasing efficiency.

Ch. 7: Membrane Structure and Function

Cell Membranes

Cell membranes are composed of a phospholipid bilayer with embedded proteins.

• Fluid mosaic model: Describes the dynamic nature of membranes.

• Selective permeability: Membranes regulate the movement of substances in and out of cells.

• Transport mechanisms: Include passive transport (diffusion, osmosis) and active transport (requires energy).

Water balance is maintained through osmosis; cells may be in hypotonic, isotonic, or hypertonic solutions.

Ch. 8: An Introduction to Metabolism

Metabolic Pathways

Metabolism includes all chemical reactions in an organism, organized into metabolic pathways.

• Anabolic pathways: Build complex molecules from simpler ones (require energy).

• Catabolic pathways: Break down complex molecules into simpler ones (release energy).

• Enzymes: Biological catalysts that speed up reactions by lowering activation energy.

Environmental factors such as temperature and pH affect enzyme activity.

Ch. 9: Cellular Respiration and Fermentation

Energy Production in Cells

Cells extract energy from glucose through cellular respiration and fermentation.

• Glycolysis: Occurs in cytoplasm; breaks glucose into pyruvate.

• Krebs cycle (Citric Acid Cycle): Occurs in mitochondria; completes glucose breakdown.

• Electron transport chain: Produces most ATP via oxidative phosphorylation.

• Fermentation: Anaerobic process; produces less ATP.

Equation for cellular respiration: $\text{C}_6\text{H}_{12}\text{O}_6 + 6\text{O}_2 \rightarrow 6\text{CO}_2 + 6\text{H}_2\text{O} + \text{ATP}$

Ch. 10: Photosynthesis

Energy Capture in Plants

Photosynthesis converts light energy into chemical energy in plants, algae, and some bacteria.

• Light reactions: Capture energy from sunlight, produce ATP and NADPH.

• Calvin cycle: Uses ATP and NADPH to fix carbon dioxide into glucose.

Equation for photosynthesis: $6\text{CO}_2 + 6\text{H}_2\text{O} + \text{light energy} \rightarrow \text{C}_6\text{H}_{12}\text{O}_6 + 6\text{O}_2$

Ch. 11: Cell Communication

Signaling Mechanisms

Cells communicate through chemical signals, which are received and processed by target cells.

• Signal transduction pathways: Convert signals into cellular responses.

• Types of signaling: Autocrine, paracrine, endocrine, and direct contact.

Second messengers (e.g., cAMP, Ca2+) amplify signals inside cells.

Ch. 12: The Cell Cycle

Cell Division

The cell cycle consists of interphase (growth and DNA replication) and mitotic phase (division).

• Mitosis: Produces two genetically identical daughter cells.

• Cytokinesis: Division of cytoplasm.

Checkpoints regulate progression through the cell cycle.

Ch. 13: Meiosis and Sexual Life Cycles

Genetic Variation

Meiosis produces gametes (sperm and egg) with half the chromosome number, increasing genetic diversity.

• Meiosis I: Homologous chromosomes separate.

• Meiosis II: Sister chromatids separate.

• Crossing over: Exchange of genetic material between homologous chromosomes.

Ch. 14: Mendel and the Gene Idea

Principles of Inheritance

Gregor Mendel discovered the basic principles of heredity using pea plants.

• Law of Segregation: Each organism carries two alleles for each gene, which separate during gamete formation.

• Law of Independent Assortment: Genes for different traits assort independently during gamete formation.

Mendelian ratio for monohybrid cross: $3:1$

Ch. 15: The Chromosomal Basis of Inheritance

Chromosomes and Genes

Genes are located on chromosomes, which undergo segregation and independent assortment.

• Sex-linked traits: Genes located on sex chromosomes (X and Y).

• Chromosomal abnormalities: Include nondisjunction, deletions, duplications.

Ch. 16: The Molecular Basis of Inheritance

DNA Structure and Replication

DNA is a double helix composed of nucleotides (adenine, thymine, cytosine, guanine).

• Replication: DNA is copied before cell division by DNA polymerase.

• Base pairing: A-T and G-C via hydrogen bonds.

Chargaff's rule: $\%A = \%T, \%G = \%C$

Ch. 17: Gene Expression: From Gene to Protein

Transcription and Translation

Gene expression involves transcription (DNA to RNA) and translation (RNA to protein).

• Transcription: RNA polymerase synthesizes mRNA from DNA template.

• Translation: Ribosomes synthesize proteins using mRNA, tRNA, and rRNA.

Central Dogma: $\text{DNA} \rightarrow \text{RNA} \rightarrow \text{Protein}$

Ch. 19: Viruses

Viral Structure and Life Cycles

Viruses are nonliving infectious agents composed of nucleic acid and protein coat.

• Lytic cycle: Virus replicates and destroys host cell.

• Lysogenic cycle: Viral DNA integrates into host genome.