Ch. 1 – Evolution, the Themes of Biology, and Scientific Inquiry

Characteristics of Living Things

• Order: Living organisms exhibit complex but ordered organization.

• Regulation (Homeostasis): Ability to maintain stable internal conditions.

• Growth and Development: Organisms increase in size and complexity, following specific instructions coded in their DNA.

• Energy Processing: Use of energy to power activities and chemical reactions.

• Response to Environment: Ability to sense and react to stimuli.

• Reproduction: Production of offspring, passing genetic material to the next generation.

• Evolutionary Adaptation: Populations change over generations through adaptations that enhance survival and reproduction.

Levels of Biological Organization

• Biosphere (all life on Earth) → Ecosystems → Communities → Populations → Organisms → Organs/Organ Systems → Tissues → Cells → Organelles → Molecules

• Example: A leaf (organ) contains tissues, which are made of cells, which contain organelles, composed of molecules.

Controlled Experiments

• Definition: An experiment in which only one variable is changed at a time, while all others are kept constant.

• Purpose: To determine the effect of the independent variable on the dependent variable.

Hypothesis vs. Theory

• Hypothesis: A testable, tentative explanation for an observation.

• Theory: A broad, well-supported explanation for a wide range of phenomena, supported by extensive evidence.

• Example: "All living things are made of cells" is a theory; "If plants are given fertilizer, they will grow taller" is a hypothesis.

Ch. 2 – The Chemical Context of Life

Chemical Bonds Important to Biology

• Covalent Bonds: Atoms share electrons; strong and stable (e.g., H2O).

• Ionic Bonds: Transfer of electrons from one atom to another, forming charged ions (e.g., NaCl).

• Hydrogen Bonds: Weak attractions between a hydrogen atom and an electronegative atom (e.g., between water molecules).

• Van der Waals Interactions: Weak, transient attractions between molecules or parts of molecules.

Ch. 3 – Water and Life

Characteristics of Water

• Cohesion: Water molecules stick together via hydrogen bonds.

• Adhesion: Water molecules stick to other substances.

• High Specific Heat: Water resists temperature changes.

• Universal Solvent: Many substances dissolve in water due to its polarity.

• Ice Floats: Solid water is less dense than liquid water.

Moles and Molarity

• Mole: Amount of substance containing Avogadro's number () of particles.

• Molarity (M): Moles of solute per liter of solution.

Formula:

Hydrophobic vs. Hydrophilic Substances

• Hydrophobic: Repel water; nonpolar (e.g., oils).

• Hydrophilic: Attract water; polar or charged (e.g., salts, sugars).

Ch. 4 – Carbon and the Molecular Diversity of Life

Characteristics of Organic Molecules

• Contain carbon atoms bonded to hydrogen, oxygen, nitrogen, and other elements.

• Form the backbone of biological macromolecules.

Types of Isomers

• Structural Isomers: Differ in covalent arrangement of atoms.

• Cis-Trans (Geometric) Isomers: Differ in spatial arrangement around double bonds.

• Enantiomers: Mirror images of each other; differ in arrangement around an asymmetric carbon.

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

Functions of Biomolecules

• Carbohydrates: Energy storage and structural support.

• Lipids: Long-term energy storage, membrane structure, signaling.

• Proteins: Enzymes, structure, transport, signaling, defense.

• Nucleic Acids: Store and transmit genetic information (DNA, RNA).

Polymerization

• Process of linking monomers to form polymers via dehydration reactions (removal of water).

Classification of Sugars

• By carbon number (triose, pentose, hexose).

• By functional group (aldose or ketose).

Levels of Protein Structure

• Primary: Sequence of amino acids (peptide bonds).

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

• Tertiary: 3D folding (hydrophobic interactions, disulfide bridges, ionic bonds).

• Quaternary: Association of multiple polypeptides.

Ch. 6 – A Tour of the Cell

Limits to Cell Size

• Surface area-to-volume ratio limits cell size; efficient exchange of materials requires a high ratio.

Function of Cellular Structures

• Nucleus: Stores genetic material.

• Mitochondria: Site of cellular respiration.

• Chloroplasts: Site of photosynthesis (plants/algae).

• Endoplasmic Reticulum: Protein and lipid synthesis.

• Golgi Apparatus: Modifies, sorts, and packages proteins/lipids.

• Lysosomes: Digestion of macromolecules.

Cytoskeleton Composition

• Microtubules: Hollow tubes; cell shape, chromosome movement.

• Microfilaments: Actin filaments; cell movement, muscle contraction.

• Intermediate Filaments: Structural support.

Ch. 7 – Membrane Structure and Function

Passive Transport

• Simple Diffusion: Movement of small, nonpolar molecules down their concentration gradient.

• Facilitated Diffusion: Movement via transport proteins (channels/carriers) for ions and polar molecules.

• Osmosis: Diffusion of water across a selectively permeable membrane.

Active Transport

• Movement of substances against their concentration gradient, requiring energy (usually ATP).

• Example: Sodium-potassium pump.

Membrane Permeability

• Small, nonpolar molecules (O2, CO2) move easily.

• Ions and large polar molecules require transport proteins.

Ch. 8 – An Introduction to Metabolism

Exergonic vs. Endergonic Reactions

• Exergonic: Release energy; spontaneous (e.g., cellular respiration).

• Endergonic: Require energy input; non-spontaneous (e.g., photosynthesis).

Potential vs. Kinetic Energy

• Potential Energy: Stored energy (e.g., chemical bonds).

• Kinetic Energy: Energy of motion (e.g., movement of molecules).

Activation Energy and Enzymes

• Activation Energy (Ea): Energy required to start a reaction.

• Enzymes: Lower activation energy, speeding up reactions.

Ch. 9 – Cellular Respiration and Fermentation

Catabolism vs. Anabolism

• Catabolism: Breakdown of molecules to release energy.

• Anabolism: Synthesis of complex molecules from simpler ones; requires energy.

Fermentation

• Anaerobic process; regenerates NAD+ by converting pyruvate to lactic acid or ethanol.

Glycolysis

• First step of cellular respiration; breaks glucose into two pyruvate molecules, producing ATP and NADH.

Ch. 10 – Photosynthesis

PURPOSE OF PHOTOSYNTHESIS

• Convert light energy into chemical energy (glucose) in plants, algae, and some bacteria.

Light and Dark Reactions

• Light Reactions: Occur in thylakoid membranes; produce ATP and NADPH, release O2.

• Calvin Cycle (Dark Reactions): Occur in stroma; use ATP and NADPH to fix CO2 into glucose.

Ch. 11 – Cell Communication

Location of Receptor Proteins

• Receptors can be located in the plasma membrane (for hydrophilic ligands) or inside the cell (for hydrophobic ligands).

Ch. 12 – The Cell Cycle

Stages of Mitosis

• Prophase: Chromosomes condense, spindle forms.

• Metaphase: Chromosomes align at the metaphase plate.

• Anaphase: Sister chromatids separate to opposite poles.

• Telophase: Nuclear envelopes reform, chromosomes decondense.

Ch. 13 – Meiosis and Sexual Life Cycles

Purpose of Cellular Division

• Growth, repair, and reproduction.

Haploid vs. Diploid Cells

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

• Diploid (2n): Two sets of chromosomes (e.g., somatic cells).

Ch. 14 – Mendel and the Gene Idea

Punnett Squares

• Tool to predict the probability of offspring genotypes and phenotypes from parental crosses.

Phenotypic and Genotypic Ratios

• Phenotypic Ratio: Ratio of observable traits in offspring.

• Genotypic Ratio: Ratio of genetic combinations in offspring.

• Example: Monohybrid cross (Aa x Aa): Genotypic ratio 1:2:1 (AA:Aa:aa), Phenotypic ratio 3:1 (dominant:recessive).

Ch. 16 – The Molecular Basis of Inheritance

DNA Replication

• Semiconservative process; each new DNA molecule has one old and one new strand.

Structure of DNA

• Double helix; sugar-phosphate backbone; complementary base pairing (A-T, G-C).

Enzymes in DNA Replication

• Helicase: Unwinds DNA.

• Primase: Synthesizes RNA primer.

• DNA Polymerase: Adds nucleotides to new strand.

• Ligase: Joins Okazaki fragments.

Ch. 17 – Gene Expression: From Gene to Protein

Codons and Anticodons

• Codon: Three-nucleotide sequence on mRNA that codes for an amino acid.

• Anticodon: Three-nucleotide sequence on tRNA complementary to the mRNA codon.

Ch. 18 – Regulation of Gene Expression

Function of Operons

• Clusters of genes under control of a single promoter; allow coordinated regulation in prokaryotes.

Tryptophan Operon

• Repressible operon; turned off when tryptophan is present.

Ch. 19 – Viruses

Lytic vs. Lysogenic Cycles

• Lytic: Virus replicates rapidly, destroys host cell.

• Lysogenic: Viral DNA integrates into host genome, replicates with cell, can later enter lytic cycle.