Ap Bio Review

I. Chemistry of Life

1. Water

   • Polarity: allows for hydrogen bonding

   • Cohesion: water molecules stick together

   • Adhesion: water molecules stick to other substances

   • High specific heat: moderates temperature

   • Solvent: dissolves polar substances

2. Carbon

   • Forms diverse molecules due to its ability to bond with four other atoms

   • Hydrocarbons: organic molecules consisting of only carbon and hydrogen

3. Macromolecules

   • Polymers: long molecules consisting of many similar or identical building blocks (monomers)

   • Carbohydrates: sugars and polymers of sugars

     • Monosaccharides: simple sugars (e.g., glucose, fructose)

     • Polysaccharides: polymers of monosaccharides (e.g., starch, cellulose)

   • Lipids: fats, phospholipids, and steroids

     • Fats: glycerol + fatty acids (saturated vs. unsaturated)

     • Phospholipids: major component of cell membranes (hydrophilic head, hydrophobic tail)

     • Steroids: lipids characterized by a carbon skeleton consisting of four fused rings (e.g., cholesterol)

   • Proteins: polymers of amino acids

     • Amino acids: organic molecules with carboxyl and amino groups

     • Polypeptides: polymers of amino acids

     • Four levels of protein structure: primary, secondary, tertiary, quaternary

   • Nucleic Acids: polymers of nucleotides (DNA and RNA)

     • Nucleotides: consist of a nitrogenous base, a pentose sugar, and a phosphate group

4. Enzymes

   • Biological catalysts that speed up chemical reactions by lowering activation energy

   • Substrate-specific

   • Activity affected by temperature, pH, and inhibitors (competitive vs. noncompetitive)

II. The Cell

1. Cell Structure

   • Prokaryotic vs. Eukaryotic Cells

     • Prokaryotic: No nucleus, bacteria and archaea

     • Eukaryotic: Nucleus and membrane-bound organelles

   • Organelles:

     • Nucleus: contains DNA

     • Ribosomes: synthesize proteins

     • Endoplasmic Reticulum (ER):

       • Rough ER: ribosomes attached, protein synthesis

       • Smooth ER: lipid synthesis, detoxification

     • Golgi Apparatus: modifies and packages proteins

     • Lysosomes: intracellular digestion

     • Mitochondria: cellular respiration

     • Chloroplasts (in plants): photosynthesis

     • Cell Membrane: phospholipid bilayer with embedded proteins

2. Cell Transport

   • Passive Transport: no energy required (diffusion, osmosis, facilitated diffusion)

   • Active Transport: requires energy (ATP) to move substances against their concentration gradients

   • Bulk Transport: endocytosis (phagocytosis, pinocytosis) and exocytosis

3. Cell Communication

   • Cell signaling: reception, transduction, response

   • Types of signaling: paracrine, endocrine, synaptic

   • Signal transduction pathways: convert signals into cellular responses

III. Cellular Energetics

1. Metabolism

   • Catabolism: breaking down molecules

   • Anabolism: building molecules

2. Photosynthesis

   • Light-dependent reactions: convert light energy into chemical energy (ATP and NADPH)

   • Calvin cycle: uses ATP and NADPH to convert $CO_2$ to sugar

3. Cellular Respiration

   • Glycolysis: breaks down glucose into pyruvate

   • Krebs Cycle (Citric Acid Cycle)

     • Pyruvate is oxidized and enters the Krebs Cycle, producing ATP, NADH, and FADH2

   • Electron Transport Chain (ETC)

     • NADH and FADH2 deliver electrons to the ETC, powering ATP synthesis through oxidative phosphorylation

IV. Cell Communication and Cell Cycle

1. Cell Communication

   • Signaling molecules: Ligands bind to receptors

   • Signal transduction: Amplification and conversion of signals

   • Cellular responses: Changes in gene expression or protein activity

2. Cell Cycle

   • Interphase: Cell growth and DNA replication (G1, S, G2 phases)

   • Mitosis: Nuclear division (prophase, metaphase, anaphase, telophase)

   • Cytokinesis: Cytoplasmic division

   • Regulation: Checkpoints (G1, G2, M) ensure proper cell division; controlled by cyclins and cyclin-dependent kinases (Cdks)

V. Heredity

1. Meiosis and Genetic Variation

   • Meiosis: Reduces chromosome number (2n to n) for sexual reproduction

   • Genetic variation: Arises from crossing over, independent assortment, and random fertilization

2. Mendelian Genetics

   • Laws of inheritance: Segregation and independent assortment

   • Monohybrid and dihybrid crosses: Predicting genotypes and phenotypes

   • Non-Mendelian genetics: Incomplete dominance, codominance, multiple alleles, sex-linked traits

3. Chromosomal Inheritance

   • Linked genes: Genes located near each other on the same chromosome tend to be inherited together

   • Chromosomal abnormalities: Nondisjunction, deletions, duplications, inversions, translocations

VI. Gene Expression and Regulation

1. DNA Structure and Replication

   • DNA structure: Double helix with complementary base pairing (A-T, C-G)

   • DNA replication: Semiconservative replication with leading and lagging strands

2. Transcription and Translation

   • Transcription: DNA to RNA (mRNA, tRNA, rRNA)

   • Translation: RNA to protein at ribosomes

   • Genetic code: Codons specify amino acids

3. Gene Regulation

   • Prokaryotic gene regulation: Operons (e.g., lac operon)

   • Eukaryotic gene regulation: Transcription factors, enhancers, silencers

   • Epigenetics: Modifications to DNA and histones that affect gene expression

VII. Natural Selection

1. Evolution

   • Evidence for evolution: Fossil record, comparative anatomy, biogeography, molecular biology

   • Mechanisms of evolution: Natural selection, genetic drift, gene flow, mutation

2. Natural Selection

   • Variation: Individuals in a population vary in their traits

   • Inheritance: Traits are heritable

   • Differential survival and reproduction: Individuals with advantageous traits are more likely to survive and reproduce

   • Adaptation: Accumulation of favorable traits in a population over time

3. Speciation

   • Reproductive isolation: Prezygotic and postzygotic barriers

   • Modes of speciation: Allopatric and