AP_Bio_Cram_Chart_2021

Chemistry of Life

• Water Properties

  • Has hydrogen bonds, allowing for special properties such as:

    • Cohesion: Water molecules stick together.

    • Adhesion: Water molecules stick to other surfaces.

    • Surface Tension: Water’s cohesive properties create a tension at its surface.

• Biological Macromolecules

  • Monomers & Polymers:

    • Monomers (single units) form polymers through dehydration synthesis.

    • Hydrolysis breaks down polymers into monomers.

  • Nucleic Acids:

    • Composed of nucleotides (deoxy/ribose, phosphate, nitrogen base).

    • Includes DNA and RNA, crucial for storing genetic information.

  • Proteins:

    • Made of amino acids; the sequence of polypeptides determines structure and function.

  • Carbohydrates:

    • Formed from sugar monomers.

  • Lipids:

    • Nonpolar, variations in saturation affect structure/function; major component of cell membranes.

• Cellular Components

  • Ribosomes found in all life forms, responsible for protein synthesis.

  • Mitochondria: Site of cellular respiration.

  • Chloroplasts: Contain thylakoids and stroma; convert light into energy.

  • Cell Size: Surface area-to-volume ratio critical for material exchange; larger SA with smaller volume is ideal.

  • Phospholipid Bilayers: Semipermeable membranes that require channel proteins for specific nutrient transport.

    • Passive Transport: Movement along the concentration gradient (high to low).

    • Active Transport: Movement against the gradient (low to high).

  • Organisms like plants, fungi, and prokaryotes have cell walls for permeability and structural support.

• Enzyme Function

  • Enzymes lower activation energy to catalyze reactions.

  • Inhibition:

    • Competitive Inhibitors: Bind to active sites.

    • Noncompetitive Inhibitors: Bind to allosteric sites altering enzyme shape.

  • Optimal conditions for enzymes include specific pH, temperature, and substrate concentration before denaturing.

Photosynthesis & Cellular Respiration

• Photosynthesis:

  • Two parts:

    • Light-dependent reactions charge electrons in photosystems I & II.

    • Calvin cycle produces carbohydrates.

• Cellular Respiration:

  • Produces ATP; fermentation occurs sans oxygen.

  • Electron transfers create a proton gradient, storing energy in ATP for cellular functions.

Cell Communication & Cell Cycle

• Signaling Types:

  • Paracrine Signaling: Local signaling using signaling molecules.

  • Endocrine Signaling: Long-distance signaling.

• Signal Transduction Pathways:

  • Three stages:

    • Reception: Ligand binds to cell membrane receptors (e.g., ion-gated or G-protein coupled).

    • Transduction: Signal is amplified and converted into a recognizable form for the cell.

    • Response: Triggers gene transcription or other cellular responses.

• Feedback Mechanisms:

  • Negative Feedback: Reduces stimulus (e.g., insulin/glucose regulation).

  • Positive Feedback: Enhances responses (e.g., oxytocin in childbirth).

• Cell Cycle:

  • Interphase includes G1, S, and G2 stages, followed by mitosis, which produces identical daughter cells.

  • Checkpoints exist at G1, G2-M transitions, and metaphase to prevent cell abnormalities.

Meiosis & Genetics

• Meiosis:

  • Two parts to form haploid cells; homologous chromosomes separate.

  • Crossing over increases genetic diversity.

• Mendelian Genetics:

  • Predicts outcomes of single-gene traits but some traits do not follow these laws, complicating predictions.

• Genetic Diversity Sources:

  • Crossing over in prophase I, independent assortment during metaphase I (2^23 combinations in humans), random fertilization.

• Genetic Disorders:

  • Result from allele mutations or sequence changes (nondisjunction).

• DNA & RNA:

  • Store genetic material. Prokaryotic chromosomes are circular; eukaryotic chromosomes are linear.

  • Bases include purines (G, A) and pyrimidines (C, T, U).

• DNA Replication:

  • Occurs from 5' to 3'; semi-conservative.

  • Helicase unwinds DNA; topoisomerase prevents coiling; RNA primers assist DNA polymerase in synthesis.

  • Ligase connects fragments in the lagging strand.

• Transcription & Translation:

  • Transcription copies DNA to RNA; post-transcription modifications include adding a GTP cap, a poly-A tail, and intron removal.

  • Translation involves ribosomes reading mRNA and tRNA matching amino acids to codons.

• Mutations:

  • Can alter protein functions; may lead to loss, gain, or no change in functions.

• DNA Techniques:

  • Gel electrophoresis separates DNA by size, PCR amplifies DNA, sequencing identifies nucleotide order.

  • Bacterial transformation introduces DNA to bacteria.

Evolution & Ecology

• Evolutionary Fitness:

  • Measured by reproductive success; competition drives natural selection.

• Selective Pressures:

  • Environmental changes create pressures that affect phenotypes.

• Random Events:

  • Mutations and genetic drift also drive evolution.

• Hardy-Weinberg Equation:

  • Predicts genetic equilibrium frequencies.

• Dating Fossils:

  • Methods include carbon-14 dating and examining surrounding rock ages.

• Common Ancestry:

  • Explains relationships; phylogenetic trees and cladograms illustrate these links.

• Extinction and Biodiversity:

  • Extinction creates niches; more biodiversity means greater ecosystem resilience.

Population Dynamics

• Homeostasis:

  • Maintenance of internal equilibrium in response to external changes.

• Energy and Growth:

  • Net energy gain is necessary for organism growth.

• Endothermic vs. Exothermic:

  • Endotherms use thermal energy to regulate temperature; exotherms do not.

• Population Limits:

  • Factors include size, changes over time, and carrying capacity, often represented by an s-curve.

• Simpson's Diversity Index:

  • Measures ecosystem diversity; higher biodiversity increases resilience.

• Species Interactions:

  • Includes commensalism, mutualism, parasitism, predator-prey, and competition.

• Energy Transfer:

  • Only 10% of energy passes between trophic levels; most is lost as heat.

FRQ Tips

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