ap bio midterm study set

Four Properties of Water

1) Cohesion: water molecules stick together via hydrogen bonds; helps transport in plants. 2) Adhesion: water sticks to other surfaces; aids capillary action. 3) High specific heat: resists temperature change; stabilizes climate and body temp. 4) Universal solvent: dissolves polar molecules; supports biochemical reactions. Structure: water is polar, forms hydrogen bonds. Hint: CHSU = Cohesion, Heat, Solvent, Universal.

Examples of Macromolecules

Carbs: glucose, starch (-ose suffix). Lipids: fats, oils. Proteins: enzymes (-ase suffix). Nucleic acids: DNA, RNA.

Atoms in Each Macromolecule

Carbs: C,H,O (1:2:1 ratio). Lipids: mostly C,H (few O). Proteins: C,H,O,N,S. Nucleic acids: C,H,O,N,P.

Monomers of Macromolecules

Carbs: monosaccharides. Proteins: amino acids. Nucleic acids: nucleotides. Lipids: not true polymers (fatty acids + glycerol).

Functions of Macromolecules

Carbs: energy storage, structure (cell walls). Lipids: long-term energy, membranes, signaling. Proteins: enzymes, transport, defense, structure. Nucleic acids: genetic info, protein synthesis.

Classes of Proteins

Enzymes (catalysis), Structural (keratin), Transport (hemoglobin), Defensive (antibodies), Regulatory (hormones).

Levels of Protein Structure

Primary: amino acid sequence (peptide bonds). Secondary: alpha helices/beta sheets (H-bonds). Tertiary: 3D folding (hydrogen, ionic, hydrophobic, covalent, vanderwaal). Quaternary: multiple polypeptides (same bonds as tertiary).

Three Subgroups of Amino Acids

Polar, nonpolar, charged (acidic/basic).

Regulatory Binding Sites

Allosteric sites; binding can activate or inhibit enzyme.

Protein Denaturation

Caused by heat, pH, salinity; protein loses shape and function.

Autotroph vs Heterotroph Nutrient Sources

Autotrophs: CO2, minerals; Heterotrophs: organic molecules. Adaptations: roots, leaves, digestive systems.

Purpose of Control Group

Provides baseline for comparison; isolates effect of independent variable.

Null vs Alternate Hypothesis

Null: no effect; Alternate: effect exists.

Rate Calculation

Slope of graph (Δy/Δx) when time is on X-axis.

SEM

Standard Error of Mean; mean ± 2 SEM shows confidence interval. Overlap = no significant difference.

Surface Area / Volume Ratio

Surface area allows exchange of materials; volume represents metabolic needs. Cells optimize ratio by being small and having organelles with folds (microvilli, cristae). Hint: High SA/V = efficient exchange.

SA/V in Multicellular Organisms

Plants: root hairs increase absorption. Animals: alveoli in lungs maximize gas exchange. Both increase surface area relative to volume.

Three Structures in All Cells

Plasma membrane (selective barrier), DNA (genetic info), Ribosomes (protein synthesis).

Differentiate Prokaryotic vs Eukaryotic Cells

Prokaryotes: no nucleus, no membrane-bound organelles, smaller size. Eukaryotes: nucleus, organelles, larger size.

Differentiate Plant vs Animal Cells

Plant: cell wall, chloroplasts. Animal: no cell wall, has centrioles.

Purpose of Organelles

Compartmentalization allows specialized functions and efficiency. Membranes isolate reactions.

Endosymbiosis

Theory: mitochondria and chloroplasts originated from engulfed prokaryotes. Evidence: double membranes, own DNA, ribosomes, replicate independently.

Protein Journey for Secretion

DNA transcribed to mRNA in nucleus → translation on rough ER → folding and modification → Golgi for packaging → vesicle transport → exocytosis.

Protein Journey for Cytoplasmic Use

Synthesized on free ribosomes → stays in cytoplasm (no ER/Golgi processing).

Selective Permeability Components

Phospholipid bilayer blocks polar molecules; membrane proteins select and transport specific substances.

Structure and Function of Cell Membrane Components

Bilayer: hydrophobic tails prevent polar molecules crossing. Proteins: channels/carriers allow selective passage.

Sample Particles Crossing Membrane

Small nonpolar: diffuse freely. Ions: facilitated diffusion via channels. Large molecules: active transport or endocytosis.

Purpose of Co-Transport

Moves molecules against gradient using energy from another molecule’s gradient. Powered by proton or ion gradients set up by pumps.

Other Membrane Components

Cholesterol (fluidity), glycoproteins/glycolipids (cell recognition), integral proteins (transport), peripheral proteins (signaling).

Osmosis Scenario: 0.8 M Outside vs 0.0 M Inside

Outside is hypertonic; water moves out of cell.

Osmosis Scenario: 0.4 M Outside vs 0.4 M Inside

Outside is isotonic; no net water movement.

Two Laws of Thermodynamics

1) Energy cannot be created or destroyed, only transformed. 2) Every energy transfer increases entropy (disorder).

Helping Nonspontaneous Reactions

Cells couple reactions to ATP hydrolysis; lowers overall free energy. Hint: "Coupling = make it go."

Speeding Up Slow Reactions

Use enzymes to lower activation energy; reaction rate increases without changing ΔG.

ATP Components

Adenine, ribose, three phosphate groups. High energy due to repulsion between negative phosphate groups.

Why ATP is Unstable

Three phosphates repel each other; bonds store potential energy.

Processes Using ATP

Active transport, muscle contraction, protein synthesis, cell signaling.

Enzyme Regulation

Often turned off by allosteric inhibitors or feedback inhibition; inhibitor binds enzyme and changes shape.

Cellular Respiration Equation

C6H12O6 + 6O2 → 6CO2 + 6H2O + ATP. Main product: ATP. [Diagram: Cellular Respiration Stages]

Stages of Cellular Respiration

Glycolysis (cytoplasm), Citric Acid Cycle (mitochondrial matrix), Electron Transport Chain (inner mitochondrial membrane). In prokaryotes: cytoplasm and plasma membrane.

Inputs and Outputs of Glycolysis

Input: glucose, NAD+, ADP. Output: pyruvate, NADH, ATP.

Inputs and Outputs of Citric Acid Cycle

Input: acetyl-CoA, NAD+, FAD, ADP. Output: CO2, NADH, FADH2, ATP.

Inputs and Outputs of Electron Transport Chain

Input: NADH, FADH2, O2. Output: ATP, H2O.

Oxidative Phosphorylation Steps

1) Electron transport pumps H+ to create gradient. 2) ATP synthase uses gradient to make ATP.

Role of Oxygen in Respiration

Final electron acceptor in ETC; forms water.

Fermentation Purpose

Regenerates NAD+ for glycolysis; produces small ATP without oxygen. Unsustainable because low ATP yield and lactic acid buildup.

Photosynthesis Equation

6CO2 + 6H2O + light → C6H12O6 + 6O2. Main product: glucose. [Diagram: Photosynthesis Light and Dark Reactions]

Light Reactions Products

ATP, NADPH, O2. Location: thylakoid membranes (eukaryotes), plasma membrane (prokaryotes).

Initial Step of Light Reactions

Light excites electrons in chlorophyll; energy passed to ETC.

Role of Water in Light Reactions

Split to provide electrons; releases O2 as byproduct.

Calvin Cycle Location

Stroma (eukaryotes), cytoplasm (prokaryotes).

Three Purposes for Energy Use

Growth, reproduction, maintenance. Conservation strategies: hibernation, migration, torpor.

Extra Energy Use

Stored as fat or glycogen.

Endothermy Advantage

Stable internal temperature; supports high activity. Challenge: high energy cost.

Temperature Regulation

Ectotherms: basking, burrowing. Endotherms: shivering, sweating, fur insulation.

How Cells Receive Environmental Signals

Receptors on cell membrane or inside cell bind ligands (signal molecules). Types: membrane-bound receptors for hydrophilic ligands; intracellular receptors for hydrophobic ligands.

Triggering a Signaling Cascade

Ligand binding changes receptor shape → activates intracellular signaling proteins → second messengers amplify signal → cascade leads to response.

Ways the “Next” Part is Activated

Phosphorylation by kinases, second messengers (cAMP, Ca2+), conformational changes in proteins.

Two Ways Cells Change Activity

1) Gene expression changes (turn genes on/off). Example: steroid hormones activating transcription. 2) Enzyme activity changes (activate/inhibit metabolic pathways). Example: insulin signaling increases glucose uptake.

Direct Cell-to-Cell Contact Example

Gap junctions in animal cells; plasmodesmata in plant cells.

Short-Distance Signaling Example

Paracrine signaling: neurotransmitters between neurons; local growth factors.

Long-Distance Signaling Example

Endocrine signaling: hormones travel via bloodstream (e.g., insulin).

Insulin Targets and Effect

Targets liver, muscle, fat cells; increases glucose uptake and glycogen synthesis.

Negative vs Positive Feedback

Negative: response reduces stimulus (homeostasis). Positive: response amplifies stimulus (childbirth contractions). Biological systems mostly use negative feedback.

Day/Night Internal Clock

Circadian rhythm (~24 hours). Responses: sleep cycles, leaf opening/closing.

Seasonal Internal Clock

Photoperiodism. Responses: flowering in plants, migration in animals.

Purposes of Mitotic Cell Division

Growth, repair, asexual reproduction.

Mitosis vs Binary Fission

Mitosis: eukaryotic cells, involves nucleus and spindle fibers. Binary fission: prokaryotes, simpler process without nucleus.

Stages of Cell Cycle

Interphase (G1 growth, S DNA replication, G2 prep), Mitosis (PMAT), Cytokinesis. [Diagram: Cell Cycle]

Concept of Checkpoints

Control points ensure proper division; proteins like cyclins and CDKs regulate progression past checkpoints.