Focus: Cellular energetics, including cellular respiration and photosynthesis.
Topics covered: Enzymes, cellular energy & ATP, photosynthesis (light reactions & Calvin cycle), and cellular respiration (glycolysis, link reaction, Krebs cycle, electron transport chain).
Presenter: Glenn Wokenfeld (Mr. W), retired AP Biology teacher.
Resources: Checklist at AP bios.c/checklist, Learn-Biology.com AP Bio curriculum, BiomMania AP Bio app.
Enzymes (Topics 3.1 to 3.3)
Properties of Enzymes
Nature: Most enzymes are proteins, some are RNA.
Function: Catalyze reactions by lowering activation energy.
Specificity: Highly specific, with active sites complementary to substrates.
Structure: Composed of secondary, tertiary, and quaternary structures with hydrogen/ionic bonds.
Environmental Impact: Denatured by changes in pH, temperature, or ion concentration.
Enzyme Activity
pH Changes: Most enzymes have an optimal pH; performance drops outside this range due to bond disruption.
Temperature Changes: Activity increases with temperature until a peak, beyond which denaturation occurs.
Substrate Concentration: Increases reaction rate until saturation point is reached.
Inhibition
Competitive Inhibition: Molecule competes with substrate for active site.
Non-competitive Inhibition: Molecule binds to allosteric site, altering active site shape.
Cellular Energy (Topic 3.4)
Metabolic Pathways
Definition: Series of enzyme-catalyzed reactions.
Types: Linear (e.g., glycolysis) and cyclical (e.g., Krebs and Calvin cycles).
Autotrophs vs. Heterotrophs
Autotrophs: Produce their own food (e.g., plants via photosynthesis, some bacteria via chemosynthesis).
Heterotrophs: Obtain energy from organic compounds produced by other organisms.
Exergonic vs. Endergonic Reactions
Exergonic: Releases energy (e.g., cellular respiration).
Endergonic: Requires energy input (e.g., photosynthesis).
ATP
Structure: Ribose sugar, adenine, three phosphates.
Function: Powers cellular work; ATP synthesis and breakdown store/release energy.
Photosynthesis
Overview
Process: Converts light energy into chemical energy (glucose) using CO2 and H2O.
Equation: 6 CO2 + 6 H2O + light energy → C6H12O6 + 6 O2
Type: Endergonic reaction.
Evolution and Consequences
Evolution: Evolved ~3.5 billion years ago.
Consequences: Produced oxygen-rich atmosphere, enabled aerobic metabolism and life on land.
Phases of Photosynthesis
Light Reactions: Occur in thylakoid membranes, produce ATP and NADPH through photoexcitation and electron transport.
Calvin Cycle: Occurs in stroma, fixes CO2 into carbohydrates using ATP and NADPH.
Cellular Respiration
Overview
Process: Converts glucose and oxygen into ATP, CO2, and water.
Equation: C6H12O6 + 6 O2 → 6 CO2 + 6 H2O + ATP
Type: Exergonic reaction.
Phases
Glycolysis: Occurs in cytoplasm, anaerobic, yields pyruvate, ATP, and NADH.
Link Reaction: Converts pyruvate to acetyl CoA, produces NADH and CO2.
Krebs Cycle: Occurs in mitochondrial matrix, produces ATP, NADH, FADH2, and CO2.
Electron Transport Chain: Occurs in mitochondrial membrane, uses NADH/FADH2 to produce ATP.
Anaerobic Respiration and Fermentation
Difference: Aerobic uses oxygen and produces more ATP; anaerobic occurs without oxygen, limited ATP (2 per glucose).
Fermentation Types: Alcohol (yeast) and lactic acid (muscle tissue), regenerate NAD+ for glycolysis continuity.
Conclusion
Utilize resources like learn-biology.com for better comprehension and preparation for exams.
Next steps include studying Unit 4 on cell communication, division, and feedback mechanisms.