Enzyme Structure and Function (3.1 & 3.2)

Enzyme Structure and Function (3.1 & 3.2)

• Enzymes are biological catalysts that speed up chemical reactions in cells.
• Enzymes have an active site, a specific region for interacting with substrate molecules.
• Substrate shape and charge must match the active site for enzyme activity.
• Enzymes lower activation energy, the energy needed for a reaction to begin.
• Enzyme structure affects their function; changes can alter/disable catalytic capabilities.

Environmental Impacts on Enzyme Function (3.3)

• Denaturation occurs when proteins lose their three-dimensional structure, halting enzyme function.
• Environmental pH and temperature outside optimal ranges can denature enzymes, affecting reaction efficiency.
• Denaturation can sometimes be reversible.
• Enzyme activity is affected by environmental pH, disrupting hydrogen bonds vital to enzyme structure.
• Substrate and product concentration impact reaction efficiency.
• Higher temperatures increase molecule movement, increasing collisions between enzymes and substrates, and reaction rate.
• Competitive inhibitors reversibly or irreversibly bind to the active site, blocking substrate access.
• Noncompetitive inhibitors bind at allosteric sites, altering enzyme activity.

Cellular Energy (3.4)

• Living systems need a constant energy input to maintain order and drive cellular processes.
• Energy input must surpass energy loss to sustain order.
• Energy-releasing and energy-requiring processes can be coupled.
• Metabolic pathways are sequential, controlling and improving energy transfer.

Photosynthesis (3.5)

• Photosynthesis captures solar energy and converts it into stored chemical energy (sugars).
• Photosynthesis originated in prokaryotes.
• Photosynthesis in cyanobacteria led to an oxygenated atmosphere.
• Prokaryotic pathways were foundational to eukaryotic photosynthesis.
• Light-dependent reactions use light energy to generate ATP and NADPH, used by the Calvin Cycle.
• Photosystems contain chlorophyll that absorbs light energy, boosting electrons.
• Light-dependent reactions occur in the thylakoid membranes of chloroplasts.
• Electron transport chains (ETC) transfer energized electrons via a series of reactions, creating a proton electrochemical gradient.
• Electrochemical gradient drives ATP synthesis using ATP synthase.

Cellular Respiration (3.6)

• Cellular respiration and fermentation utilize energy from biological molecules to produce ATP.
• Eukaryotic respiration involves a series of enzyme-catalyzed reactions.
• Electron transport chain reactions occur in chloroplasts, mitochondria, and prokaryotic cell membranes.
• Electrons are passed down an ETC to oxygen, the terminal electron acceptor during aerobic respiration.
• In respiration, NADH and FADH2 deliver electrons to the ETC.
• Proton gradient across membranes drives ATP synthesis via chemiosmosis.
• Oxidative phosphorylation generates ATP in cellular respiration (like photophosphorylation in photosynthesis).
• Decoupling can generate heat to regulate body temperature.
• Glycolysis breaks down glucose to ATP, NADH, and pyruvate.
• Fermentation enables glycolysis in oxygen absence, producing waste (alcohol, lactic acid).
• Pyruvate enters the mitochondria for further oxidation.
• Krebs cycle releases CO₂, synthesizes ATP, and transfers electrons to NADH and FADH₂.
• ETC transfers electrons from the Krebs cycle and glycolysis.
• Gradient of protons across inner mitochondrial membrane drives ATP synthesis.

Cell Structure and Function (3.6 & 2.2)

• Chloroplasts contain stroma (fluid outside thylakoids) and thylakoids in grana stacks.
• Light-dependent reactions in thylakoid membranes.
• Carbon fixation (Calvin Cycle) in stroma.
• Mitochondria's inner membrane folds (cristae) increase surface area for ATP production.

Fitness (3.7)

• Cell variation in molecules (e.g., phospholipids, hemoglobin, chlorophylls) affects an organism's ability to survive and reproduce in varying environments.