Define diffusion
Passive movement of molecules from high to low concentration.
Define osmosis
Diffusion of water across a selectively permeable membrane.
How does the sodium‑potassium pump work?
Pumps 3 Na⁺ out and 2 K⁺ in using ATP; maintains membrane potential.
How temperature affects enzymes
High temp denatures proteins; low temp slows reaction rate.
How pH affects enzymes
Enzymes have optimal pH; deviation alters ionization and active site shape.
Active site
Region of enzyme where substrate binds and reaction occurs.
Transition state
High‑energy intermediate formed during the reaction pathway.
Substrate
Molecule an enzyme acts upon.
Purpose of glycolysis
Breaks glucose into 2 pyruvate; produces 2 ATP & 2 NADH.
What happens in pyruvate oxidation?
Pyruvate → Acetyl‑CoA + CO₂ + NADH.
Citric acid cycle products
Per glucose: 2 ATP, 6 NADH, 2 FADH₂, 4 CO₂.
Electron transport chain function
Creates proton gradient using electron flow; drives ATP synthase.
Role of O₂ in ETC
Final electron acceptor; forms water.
Chemiosmosis
Protons flow through ATP synthase to generate ATP.
ATP synthase
Enzyme that converts proton gradient energy into ATP.
Autotroph definition
Organism that produces its own organic molecules (e.g., plants).
Heterotroph definition
Organism that consumes organic molecules for energy.
What is a photon?
A discrete packet of light energy that excites electrons in photosynthesis.
Purpose of light reactions
Generate ATP and NADPH; split water to supply electrons.
Purpose of Calvin cycle
Fix CO₂ into G3P using ATP and NADPH.
RuBP role
5‑carbon molecule that reacts with CO₂ in the Calvin cycle.
G3P
Three‑carbon sugar produced by Calvin cycle; building block for glucose.
Define ligand
A signaling molecule that binds to a receptor.
Define kinase
Enzyme that phosphorylates (adds phosphate groups) to proteins.
