05/12 05 Energy, Enzymes, and Cellular Respiration Free Online FlashCards

What is metabolism?

Metabolism is the complete set of chemical reactions occurring in a cell or organism.

What do enzymes change in a reaction?

Enzymes lower activation energy, allowing reactions to proceed faster without changing ΔG or the equilibrium constant.

Why does enzyme rate plateau at high substrate concentration?

At high substrate concentration, most active sites are occupied, so the enzyme becomes saturated and the rate approaches a maximum.

What does ATP hydrolysis produce?

ATP hydrolysis is ATP + H₂O → ADP + Pᵢ + free energy. Its released energy can drive active transport or macromolecule synthesis.

What do oxidation and reduction mean?

Oxidation is the loss of electrons or hydrogen atoms; reduction is their gain.

Where does glycolysis occur, and what does it produce?

Glycolysis occurs in the cytosol and splits one glucose into two pyruvate molecules through ten steps.

What is glycolysis's net yield per glucose?

The net yield per glucose is 2 pyruvate, 2 ATP, and 2 NADH. Four ATP form, but two are invested earlier.

What happens during pyruvate oxidation?

Pyruvate oxidation removes one carbon as CO₂ and attaches the remaining two-carbon fragment to coenzyme A, forming acetyl-CoA.

What does one turn of the citric acid cycle produce?

For each acetyl-CoA, it produces 2 CO₂, 3 NADH, 1 FADH₂, and 1 ATP or GTP.

How does the electron transport chain create a proton gradient?

The electron transport chain uses electron-transfer energy to pump H⁺ into the intermembrane space, creating an electrochemical gradient.

How does ATP synthase make ATP?

ATP synthase uses the flow of H⁺ through its membrane channel to drive conformational changes that catalyze ADP + Pᵢ → ATP.

What is oxygen's role in aerobic respiration?

Oxygen is the terminal electron acceptor in aerobic respiration. It combines with electrons and H⁺ to form water.