Vocab Unit 3 Enzymes & Energy

What is an enzyme?

A biological catalyst that speeds up chemical reactions.

What is a substrate?

The specific reactant an enzyme acts upon.

What is the active site of an enzyme?

The pocket where the substrate binds to the enzyme.

What is activation energy?

The minimum energy required to start a reaction.

What is a competitive inhibitor?

A molecule that blocks the active site from the substrate.

What is a noncompetitive inhibitor?

A molecule that binds elsewhere to change the enzyme's shape.

What is an allosteric site?

A site other than the active site where molecules bind to regulate activity.

What is an endergonic reaction?

A reaction that requires an input of energy.

What is an exergonic reaction?

A reaction that releases energy into the environment.

What is photosynthesis?

The process of converting light energy into chemical energy (glucose).

What is chlorophyll?

A pigment that absorbs light for photosynthesis.

What is a thylakoid?

Membrane discs where light-dependent reactions occur.

What is the stroma?

The fluid where the Calvin Cycle occurs.

What is cellular respiration?

The process of breaking down glucose to create ATP energy.

What is ATP?

The main energy-carrying molecule in the cell.

What is glycolysis?

The first step of respiration; it breaks glucose in the cytosol.

What is the Krebs Cycle?

A mitochondrial process that releases CO2 and charges electrons.

What is the Electron Transport Chain (ETC)?

A protein sequence that creates a proton gradient.

What is ATP synthase?

An enzyme that produces ATP using proton flow.

What is fermentation?

An anaerobic process to regenerate NAD+ without oxygen.

What is the equation for photosynthesis?

$$6CO_2 + 6H_2O + \text{light} \rightarrow C_6H_{12}O_6 + 6O_2$$

What is the equation for cellular respiration?

$$C_6H_{12}O_6 + 6O_2 \rightarrow 6CO_2 + 6H_2O + \text{ATP}$$

What is a misconception about inhibitor binding?

Competitive inhibitors compete for the active site; noncompetitive inhibitors bind to the allosteric site, changing the shape of the active site so the substrate no longer fits.

What is activation energy?

The 'energy barrier' that must be overcome for a reaction to proceed. Enzymes work by lowering this barrier.

How does ATP synthase function?

ATP synthase acts like a turbine; as protons (H+) flow through it, it spins to 'recharge' ADP into ATP.