Energy, Enzymes, and Metabolism Vocabulary

Flashcards covering key vocabulary terms from a lecture on energy, enzymes, and metabolism.

Catalyst

Agent that speeds up the rate of a chemical reaction without being consumed during the reaction.

Enzymes

Protein catalysts in living cells.

Ribozymes

RNA molecules with catalytic properties.

Activation Energy (EA)

The energy required to start a reaction by breaking bonds in the reactant molecules.

Transition State

Unstable state where bonds are stretched during a reaction.

Spontaneous Reaction

Reactions that occur without input of additional energy; may not necessarily be fast.

Substrate

Reactant molecule on which an enzyme acts.

Active Site

Region on the enzyme in which the substrate binds.

Enzyme-Substrate Complex

Enzyme + Substrate

Vmax

Maximum velocity of reaction near maximum rate, when nearly all active sites are occupied by substrate

Michaelis Constant (KM)

Substrate concentration where velocity is half of maximum.

Competitive Inhibition

Molecule binds to active site and inhibits ability of substrate to bind; apparent KM increases.

Noncompetitive Inhibition

Inhibitor binds to allosteric site, not active site; lowers Vmax without affecting KM.

Metabolism

Sum of all chemical reactions that take place in a cell.

Catabolic Pathways

Breakdown cellular components; exergonic pathways.

Anabolic Pathways

Synthesis cellular components; endergonic pathways.

Exergonic Reactions

Reactions that release energy by breaking down complex molecules.

Endergonic Reactions

Reactions that consume energy to build complex molecules.

Substrate-Level Phosphorylation

Enzyme directly transfers phosphate from one molecule to another molecule; oxygen not needed.

Chemiosmosis (Oxidative Phosphorylation)

Energy stored in an electrochemical gradient is used to make ATP from ADP and Pi.

Oxidation

Removal of electrons.

Reduction

Addition of electrons.

NAD+

Oxidized form of Nicotinamide adenine dinucleotide.

NADH

Reduced form of Nicotinamide adenine dinucleotide; energy intermediate.

Feedback Inhibition

Product of pathway inhibits early steps to prevent over accumulation of product.

Proteasome

Complex including protease enzymes that break down proteins

Ubiquitin

Tags target proteins to the proteasome to be broken down and recycled.

Half-Life

Time it takes for 50% of the molecules to be broken down and recycled.