Enzyme Basics, Kinetics, and Cellular Reactions (Video Notes)

Vocabulary flashcards covering key terms from enzyme biology and reaction kinetics from the video notes.

Catabolic reactions

Reactions that break down complex molecules into simpler ones, releasing energy.

Anabolic reactions

Reactions that build larger molecules from smaller ones, using energy.

Condensation (dehydration synthesis) reactions

Join monomers to form covalent bonds with release of water.

Hydrolysis reactions

Break covalent bonds by adding water; splits molecules.

Enzyme

A globular protein that acts as a biological catalyst, lowering activation energy by binding substrates at the active site.

Globular protein

A soluble, roughly spherical protein typical of many enzymes.

Active site

Region of the enzyme where substrate binds and the reaction occurs; formed by a few amino acids.

Substrate

The molecule(s) that bind to the enzyme and undergo the chemical reaction.

Induced fit model

Binding of substrate induces a conformational change in the enzyme, producing a tight, specific fit.

Lock-and-key model

Old idea that substrate fits perfectly into a rigid active site without changing shape.

Primary structure

The sequence of amino acids in a protein; determines shape and functional features including the active site.

Amino acids

Building blocks of proteins; twenty different kinds; linked to form polypeptides.

Denaturation

Permanent alteration of a protein's shape and function due to high temperature or extreme pH.

Optimal temperature

The temperature at which an enzyme works best; beyond this, activity declines due to denaturation.

Optimal pH

The pH at which an enzyme has maximal activity; deviations reduce activity or denature the enzyme.

Substrate concentration effect

Increasing substrate concentration raises reaction rate until all active sites are saturated.

Activation energy

Minimum energy needed for a reaction to occur; enzymes lower this barrier.

Saturation / maximum rate

Point at which all enzyme active sites are occupied; increasing substrate no longer increases rate.

Intracellular vs extracellular enzymes

Intracellular enzymes catalyze reactions inside cells (e.g., glycolysis, Krebs cycle); extracellular enzymes act outside cells (e.g., digestive enzymes in gut).

Calvin cycle

Part of photosynthesis in plants; carbon fixation cycle that converts CO2 into sugars.