2.1 Introduction to Metabolism and Enzyme Activity

VOCABULARY flashcards covering the introductory concepts of metabolism, catabolism, anabolism, enzyme function, enzyme classifications, and redox reactions.

Metabolism

The sum of all of the different chemical reactions in a cell, fundamental for cellular functioning and physiology.

Catabolic pathways

Metabolic processes that digest and break apart larger molecules into smaller ones or building blocks, overall releasing energy.

Anabolic pathways

Metabolic processes that build up molecules, such as muscles from steroids, which requires energy.

Monomers

The smaller molecules or building blocks resulting from the breakdown of larger molecules in catabolic pathways.

Enzyme

A protein that catalyzes a specific chemical reaction.

Catalysis

The acceleration of a reaction by making it more energetically favorable.

Activation energy

The necessary energy needed to overcome the barrier for a chemical reaction to occur; enzymes function by lowering this.

Reactant

The substance you start with before a chemical reaction takes place.

Product

The substance that is formed after a chemical reaction takes place.

Cofactors

Metal ions, such as zinc, that can activate or enhance an enzyme's activity.

Substrate

The specific target molecule of an enzyme.

Active site

The component of the enzyme that binds to the substrate.

Induced fit

The process where the binding of a substrate brings chemical groups of the active site into positions that enhance catalysis.

Specificity

The selectiveness of an enzyme for one particular type of substrate.

Denaturing

The unfolding of a protein's structure, often due to high temperature, which affects the structure of the active site and halts enzyme function.

Proteases

Enzymes that break down proteins.

Lipases

Enzymes that break down lipids.

Amylase

An enzyme that breaks down starches.

Catalase

An enzyme that breaks down hydrogen peroxide ($H_2O_2$) into water ($H_2O$) and oxygen ($O_2$).

Lysozyme

An antimicrobial enzyme found in saliva, mucus, and tears that cleaves polysaccharide chains in bacterial cell walls.

Hydrolases

Enzymes that catalyze hydrolysis, the breaking of chemical bonds with the addition of water ($H_2O$).

Isomerases

Enzymes that catalyze the rearrangements of bonds within a molecule to produce an isomer.

Ligases (Bond Formation)

Enzymes that form covalent bonds between two separate molecules.

Ligases (Bond Cleavage)

Enzymes that cleave or break bonds in a manner other than hydrolysis.

Oxoreductases

Enzymes that transfer electrons from a reductant (electron donor) to an oxidant (electron acceptor).

Transferases

Enzymes that transfer a functional group, such as a phosphate, acetyl, or methyl group, to a molecule.

Kinases

A type of transferase that phosphorylates or attaches a phospho group to another molecule.

Oxidation-reduction reaction

Also known as redox reactions, these involve the transfer of electrons which carry energy between molecules.

Electron acceptor

A molecule that accepts an electron, reducing its overall charge to be more negative (e.g., from $0$ to $-1$).

Electron donor

A molecule that loses an electron, often donating it to oxygen.

Oxidation

The loss of electrons during a chemical reaction, remembered by the acronym OIL (Oxidation Involves Loss).

Reduction

The gain of electrons during a chemical reaction, remembered by the acronym RIG (Reduction Involves Gain).

Activated carrier

A molecule like $NADH$ that carries electrons and energy to various parts of the cell for energy production.

NADH

The high-energy, reduced form of $NAD$ that has gained and carries electrons.

NAD

The oxidized form of the energy carrier that is ready to accept electrons.