Chapter 3- Cell Metabolism

Activation Energy

Additional energy that molecules must acquire in order to react; the difference between the energy of the transition state and the energy of the reactants or products

ATP

Compound that serves as the primary direct energy source for cell activities; synthesized from adenosine diphosphate and inorganic phosphate

Affinity

A measure of how tightly ligand molecules bind to proteins

Allosteric Regulation

Regulatory mechanism in which a modulator binds reversibly to the regulatory site on an enzyme, inducing a change in its conformation and activity

Anabolism

Synthesis of large molecules from smaller molecules, generally requiring an input of energy

ATP Synthase

The enzyme that synthesizes adenosine triphosphate during oxidative phosphorylation; located in the inner mitochondrial membrane

Beta Oxidation

Metabolic pathway that catabolizes fatty acids to acetyl coenzyme A

Calorie

Amount of energy that must be put into one gram (or one milliliter) of water to raise its temperature by one degree celsius under a standard set of conditions

Catabolism

Breakdown of large molecules into smaller molecules; generally releases energy

Catalytic Rate

For enzyme catalyzed reactions, a measure of the number of reactants converted to product per unit time

Chemiosmotic Coupling

The entire process that couples electron transport to adenosine triphosphate synthesis; the utilization of energy released during electron transport to transport hydrogen ions across the inner mitochondrial membrane up their concentration gradient

Coenzymes

Molecules that do not themselves have catalytic activity but that are necessary for proper enzyme function and participate directly in reactions catalyzed by enzymes; often serve to transfer certain chemical groups from one reactant to another

Cofactors

Nonprotein components of some enzymes necessary for them to hold normal conformation during metabolic reactions

Covalent Regulation

Regulatory mechanism in which changes in an enzyme’s activity are brought about by the covalent bonding of a specific chemical group to a site on the enzyme molecule; usually involves bonding of a phosphate group

Electron Transport Chain

A series of electron acceptors and other proteins in the inner mitochondrial membrane; involved in the synthesis of ATP by oxidative phosphorylation

Energy

Capacity to do work

Energy Metabolism

Set of reactions involved in energy storage and use

Enzymes

Biomolecules, usually proteins, specialized to act as catalysts in metabolic reactions

Equilibrium

A condition of no change without requiring energy expenditure; in chemical reactions, when the rates of the forward and reverse reactions are equal

Essential Nutrient

Any biomolecule necessary for proper body function that cannot by synthesized in cells and, therefore, must be obtained from dietary sources

Feedback Inhibition

Regulatory mechanism in which an enzyme in a metabolic pathway is inhibited by an intermediate appearing downstream

Feedforward Activation

Regulatory mechanism in which an enzyme in a metabolic pathway is stimulated by an intermediate appearing upstream

Gluconeogenesis

Process during which new glucose molecules can be synthesized from noncarbohydrate precursors by the liver

Glycogen

A glucose polymer found in animal cells; functions as an energy store

Glycogenesis

Synthesis of glycogen from glucose monomers

Glycogenolysis

Breakdown of glycogen to glucose monomers

Glycolysis

The first stage of glucose oxidation, occurring in the cytosol, in which each glucose molecule is broken down to two molecules of pyruvate

Hydrolysis

Use of water to split another molecule

Kinetic Energy

Energy associated with motion

Krebs Cycle

A cyclical metabolic pathway occurring in the mitochondrial matrix, in which acetyl coenzyme A is a primary reactant and carbon dioxide and reduced coenzymes are produced

Law of Mass Action

States that a reaction can be made to go either forward or in reverse by raising or lowering the concentrations of reactants relative to products