Cellular Energetics & Metabolism

Vocabulary flashcards covering cellular energetics, reaction coupling, ATP, activated carrier molecules, and an overview of metabolism including pathways, redox, and regulation.

Enzymes

Biological catalysts that enhance reaction rates but have no effect on reaction directions.

Reaction coupling

A mechanism where an energetically unfavorable reaction (∆G˚´>0) proceeds forward by being coupled to an energetically favorable reaction (∆G˚´<0).

ATP (adenosine triphosphate)

The energy currency of the cell, used to drive energetically unfavorable reactions through hydrolysis, releasing –7.3 kcal/mol.

Activated carrier molecules

Molecules that store energy in a readily usable form for reaction coupling.

Phosphorylation

The transfer of a γ phosphate from ATP to other molecules.

NADH, NADPH, FADH2

Activated carrier molecules that carry high-energy electrons and hydrogens.

Acetyl CoA

An activated carrier molecule that carries an acetyl group.

S-adenosylmethionine

An activated carrier molecule that carries a methyl group.

Uridine diphosphate glucose

An activated carrier molecule that carries glucose.

NAD+ (nicotinamide adenine dinucleotide)

An electron carrier molecule that carries high-energy electrons (in the form of H:–).

NADP+ (NAD+ phosphate)

An electron carrier molecule similar to NAD+ but with an added phosphate.

Metabolism

The collection of biochemical reactions in a cell, organized into metabolic pathways.

Metabolic pathways

A highly interconnected sequence of biochemical reactions where the product of one reaction is the substrate for the next.

Catabolic pathways

Metabolic pathways that break down complex molecules into simpler products, yielding building blocks and energy.

Anabolic (biosynthetic) pathways

Metabolic pathways that build complex molecules from simpler ones, requiring energy.

Photosynthesis

The process that uses solar energy to synthesize sugars and other molecules.

Cellular respiration

The process that oxidizes sugars as food to provide energy and fixed carbon.

Redox (oxidation-reduction)

The transfer of electrons, where oxidation of carbon releases energy.

Metabolic regulation

The tight control over metabolic pathways to maintain cellular levels of various molecules in a steady state.

Steady state

A condition where cellular levels of various molecules often stay fairly constant.

Covalent modification

A mechanism for regulating enzyme activity, often involving phosphorylation.

Allosteric modulation

A mechanism for regulating enzyme activity where a regulator binds to the enzyme at a site different from the active site.