energy in living systems

Redox reactions

Chemical reactions involving the transfer of electrons, where oxidation and reduction occur simultaneously.

Oxidation

A reaction that involves the loss of electrons from an atom or molecule.

Reduction

A reaction that involves the gain of electrons by an atom or molecule.

NAD+

The oxidized form of nicotinamide adenine dinucleotide, a key electron carrier in cellular metabolism.

NADH

The reduced form of NAD+, formed when it accepts two electrons and a proton.

FAD+

The oxidized form of flavin adenine dinucleotide, another important electron carrier.

FADH2

The reduced form of FAD+, formed when it accepts electrons.

ATP

Adenosine triphosphate, often referred to as the energy currency of the cell.

Hydrolysis of ATP

Process that breaks down ATP into ADP and releases energy.

Phosphorylation

The addition of a phosphate group to a molecule, often to activate or modify it.

Substrate-level phosphorylation

Direct generation of ATP from ADP using a phosphate group from a substrate during glycolysis.

Oxidative phosphorylation

The production of ATP from the electron transport chain and chemiosmosis, involving oxygen.

Chemiosmosis

The movement of ions across a selectively permeable membrane, generating ATP using a proton gradient.

Reducing agent

A compound that donates electrons in a redox reaction, becoming oxidized in the process.

Oxidizing agent

A compound that accepts electrons in a redox reaction, becoming reduced in the process.