Mitochondrial Metabolism and ATP Synthesis

This set of vocabulary flashcards covers the components and processes of the mitochondrial electron transport chain, the electrochemical gradient, and the mechanical function of ATP synthase.

Complex III

Also known as cytochrome c reductase, this complex jams electrons onto cytochrome c and uses energy to pump hydrogen ions.

Cytochrome c

A protein that acts as an electron carrier between Complex III and Complex IV; it can also be used as a molecular clock to measure evolutionary distance.

Complex IV

Also known as cytochrome c oxidase, its job is to remove electrons from cytochrome c, pump hydrogen ions, and deposit electrons onto oxygen to form water.

Metabolic Waste Products

The two primary waste products of oxidative metabolism are carbon dioxide ($CO_2$) and water ($H_2O$).

Ubiquinone

A nonprotein electron carrier, also known as an ancient molecule found in nearly every eukaryotic cell, used to carry high energy electrons.

Molecular Clock

A technique that uses the differences in the version of cytochrome c between organisms to determine how evolutionarily distant they are.

Heme

A component held by cytochrome c that contains iron, which is responsible for actually carrying the electrons.

Electrochemical Gradient

A combination of the concentration difference (pH) and the electrical difference (voltage) across the inner mitochondrial membrane that drives hydrogen ion movement.

Complex V

Commonly referred to as the $F_1F_0$ ATP synthase, the enzyme responsible for building ATP.

$F_1$ component

The actual ATPase part of the ATP synthase complex that performs the joining of phosphate to ADP.

$F_0$ component

The transmembrane portion of the ATP synthase, often called the rotor, that spins like a water wheel as hydrogen ions pass through it.

Mechanical Energy

The type of energy produced by the spinning of the $F_0$ rotor and stalk that powers the chemical reaction to create ATP.

Heat Production

The result of chemical reactions in the mitochondria that do not produce a usable product, such as when hydrogen ions bypass the ATP synthase through true channels.

Chemiosmosis

The process of using the hydrogen ion gradient to perform work, such as powering ATP production or transporting molecules like pyruvate and phosphate.

Voltage-driven pump

A transport mechanism powered by the voltage difference across the inner mitochondrial membrane used to exchange ADP into the matrix and ATP out.