Cellular Respiration and Electron Transport Chain

Vocabulary based on lecture notes covering redox reactions, complex names in the ETC, and the energetics/efficiency of ATP production from glucose.

Biological Oxidation

A process identified by Antoine Lavoisier in 1770 where food is "combusted" to produce energy, $CO_2$, and $H_2O$; also known as energy metabolism or bioenergetics.

Redox reaction

The combination of oxidation and reduction reactions involving electron ($e^-$) transfer between two substances.

Oxidation

The loss of electrons ($e^-$) during a chemical reaction.

Reduction

The gain of electrons ($e^-$) during a chemical reaction.

Electron Transport Chain (ETC)

A series of electron carriers that transfer electrons from $H$ to $O$ to form $H_2O$, after which oxidative phosphorylation takes place.

Aerobic

A term describing biological processes that require $O_2$ in the mitochondria.

Complex I

NADH dehydrogenase or NADH-Q oxidoreductase.

Complex II

succinate-Q reductase, which contains succinate dehydrogenase.

Complex III

Cytochrome reductase or Q-cytochrome c oxidoreductase.

Complex IV

Cytochrome C oxidase.

Q

An electron carrier in the ETC known as CoQ or ubiquinone.

Cyt C

cytochrome C.

NADH ATP Yield

Production of $3$ ATP molecules per NADH during the electron transport chain.

FADH2 ATP Yield

Production of $2$ ATP molecules per FADH2 during the electron transport chain.

Net ATP production from 1 Glucose

A total of $38$ or $36$ ATP, depending on how glycolytic NADH is transported into the mitochondria.

Total yield from 1 Glucose molecule before ETC

$10 \text{ NADH} + 4 \text{ ATP} + 2 \text{ FADH}_2$.

Molar Energy of ATP

$1 \text{ mole ATP} = 7.3 \text{ kcal}$.

Gross Energy of 1 mole Glucose

$675 \text{ kcal}$ ($180 \text{ g} \times 3.75 \text{ kcal/g}$).

Energy capture efficiency

The efficiency of cellular respiration, calculated at approximately 39 \text{%} ($263 \text{ kcal trapped} / 675 \text{ kcal potential} \times 100$).

Heat

The form of the remaining energy (\text{~}60 \text{%}) from glucose oxidation that is not trapped in ATP.