The Electron Transport Chain and ATP Synthesis

A set of vocabulary flashcards covering the components of the electron transport chain, the movement of protons, and the mechanics of ATP synthesis according to the chemiosmotic theory.

Complex I

The first enzyme complex in the electron transport chain that pulls electrons off of $NADH$, converting it to $NAD^+$, and pumps a proton out from the mitochondrial matrix into the intermembrane space.

Complex II

The enzyme complex that accepts electrons from $FADH_2$, converting it to $FAD$, but lacks a pore to pump protons across the membrane.

Coenzyme Q

A non-protein, mobile molecule also known as ubiquinone that accepts electrons from Complex I and Complex II and carries them to Complex III.

Complex III

Also referred to as cytochrome B, this complex accepts electrons from coenzyme Q, passes them to cytochrome C, and pumps a proton into the intermembrane space.

Cytochrome C

A special mobile molecule made of a cytochrome with a heme structure and a central iron that accepts electrons from Complex III and passes them to Complex IV.

Complex IV

Also called cytochrome oxidase, this complex accepts electrons from cytochrome C, passes them to oxygen, and pumps a proton into the intermembrane space.

Oxygen

The final electron acceptor in the electron transport chain that combines with two electrons and two protons to produce water ($H_2O$).

ATP synthase

Known as complex V, this structure uses the potential energy from the movement of protons down their concentration gradient to convert $ADP$ and inorganic phosphate into $ATP$.

Mitochondrial Matrix

The internal compartment of the mitochondria where the Krebs cycle occurs and where protons are pumped from.

Intermembrane space

The area between the inner and outer mitochondrial membranes where protons accumulate, creating a high concentration or electrochemical gradient.

Chemiosmotic Theory

The theory stating that as protons move from high concentration to low concentration, $ATP$ synthase absorbs potential energy to synthesize $ATP$.

Oxidative phosphorylation

The specific type of phosphorylation that occurs in the electron transport chain where $ATP$ is produced using energy from the proton gradient.

Substrate level phosphorylation

The method of $ATP$ production used directly within glycolysis and the Krebs cycle, rather than via the electron transport chain.

Catalytic knob

The part of $ATP$ synthase containing alpha and beta subunits where the actual synthesis of $ATP$ from $ADP$ and inorganic phosphate takes place.

Beta subunit

The specific subunit of the catalytic knob on $ATP$ synthase that holds $ADP$ and inorganic phosphate and uses potential energy to fuse them into $ATP$.

$$36\,ATP$$

The approximate net amount of $ATP$ produced from one glucose molecule through aerobic cellular respiration alone.

$$38\,ATP$$

The total amount of $ATP$ produced in whole from one glucose molecule, combining the $36\,ATP$ from aerobic processes and the $2\,ATP$ from anaerobic glycolysis.