BIOC13H3 Final Examination Review: Oxidative Phosphorylation and Metabolism

Comprehensive vocabulary flashcards covering the Electron Transport Chain, oxidative phosphorylation, mitochondrial structures, and chemical inhibitors based on the BIOC13H3 lecture materials.

Oxidative Phosphorylation

The production of ATP using energy released from electron transfer reactions occurring in the inner mitochondrial membrane, requiring NADH, $FADH_2$, and Oxygen.

Complex I (NADH Dehydrogenase)

An enzyme that accepts electrons from NADH, transfers them to Coenzyme Q, and pumps $4 \text{ } H^+$ ions into the intermembrane space to begin proton gradient formation.

Complex II (Succinate Dehydrogenase)

A component of both the TCA cycle and ETC that transfers electrons from $FADH_2$ to Coenzyme Q but does NOT pump protons.

Complex III (Cytochrome bc1 Complex)

A major amplification step that transfers electrons from $CoQH_2$ to cytochrome c and pumps $4 \text{ } H^+$ into the intermembrane space.

Complex IV (Cytochrome c Oxidase)

The final enzyme in the ETC that transfers electrons from Cytochrome C to $O_2$ (the final electron acceptor) to produce $H_2O$ and pumps $4 \text{ } H^+$ per $O_2$ reduced.

Proton Motive Force (PMF)

The electrochemical gradient produced by the pumping of protons ($H^+$) across the inner mitochondrial membrane by Complexes I, III, and IV.

Pyruvate Dehydrogenase Complex (PDC)

A multi-enzyme complex that converts Pyruvate ($3C$) into Acetyl-CoA ($2C$), releasing $CO_2$ and producing NADH in a process known as pyruvate oxidation.

ATP Synthase (Complex V)

A reversible, rotary molecular nanomotor that converts the energy stored in the electrochemical proton gradient into ATP.

$F_0$ Region

The membrane-embedded domain of ATP synthase that functions as a proton channel and contains the rotating c-ring.

$F_1$ Region

The catalytic domain of ATP synthase that protrudes into the mitochondrial matrix and contains the $\beta$ subunits where ATP is synthesized.

Binding Change Mechanism

A theory describing how the rotation of the \text{\gamma} subunit induces conformational changes in $\beta$ subunits to cycle through L (Loose), T (Tight), and O (Open) states to synthesize ATP.

Chemiosmotic Theory

A theory proposed by Peter Mitchell (awarded the 1978 Nobel Prize) explaining that electron transport creates a proton gradient used to power ATP synthesis.

Rotenone

A chemical inhibitor that targets Complex I, stopping electrons from NADH from entering the Electron Transport Chain.

Antimycin A

A chemical inhibitor that blocks electron transfer within the cytochrome bc1 complex (Complex III).

Cyanide ($CN^-$)

A Complex IV inhibitor that prevents oxygen from accepting electrons, effectively stopping the electron transport chain.

Oligomycin

An inhibitor that targets ATP synthase ($F_0F_1$) by blocking proton ($H^+$) flow, thereby stopping ATP production.

Uncouplers

Agents like DNP (2,4-dinitrophenol) that dissipate the proton gradient, allowing electron transport to continue while stopping ATP synthesis.

Carbon Monoxide (CO)

A toxic gas that competes with oxygen for binding at the heme $a_3$-$Cu_B$ center of Complex IV, causing histotoxic hypoxia.

Dr. John Rubinstein

A U of T researcher whose lab uses high-resolution cryo-electron microscopy (cryo-EM) to study the structures of ATP synthases and V-type ATPases.

ATP Yield of NADH and $FADH_2$

In the mitochondria, typically one NADH produces $2.5 \text{ } ATP$ and one $FADH_2$ produces $1.5 \text{ } ATP$.