Chemotrophic Energy Metabolism: Aerobic Respiration Flashcards

A set of vocabulary flashcards covering the key terms, locations, and processes involved in aerobic respiration and mitochondrial energy metabolism as described in the lecture.

Respiration

The flow of electrons through or within a membrane, from reduced coenzymes to an external electron acceptor usually accompanied by the generation of $ATP$.

Aerobic Respiration

A type of respiration where the terminal electron acceptor is oxygen ($O_2$), and the reduced form produced is water ($H_2O$).

Anaerobic Respiration

A type of respiration used by some organisms (especially bacteria and archaea) where the terminal electron acceptor is a substance other than oxygen, such as sulfur, protons, or ferric ions.

Intermembrane Space

The area located between the outer and inner membranes of the mitochondrion.

Mitochondrial Matrix

The semifluid space found inside the inner mitochondrial membrane.

Cristae

Folds of the inner mitochondrial membrane that function to generate a much greater membrane surface area.

Oxidative Decarboxylation

The process by which pyruvate is oxidized to produce an acetyl group, releasing $CO_2$ and attaching the acetyl group to coenzyme A ($CoA$).

Citric Acid Cycle (CAC)

Also known as the Tricarboxylic Acid Cycle ($TCA$) or Krebs Cycle, it is a series of reactions that complete the oxidation of the two-carbon acetate group to $CO_2$, regenerating oxaloacetate in the process.

$\beta$ oxidation

A repetitive cycle of reactions (oxidation, hydration, reoxidation, and thiolysis) that breaks down fatty acids by removing two carbons at a time to produce one $FADH_2$, one $NADH$, and one acetyl $CoA$ per cycle.

Triacylglycerols

Neutral triesters of glycerol and long-chain fatty acids that serve as a primary storage form of fat.

Proteolysis

The breakdown of proteins into amino acids catalyzed by enzymes called proteases.

Electron Transport

The process of coenzyme reoxidation by the transfer of electrons from reduced coenzymes ($NADH$ and $FADH_2$) to oxygen via an ordered series of carriers.

Electron Transfer Chain (ETC)

A multistep process involving an ordered series of reversibly oxidized electron carriers (integral membrane proteins) located in the inner mitochondrial membrane.

Standard Reduction Potential ($E'_0$)

An experimental measure (in volts, $V$) of the affinity of a redox pair for electrons.

Respiratory Complexes

Large assemblies of proteins in the mitochondrial inner membrane where most electron transport intermediates occur.

Oxidative Phosphorylation

The synthesis of $ATP$ that is coupled to oxygen-dependent electron transport.

Proton Motive Force (PMF)

An electrochemical proton gradient established by the directional pumping of protons ($H^+$) across the membrane during electron transport.

$F_o$ complex

A hydrophobic assembly of polypeptides embedded in the mitochondrial inner membrane that serves as a channel for proton diffusion.

$F_1$ complex

A molecular motor protrusion consisting of $\text{knoblike spheres}$ that serves as the site for $ATP$ production in the mitochondrial matrix.

Electron Shuttle System

A system used to pass electrons and $H^+$ ions from cytosolic $NADH$ into the mitochondrial matrix since $NADH$ cannot cross the membrane directly.

Thermogenin

A protein channel in the inner membrane of brown fat cells that allows facilitated transport of protons, dissipating the energy of the gradient as heat instead of using it for $ATP$ synthesis.

Binding Change Model

A model for $ATP$ synthesis where the rotation of the $\text{γ}$ subunit, powered by proton movement, induces conformational changes in the three $\text{β}$ subunits to catalyze $ATP$ production.