Chapter 7: The Common Catabolic Pathway

Flashcards about the Citric Acid Cycle, Electron Transport Chain, and ATP Biosynthesis.

What is another name for the Citric Acid Cycle?

Krebs cycle and tricarboxylic acid cycle

What products are generated by the Citric Acid Cycle?

2 CO2, 1 GTP or ATP, 3 NADH/H+, 1 FADH2

Define a Metabolon.

A group of enzymes performing reactions with a common purpose.

What is substrate channeling?

The diversion of the product of one enzymatic reaction directly into a subsequent reaction, to increase reaction rate and efficiency.

What is the first step in the Citric Acid Cycle, catalyzed by Citrate Synthase?

Condensation of acetyl CoA with oxaloacetate to produce citrate

What reaction does Aconitase catalyze?

Isomerization of citrate to isocitrate

What is produced during the oxidation of isocitrate to α-ketoglutarate?

NADH

What is the rate-determining step in the Citric Acid Cycle?

Oxidation of α-ketoglutarate to succinyl-CoA.

What is generated during substrate-level phosphorylation by Succinyl CoA Synthetase?

ATP or GTP

Which enzyme catalyzes the oxidation of succinate?

Succinate Dehydrogenase

What is the role of Fumarase in the citric acid cycle?

Catalyzes a hydration reaction.

What is the role of anaplerotic reactions?

To replenish levels of citric acid cycle intermediates.

What happens during transamination reactions?

Amine groups are shuttled to α-ketoglutarate to generate glutamate and a new α-keto acid.

What is the role of ATP Synthase?

Multimeric enzyme that uses electrochemical energy from the proton gradient to produce ATP from ADP and Pi

Where does the Electron Transport Chain occur?

In the matrix and inner mitochondrial membrane.

Name two important mitochondrial shuttles.

Glycerophosphate shuttle and Aspartate-malate shuttle

How many H+ are pumped out of the mitochondrial matrix by Complex I?

4H+

Which complex does not pump protons out of the matrix?

Complex II

What is transferred by Complex III?

Electrons are transferred to cytochrome c

What is the Q Pool?

Combination of oxidized and reduced forms of ubiquinone found in the mitochondrial membrane

What does Complex IV do?

Takes 4e− from cytochrome c, Pumps 2H+ out of the mitochondrial matrix, Reduces O2 to H2O

What is a Respirasome?

Aggregated supercomplex containing Complexes I, III, and IV.

What is the effect of uncouplers on the electron transport chain?

Interfere with electron transport, generating heat instead of ATP.

What is Proton motive force?

The electrochemical potential derived from the uneven distribution of electrons across the inner mitochondrial matrix.

What is transported by ATP: ADP translocase?

ATP from the mitochondria in exchange for ADP

Name some different types of ATPases.

F-type, A-type, V-type, P-type, E-type