bich 409 final (TCA, ETC, Fatty Acids)

T/F: The citric acid cycle is an example of an amphibolic pathway.

true

T/F: In eukaryotes the enzymes of the citric acid cycle are found in the cytosol.

false

T/F: The citric acid cycle is an anaerobic pathway.

false

T/F: The only reaction in the citric acid cycle that produces a carbon-carbon bond is catalyzed by citrate
synthase.

true

T/F: The activated form of eukaryotic pyruvate dehydrogenase complex is the phosphorylated form.

false

What enzymes catalyze an irreversible step in the TCA?

citrate synthase, isocitrate dehydrogenase, α-ketoglutarate dehydrogenase

Which enzyme are unique to the glyoxylate cycle?

isocitrate lyase, malate synthase

The only reaction of the citric acid cycle that provides substrate level phosphorylation is catalyzed by:

Succinyl-CoA synthetase

Which of the following enzyme mechanisms involves a phosphorylated histidine intermediate?

 

Succinate dehydrogenase

 

Isocitrate dehydrogenase

 

Citrate synthase

 

Succinyl-CoA synthetase

 

Pyruvate dehydrogenase

Succinyl-CoA Synthetase

Order the coenzymes according to their involvement in the pyruvate dehydrogenase complex.
1. NAD⁺

2. CoA-SH

3. TPP

4. Lipoamide

5. FAD

3,4,2,5,1

In mammalian tissues, isocitrate dehydrogenase is allosterically stimulated by:

A high NAD⁺/NADH ratio

Which of the following enzyme activities would not be decreased by a thiamine deficiency?

 

Pyruvate carboxylase.

 

Transketolase.

 

All of these enzyme activities would be decreased.

 

α-Ketoglutarate dehydrogenase.

 

Pyruvate dehydrogenase.

Pyruvate carboxylase

Fluoroacetate inhibits the citric acid cycle. Fluoroacetate is metabolized into a product that inhibits:

Aconitase

Which of the following enzymes catalyzes an anaplerotic reaction?

 

Citrate synthase

 

Malate synthase

 

Isocitrate lyase

 

Pyruvate dehydrogenase

 

Pyruvate Carboxylase

Pyruvate carboxylase

The Conversion of citrate into isocitrate by aconitase involves:

A dehydration followed by hydration.

T/F: Electron transport Complexes I, II, III and IV are all proton pumps.

false

The mitochondrial matrix is the site for both fatty acid biosynthesis and fatty acid degradation.

false

Acetyl CoA is required for fatty acid biosynthesis in the cytosol of the cell.  By which mechanism does acetyl CoA leave the mitochondrion and enter the cytosol?

The acetyl CoA condenses with oxaloacetate to form citrate, which is transported into the cytosol where it is cleaved to generate acetyl CoA and oxaloacetate.

The stearoyl-CoA desaturase-catalyzed oxidation of a saturated fatty acid to form an unsaturated fatty acid requires:

NADH and O₂

The committed step of fatty acid biosynthesis is catalyzed by:

Acetyl-CoA carboxylase

There is not a transporter for Acetyl CoA across the inner mitochondrial membrane.  In order to transport acetyl CoA to the cytosol, acetyl CoA must be converted into:

citrate

The formation of acetoacetyl-ACP is catalyzed by:

β-ketacyl-ACP synthase

Acetyl CoA carboxylase is activated by?

citrate and dephosphorylation

T/F: The final acceptor of the electron transport chain is H₂O.

false

T/F: Copper in its cuprous form is Cu²⁺

false

T/F: Cytochromes are iron-containing proteins that carry 2 electrons in the respiratory chain.

false

T/F: The production of ATP by ATP synthase requires energy that is supplied by a sodium ion concentration gradient.

false

T/F: Copper in its cupric form is Cu²⁺

true

Cytochromes:

are proteins with heme prosthetic groups.

The type of gradient that drives ATP synthesis is:

a pH gradient

The protein complexes in the electron transport chain that transfer electrons from succinate to O₂ are:

Complex II, Complex III, and Complex IV.

Cyanide has been used for years to commit murder and is used in gas chambers in executions.
Cyanide:

Coordinates tightly with the heme iron of cytochrome a₃.

The protein complexes in the electron transport chain that transfer electrons from NADH to O₂ are:

Complex I, Complex III, and Complex IV.

The final electron acceptor in the electron transport pathway is:

O₂

Dinitrophenol:

Facilitates the passive transport of hydrogen ions across the inner mitochondrial membrane.

How many electrons are required to reduce O₂ into 2 H₂O?

4

Which of the following can function as a 2 electron carrier?

 

Cytochrome c

 

Fe-S iron sulfer cluster

 

2Fe-2S iron sulfer cluster

 

4Fe-3S iron sulfur cluster

 

Coenzyme Q

Coenzyme Q

Which of the following is a lipophillic free radical scavenger that protects lipids for peroxidation in biological membranes?

Vitamin E

Adding myxothiazol to a suspension of mitochondria inhibits oxygen consumption. The myxothiazol
treated mitochondria have high concentrations of NADH, FMNH₂, Succinate, FADH₂, QH₂, Fe³⁺-
cytochrome b_L, Fe³⁺-cytochrome b_H, Fe³⁺-cytochrome c₁, Fe³⁺ -cytochrome c, Cu_A²⁺ ,Fe³⁺ - cytochrome ,Fe³⁺-cytochrome a₃, and C_uB²⁺.  Based on this information at which electron transport complex is inhibited by myxothiazol?

Complex III

2,4-Dinitrophenol:

Uncouples electron transport from oxidative phosphorylation.

What is the net yield of ATP when Phosphoenolpyruvate is completely oxidized into CO₂ via
glycolysis, citric acid cycle and oxidative phosphorylation. Be sure to include ATPs produced by
substrate level phosphorylations and oxidative phosphorylations coupled to reduced coenzymes.

13.5 atps

The mitochondrial inner membrane contains a transporter for:

ATP

Which one of the following cytochromes is a hydrophilic, mobile electron carrier?

 

Cytochrome a

 

Cytochrome a₃

 

Cytochrome b_L

 

Cytochrome c₁

 

Cytochrome c

cytochrome c

The net ATP obtained per NADH if the glycerol 3-phosphate shuttle is used is:

1.5

Although molecular oxygen does not directly participate in any of the reactions of the citric acid
cycle, the cycle will only operate when oxygen is present. This is because:

O₂ accepts electrons from the electron transport chain, allowing the reoxidation of NADH to NAD⁺.

Menkes disease is a disorder that is characterized by arterial and neuronal degeneration. It is caused
by defective absorption of copper by the intestine. The result is low intracellular concentrations of
copper. A copper defiency would cause a loss of activity of:

Cytochrome c oxidase

In the malate-aspartate shuttle, electrons are carried from the cytosol into the mitochondrial matrix by:

malate

A patient is suffering from lactic acidosis and muscle weakness. The isolated mitochondria of this
patient have high concentrations of NADH, QH₂, and ferric cytochrome c. The mitochondria was
also unable to translocate protons across the inner mitochondrial membrane. From these results the
patient has a defect in:

Cytochrome c reductase

What is the net yield of ATP when glyceraldehyde 3-phosphate is completely oxidized into
CO2 via glycolysis, citric acid cycle, electron transport and oxidative phosphorylation. Using the
Aspartate-Malate shuttle?

17 atp

What is the net yield of ATP when glyceraldehyde 3-phosphate is completely oxidized into
CO₂ via glycolysis, citric acid cycle, electron transport and oxidative phosphorylation.  Using the Glycerophosphate shuttle?

16 atp

Complex I

NADH-CoQ oxidoreductase

Complex II

Succinate-CoQ Dehydrogenase

Complex III

CoQ-Cytochrome C oxidoreductase

Complex IV

Cytochrome C oxidase

Complex I inhibitors

rotenone, demerol, amytal

Complex II inhibitors

carboxin, 2-thenoylfluoroacetone

Complex III inhibitors

Antimycin A1

Complex IV inhibitors

cyanide, azide, carbon monoxide

ATP Synthase Inhibitors

Oligomycin A, Dicylcohexylcarbodiimide (DCCD)

How do uncouplers work?

carry protons from intermembrane space to matrix to disrupt the proton gradient

Enzymes that generate MATRIX NADH

pyruvate dehydrogenase, isocitrate dehydrogenase, α-ketoglutarate dehydrogenase, malate dehydrogenase

Enzymes that generate CYTOSOLIC NADH:

Glyceraldehyde-3-phosphate dehydrogenase, lactate dehydrogenase, glycerol-3-phosphate dehydrogenase, liver alcohol dehydrogenase

Dicarboxylate carrier

Malate, succinate (-) ⇌ phosphate (+)

Aspartate/Glutamate Carrier

Aspartate (-) ⇌ Glutamate (+)

Tricarboxylate Carrier

citrate (-) ⇌ malate (+)

ATP/ADP Translocase

ATP (-) ⇌ ADP (+)

Phosphate Carrier

Phosphate + H⁺ ⇌ Phosphate + H⁺

Pyruvate Translocalase

Pyruvate + H⁺ ⇌ Pyruvate+ H⁺

Symptoms of uncoupler digestion

lethargy, loss of consciousness, fever, tachypnea

E1 of PDH

Pyruvate dehydrogenase

E2 of PDH

Dihydrolipoyl transacetylase

E3 of PDH

dihydrolipoyl dehydrogenase

PDH is inactive when:

phosphorylated

Ketone bodies

Acetoacetate, β-hydroxybutyrate, acetone

-can lower blood pH at high levels