CHY 205 Chapter Notes - Chapter 16: Pyruvate Dehydrogenase Complex, Isocitrate Dehydrogenase, Dihydrolipoamide Dehydrogenase

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The oxidation of pyruvate to h2o & co2 in aerobic conditions is called respiration, more specifically cellular respiration which refers to molecular processes by which cells consume. This occurs in 3 stages: 1) acetyl-coa production: organic fuel molecules, eg. glc, fa & some aa, are oxidized to form acetyl-coa. Glc to pyruvate via glycolysis & pyruvate to acetyl-coa via pyruvate dehydrogenase complex. 2) acetyl-coa oxidation: acetyl groups are fed into cac which enzymatically oxidizes them to co2, the energy released is conserved in reduced e- carriers nadh & fadh2. This stage generates more nadh, fadh2, 1 gtp/atp. 3) e- transfer & oxidative phosphorylation: the reduced coenzymes are themselves oxidized giving up h+ & e- which are transferred to o2, the final e- acceptor via the respiratory chain. This e- flow drives the production of atp in what is known as oxidative phosphorylation.

Related Questions

7. In metabolism, food gets oxidized and the coenzymes NAD⁺ and FAD are reduced.

	True
	False

8. Which of the following does not undergo oxidation or reduction during metabolism?

	A. lipids
	B. Coenzyme A
	C. carbohydrates
	D. FAD

9. Which of the following is not a coenzyme?

	A. NAD⁺
	B. Coenzyme A
	C. ATP
	D. FAD

10. Which of the following is false regarding FAD?

	A. FAD is an oxidizing agent.
	B. FAD is the oxidized form.
	C. FAD is a coenzyme
	D. FADH₂ is an oxidizing agent.

11. How many carbon atoms are present in an acetyl group?

	A. 1
	B. 2
	C. 3
	D. 4

12. The purpose of coenzyme A is to deliver acetyl groups to the citric acid cycle.

	True
	False

13. What reacts with NADH and FADH₂ to form NAD⁺ and FAD?

	A. carbon dioxide
	B. water
	C. ATP
	D. oxygen (and H⁺)

14. Which metabolic process oxidizes NADH and FADH₂

	A. electron transport chain
	B. oxidative phosphorylation
	C. citric acid cycle
	D. hydrolysis

15. Which metabolic process converts ADP to ATP?

	A. electron transport chain
	B. oxidative phosphorylation
	C. citric acid cycle
	D. hydrolysis

1. Oxygen atoms present in CO2 that is released in the Kreb's cyclecome from-

a. Molecular oxygen (O2)
b. Acetyl CoA
c. H2O
d. Acetyl CoA and H2O
e. NADH + H+

2. How many ATP are obtained by substrate-level phosphorylationduring a complete oxidation of a single glucose molecule (includeGlycolysis, PDH reaction and the Krebs' cycle, do NOT subtract"energy investment")

a. 1
b. 2
c. 4
d. 6
e. 32

3. One of the differences between the isocitrate dehydrogenasereaction and the alpha-ketoglutarate dehydrogenase reactionis:

a. only one of them is an oxidative decarboxylation reaction
b. only one of them uses CoA-SH as the source for one electron(hydrogen)
c. only one of them uses NAD+ as the electron (hydrogen)carrier
d. only one of them requires ATP
e. only one of them yields ATP (or GTP)

4. Which of the following would most likely act as an inhibitor ofthe enzymes of the citric acid cycle?

a. high concentration of ADP
b. high concentration of ATP
c. high concentration of NADH
d. high concentration of NAD+
e. more than one of the above

2. In many cases, cellular signal transduction is mediated by a membrane-associated G-protein complex. Which is not right about this protein complex?

A) The complex is made of Î±-, Î²-, and Î³-subunit.

B) The G_sÎ±-subunit has a GTPase activity.

C) Depending on the receptor types, either G_sÎ±-subunit or G_iÎ±-subunit is used.

D) Signal transduction through G-proteins ultimately regulates protein phosphorylation.

E) None of the above.

3. Which statement is not right about the pyruvate dehydrogenase?

A) This enzyme is located in the mitochondria.

B) This enzyme consists of three different enzymatic subunits (E1, E2, and E3).

C) This enzyme catalyzes the reaction: Pyruvate + CoA + NAD Â® Acetyl-CoA + CO₂ + NADH

D) This enzyme also uses TPP (thiamine pyrophosphate), lipoic acid, and FAD as cofactors.

E) Despite its complexity, this enzyme is not an important regulation point of TCA cycle.

4. To maintain a proper rate of the TCA cycle, oxaloacetate is replenished periodically. To increase [oxaloacetate], ___X____ is turned on but the TCA cycled is turned off by phosphorylation of __Y__.

A) X = Glyoxylate cycle :::::: Y = isocitrate dehydrogenase

B) X = Glyoxylate cycle :::::: Y = isocitrate lyase

C) X = Q cycle :::::: Y = isocitrate dehydrogenase

D) X = Q cycle :::::: Y = isocitrate lyase

E) None of the above.

5. Assume you have three NADH and one FADH₂. Calculate the total numbers of H⁺ pumped into the inter-membrane space and the maximal number of ATP produced inside the matrix.

A) 40 H⁺ and 12 ATP
B) 40 H⁺ and 11 ATP
C) 36 H⁺ and 12 ATP

D) 36 H⁺ and 11 ATP
E) None of the above.

CHY 205 Chapter Notes - Chapter 16: Pyruvate Dehydrogenase Complex, Isocitrate Dehydrogenase, Dihydrolipoamide Dehydrogenase

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