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BIOCHEMISTRY - 1st Year 1st Sem Comprehensive Exam > PRELIM - Respiratory chain, Overview of metabolism, and TCA > Flashcards

PRELIM - Respiratory chain, Overview of metabolism, and TCA Flashcards

1
Q

The following are true roles of vitamins in citric acid cycle, except:

a. Riboflavin in the form of Flavin Adenine Dinucleotide, co-factor in alpha ketoglutarate dehydrogenase complex and succinate dehydrogenase
b. Niacin in the form of Nicotinamide Adenine Dinucleotide, co-enzyme for the 3 dehydrogenases in the cycle (isocitrate, malate and alpha ketoglutarate
c. Thiamin as thiamin diphosphate, coenzyme for decarboxylation in the alpha ketoglutarate dehydrogenase reaction
d. Pantothenic acid as part of co-enzyme A, co-factor attached to ‘active’ carboxylic acid residues such as acetyl CoA and succinyl CoA
e. No exception

A

e. No exception

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2
Q

The following are major metabolic features of the liver, except:

a. Major pathways: Glycolysis, gluconeogenesis, lipogenesis, beta oxidation, citric acid cycle, ketogenesis, lipoprotein metabolism, synthesis of bile salts, urea, uric acid, cholesterol, plasma proteins
b. Main substrates: Glucose, amino acids in prolonged starvation
c. Main products: Glucose, triacylglycerol in VLDL, ketone bodies, urea, uric acid, bile salts, cholesterol, Plasma proteins
d. Specialist Enzymes: Glucokinase, glucose 6-phosphatase, glycerol kinase, PEP-CK, fructokinase, arginase, HMG CoA synthase, HMG CoA lyase, alcohol dehydrogenase
e. No exception

A

b. Main substrates: Glucose, amino acids in prolonged starvation

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3
Q

All are true regarding the Citric Acid Cycle, except:

a. Series of reactions in the mitochondria that oxidizes acetyl residues
b. Final common pathway for aerobic oxidation of carbohydrates, lipids, amino acids
c. Central role in gluconeogenesis, lipogenesis and interconversion of amino acids
d. Upon reoxidation, linked to the formation of ATP
e. No exception

A

e. No exception

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4
Q

How many ATPs are generated via oxidative phosphorylation alone?

a. 8
b. 9
c. 10
d. 11
e. 12

A

d. 11

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5
Q

How many ATPs are yielded from conversion of succinyl CoA to succinate?

a. 4
b. 3
c. 2
d. 1
e. 0

A

d. 1

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6
Q

How many ATPs are yielded from oxidation of one molecule of acetyl CoA using both substrate level and oxidative phosphorylation?

a. 8
b. 9
c. 10
d. 11
e. 12

A

e. 12

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7
Q

Which cell organelle contains enzymes for TCA cycle?

a. Cytosol
b. ER
c. Mitochondria
d. Ribosome

A

c. Mitochondria

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8
Q

How many ATP’s are generated from the oxidation of one molecule of NADH in electron transport chain?

a. 0
b. 1
c. 2
d. 3
e. 4

A

d. 3

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9
Q

How many ATP’s are generated from the oxidation of one molecule of FADH2?

a. 0
b. 1
c. 2
d. 3
e. 4

A

c. 2

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10
Q

Enzyme which catalyzes condensation of Acetyl CoA and Oxaloacetate to form Citrate?

a. Aconitase
b. Citrate Synthase
c. Isocitrate Dehydrogenase
d. Succinyl CoA Thiokinase
e. None of the Above

A

b. Citrate Synthase

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11
Q

Which of the following allosterically activates the enzyme cited in question number 14?

a. Calcium
b. ADP
c. ATP
d. Both A&B
e. Both A&C

A

d. Both A&B

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12
Q

The following inhibits the enzyme cited in question number 14, except:

a. ATP
b. NADH
c. Succinyl CoA
d. ADP
e. Fatty acyl CoA derivatives

A

d. ADP

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13
Q

Citrate is isomerized to isocitrate this enzyme:

a. Aconitase
b. Citrate Synthase
c. Isocitrate Dehydrogenase
d. Succinyl CoA Thiokinase
e. None of the Above

A

a. Aconitase

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14
Q

Catalyzes the irreversible oxidative decarboxylation of isocitrate, yielding the first of three NADH molecules produced by the cycle and the first release of CO2:

a. Aconitase
b. Citrate Synthase
c. Isocitrate Dehydrogenase
d. Isocitrate Decarboxylase
e. None of the Above

A

c. Isocitrate Dehydrogenase

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15
Q

Conversion of alpha-ketoglutarate to succinyl CoA is catalyzed by which enzyme complex? This reaction releases second CO2 and produces 2nd NADH of the cycle.

a. Cytochrome P450 complex
b. Alpha-Ketoglutarate Dehydrogenase Complex
c. Alpha-Ketoglutarate Decarboxylase Complex
d. Pyruvate Dehydrogenase Complex
e. None of the Above

A

b. Alpha-Ketoglutarate Dehydrogenase Complex

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16
Q

The coenzymes required for above reaction include the following, except:

a. Thiamine Pyrophosphate
b. NADH
c. Lipoic Acid
d. FAD
e. Coenzyme A

A

b. NADH

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17
Q

This enzyme, cleaves the high energy thioester bond of succinyl CoA to form succinate:

a. Aconitase
b. Citrate Synthase
c. Succinyl CoA Thioketolase
d. Succinyl CoA Thiokinase
e. None of the Above

A

d. Succinyl CoA Thiokinase

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18
Q

Which reaction is considered the substrate-level phosphorylation in TCA cycle?

a. Generation of FADH2 by Succinate Dehydrogenase
b. Generation of GTP by Succinate Thiokinase
c. Generation of CO2 by Alpha-Ketoglutarate Dehydrogenase Complex
d. Generation of One molecule of H+ plus another molecule of NADH by Malate Dehydrogenase

A

b. Generation of GTP by Succinate Thiokinase

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19
Q

Succinate is oxidized to fumarate by this enzyme:

a. Succinyl CoA Thiokinase
b. Succinate Dehydrogenase
c. Succinate Decarboxylase
d. Fumarase
e. None of the Above

A

b. Succinate Dehydrogenase

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20
Q

Fumarate is hydrated to malate in a freely reversible reaction catalyzed by what enzyme:

a. Succinyl CoA Thiokinase
b. Succinate Dehydrogenase
c. Succinate Decarboxylase
d. Fumarase
e. None of the Above

A

d. Fumarase

21
Q

Malate is oxidized to oxalate by what enzyme?

a. Malate Dehydrogenase
b. Fumarase
c. Malate Oxidase
d. Malate Decarboxylase

A

a. Malate Dehydrogenase

22
Q

The conversion of Pyruvate to Acetyl CoA and CO2 is:

a. Reversible
b. Involves participation of Lipoic Acid
c. Activated when pyruvate dehydrogenase complex is phosphorylated by a protein kinase in the presence of ATP
d. Happening inside the cytosol
e. Dependent on the coenzyme Biotin

A

b. Involves participation of Lipoic Acid

23
Q

Which of the following conditions decrease the oxidation of acetyl CoA by the Citric Acid Cycle?

a. A low ATP/ADP ratio
b. A low NADH due to rapid oxidization to NAD+ through respiratory chain
c. A low NAD+/NADH ratio
d. A high concentration of AMP
e. A low GTP/GDP ratio

A

c. A low NAD+/NADH ratio

24
Q 
The following is the sum of three steps in the citric acid cycle:
A + B + FAD + H2O → C + FADH2 + NADH
Reactant A Reactant B Reactant C
a. Succinyl CoA    GDP  Succinate
b. Succinate   NAD+   Oxaloacetate
c. Fumarate.  NAD+   Oxaloacetate
d. Succinate   NAD+.  Malate
e. Fumarate   GTP    Malate
A

b. Succinate NAD+ Oxaloacetate

25
Q

Endodermic, involved in the synthesis of larger and more complex compounds from small precursors.

a. Amphibolic pathway
b. Anabolic pathway
c. Catabolic pathway
d. Metabolic pathway

A

b. Anabolic pathway

26
Q

Amino acids metabolism involves

a. Transamination
b. Dehydrogenation
c. Decarboxylation
d. Deamination

A

a. Transamination

27
Q

The following are stages of respiration EXCEPT

a. Pyruvate to acetyl CoA
b. Citric Acid Cycle
c. Oxidative Phosphorylation
d. None of the above
e. All choices are stages respiration

A

e. All choices are stages respiration

28
Q

Glycolysis occurs in which part of the cell?

a. Inner mitochondrial matrix
b. Outer mitochondrial matrix
c. Cytoplasm
d. Nucleus
e. None of the above

A

c. Cytoplasm

29
Q

Other term for Citric Acid Cycle?

a. Krebs Cycle
b. Tricarboxylic Acid
c. Oxidative Phosphorylation
d. A and B
e. A and C

A

d. A and B

30
Q

Part of coenzyme A. Cofactor attached to acetyl CoA and succinyl CoA

a. Riboflavin
b. Vitamin B1
c. Niacin
d. Pantothenic Acid

A

d. Pantothenic Acid

31
Q

The following are co factors of the alpha ketoglutarate complex except

a. Thiamine diphosphate
b. Lipoate
c. NAD+
d. Acetyl CoA
e. None of the above

A

d. Acetyl CoA

32
Q

Not true about the Citric Acid Cycle upon taking part in Fatty acid Synthesis:

a. Acetyl-CoA is the major substrate for long long-chain fatty acid synthesis in nonruminants
b. Pyruvate dehydrogenase is a mitochondrial enzyme, and fatty acid is a cytosolic pathway
c. Mitochondrial membrane is permeable to Acetyl-CoA
d. Citrate is cleaved by citrate lyase to form oxaloacetate
e. All of the choices are true

A

c. Mitochondrial membrane is permeable to Acetyl-CoA

33
Q

Which of the following is/are mismatched regarding Respiratory Chain inhibition?

a. Barbiturates inhibits Complex II
b. Antimycin A and Dimecapol inhibit Complex I
c. Malonate inhibit Complex II
d. Both A and B

A

d. Both A and B

34
Q

This enzyme contains FAD and iron sulfur (Fe-S) protein, and directly reduces ubiquinone in the electron transport chain.

a. Succinate thiokinase
b. Succinate dehydrogenase
c. Isocitrate dehydrogenase
d. Fumarase

A

b. Succinate dehydrogenase

35
Q

Repercussions of the destruction of hepatic cells in which it is replaced by connective tissue

a. Hepatomegaly
b. Hepatitis A
c. Cirrhosis
d. Diabetic ketoacidosis

A

c. Cirrhosis

36
Q

What substance accumulates due to arsenite inhibiting pyruvate oxidation?

a. α-ketoglutarate
b. pyruvate carboxylase
c. cis-aconate
d. citrate

A

a. α-ketoglutarate

37
Q

The key enzyme that catalyzes net transfer out of the cycle into gluconeogenesis

a. α-ketoglutarate
b. Thiophorase
c. Transaminase
d. Phosphoenolpyruvate carboxykinase

A

d. Phosphoenolpyruvate carboxykinase

38
Q

What refers to #1, 2, 3, and 4 in the image?

a. 1. disaccharides 2. polypeptides 3. Fatty acids 4. acetyl-CoA
b. 1. Simple sugars (glucose) 2. Amino acids 3.fatty acids 4. acetyl-CoA
c. 1. Simple sugars (glucose) 2. Amino acids 3. Fatty acids 4. Pyruvate
d. 1. Disaccharides 2. polypeptides 3. Fatty acids 4. Pyruvate

A

b. 1. Simple sugars (glucose) 2. Amino acids 3.fatty acids 4. acetyl-CoA

39
Q

Important substrate that combines with Acetyl CoA for citric acid cycle to proceed.

a. Oxaloacetate
b. Malate
c. CO2
d. H20

A

a. Oxaloacetate

40
Q

What type of reducing molecule is formed for every action of the enzyme dehydrogenase?

a. FADH2
b. GTP
c. NADH
d. Both a and b

A

c. NADH

41
Q

During chemiosmosis:

a. H+ ions serve as the final electron acceptor
b. a concentration gradient is generated when H+ ions are passively transported from the matrix to the intermembrane space of the mitochondrion
c. energy is released as H+ ions move freely across the mitochondrial membrane
d. ATP is synthesized when H+ ions move through a channel in ATP synthase

A

d. ATP is synthesized when H+ ions move through a channel in ATP synthase

42
Q

How many molecules of acetyl CoA, an acetyl group attached to ‘coenzyme A’, are produced from a single molecule of glucose for participation in the Krebs cycle?

a. 1
b. 2
c. 4
d. 3

A

b. 2

43
Q

Non-essential amino acids can’t be formed by the body.

a. True
b. False

A

b. False

44
Q

Carbon dioxide (CO2) is released during which of the following stages of cellular respiration?

a. glycolysis and the oxidation of pyruvate to acetyl CoA
b. oxidation of pyruvate to acetyl CoA and the citric acid cycle
c. oxidative phosphorylation and fermentation
d. fermentation and glycolysis

A

b. oxidation of pyruvate to acetyl CoA and the citric acid cycle

45
Q

Starting with one molecule of glucose, the energy-containing products of glycolysis are _____.

a. 2 NAD+, 2 pyruvate, and 2 ATP
b. 2 NADH, 2 pyruvate, and 2 ATP
c. 2 FADH2, 2 pyruvate, and 4 ATP
d. 6 CO2, 2 pyruvate, and 2 ATP

A

b. 2 NADH, 2 pyruvate, and 2 ATP

46
Q

In respiration, beta oxidation involves the _____.

a. oxidation of glucose
b. oxidation of pyruvate
c. regulation of glycolysis
d. breakdown of fatty acids

A

d. breakdown of fatty acids

47
Q

_____ are important components of Complexes I and II.

a. Oxidoreductase
b. iron sulfur proteins
c. flavoproteins
d. succinate-Q-reductase

A

c. flavoproteins

48
Q

_________lack mitochondria and hence are wholly reliant on glycolysis and the pentose phosphate pathway at all times.

a. Lymphocytes
b. Erythrocytes
c. both a and b
d. none of the above

A

b. Erythrocytes

49
Q
  1. All of the following are formed on the inner membrane of mitochondria, EXCEPT:
    a. Complex II
    b. ATP synthase
    c. Q
    d. Acyl CoA synthetase
A

d. Acyl CoA synthetase

BIOCHEMISTRY - 1st Year 1st Sem Comprehensive Exam (16 decks)

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