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Biochemistry 316 : Metabolism > Past midterms > Flashcards

Past midterms Flashcards

1
Q

Which of these are mismatched ?

A. Pyruvate
B. Citrate
C. Glyoxalate
D. Malate
E. Ribose-5-phosphate

A

D. Malate

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2
Q

Which of the following statements about carbohydrates is CORRECT?

A. Mannose is an epimer of galactose.

B. Glycolysis occurs in the mitochondrion.

C. Galactose is a component of amylose.

D. Fructose is a 5-carbon ketose.

E. Lactose is a reducing sugar

A

Which of the following statements about carbohydrates is CORRECT?

E. Lactose is a reducing sugar

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3
Q

Insulin increases the:

A. rate of glycogen phosphorylase

B. rate of liver fructose bisphosphatase-2

C. levels of liver intracellular cAMP

D. levels of liver fructose-2,6-bisphosphate

E. number of GLUT2 glucose transporters on muscle cell membranes

A

D. levels of liver fructose-2,6-bisphosphate

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4
Q

During long-term starvation, the preferred energy source for the muscle is:

A. fatty acids only
B. ketone bodies only
C. both glucose and ketone bodies
D. both glucose and fatty acids
E. glucose, ketone bodies and fatty acids

A

E. glucose, ketone bodies and fatty acids

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5
Q

Which of the following represents the CORRECT sequence of intermediates in the citric acid cycle? (note: not all intermediates are shown in each set)

A. citrate, isocitrate, succinate, succinyl CoA, oxaloacetate
B. citrate, α-ketoglutarate, succinate, oxaloacetate, malate
C. isocitrate, α-ketoglutarate, succinyl CoA, fumarate, malate
D. isocitrate, succinyl CoA, α-ketoglutarate, malate, oxaloacetate
E. α-ketoglutarate, succinate, oxaloacetate, malate, citrate

A

C. isocitrate, α-ketoglutarate, succinyl CoA, fumarate, malate

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6
Q

Which of the following statements about the citric acid cycle is CORRECT:

A. it DIRECTLY generates lots of water which can be used by the cell
B. it DIRECTLY generates 1 GTP, 3 NADH and 1 FADH2 per cycle
C. it can be used by vertebrates to generate glucose from excess acetyl CoA
D. it produces two molecules of CO2 from molecular oxygen
E. it involves two decarboxylation reactions involving biotin as a coenzyme

A

B. it DIRECTLY generates 1 GTP, 3 NADH and 1 FADH2 per cycle

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7
Q

The Triglyceride shown below is:

A. 1-Stearoyl, 2-linoleoyl, 3-linolenoyl glycerol
B. 1-Palmitoyl, 2-linolenoyl, 3-linoleoyl glycerol
C. 1-Palmitoyl, 2-linolenoyl 3-oleoyl glycerol
D. 1-Palmitoyl, 2-linoleoyl, 3-linolenoyl glycerol
E. 1-Stearoyl, 2-linolenoyl, 3-linoleoyl glycerol

A

D. 1-Palmitoyl, 2-linoleoyl, 3-linolenoyl glycerol

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8
Q

Using the compositional data in the table below select the combination which best fit lipoprotein particle descriptors for Lipoprotein A & B respectively:

A

VLDL and Chylomycron

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9
Q

Which of the following is NOT an intermediate on the pathway from an essential fatty acid to docosahexaenoic acid (DHA) 22:6 Δ 4,7,10,13,16,19

A. 18:3 Δ 9,12,15
B. 18:4 Δ 6,9,12,15
C. 20:5 Δ 5,8,11,14,17
D. 22:5 Δ 4,7,10,13,16
E. 24:6 Δ 6,9,12,15,18,21

A

D. 22:5 Δ 4,7,10,13,16

Note that its not an ω-3

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10
Q

Which of the following statements regarding ketogenesis/ketone body utilization is CORRECT:

A. ketone bodies are made exclusively in the liver and kidney
B. ketone body use by the heart depends upon oxaloacetate supply by PEP carboxykinase
C. thiokinase is required for the first step of ketogenesis
D. ketogenesis involves the cytosolic enzyme HMG-CoA synthase
E. ketone body utilization is absent from the brain due to the blood-brain barrier

A

B. ketone body use by the heart depends upon oxaloacetate supply by PEP carboxykinase

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11
Q

Which of the following statements about ω-oxidation is CORRECT:

A. it involves a mixed-function oxidase to oxidize the C-1 carbon
B. it involves sequentially acid, aldehyde and alcohol
C. it occurs in the peroxisome
D. it prepares the fatty acid for β-oxidation
E. it uses a flavoprotein oxidase to recycle FAD

A

D. it prepares the fatty acid for β-oxidation

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12
Q

The tissue expression pattern of which of the following enzymes CHANGES DURING STARVATION:

A. Glycerol kinase in the adipocyte.
B. Glucose-6-phosphatase in the muscle
C. 3-ketoacyl CoA transferase in the liver
D. Hexokinase IV in the heart
E. Thiolase in the brain.

A

​E. Thiolase in the brain.

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13
Q

Type II Question:
Which of the following enzymes is/are IRREVERSIBLE

  1. glucose 6-phosphatase
  2. glucokinase
  3. fructose 1,6-bisphosphatase
  4. pyruvate kinase
A

All are correct

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14
Q

Type II Question:

Peroxisomal fatty acid β-oxidation involves:

  1. oxidation of medium chain (C10-C12) fatty acids
  2. export of NADH + H+ to mitochondria for reoxidation
  3. export of FADH2 to mitochondria for reoxidation
  4. export of acetyl CoA to mitochondria
A

2 and 4 are correct

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15
Q

Type II Question

The synthesis of glycogen involves:

  1. linear chains of 12-14 glucose molecules coupled via (β1->4) linkages
  2. β1->6 branches at the approximately rate of 2 per linear chain
  3. activated GTP-glucose
  4. the combination of three different enzymes to couple the glucose units
A

Only 4 is correct

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16
Q

Type II Question

Adipocyte triglyceride lipolysis:

  1. involves sequentially: hormone sensitive lipase, adipocyte triglyceride lipase & monoglyceride lipase
  2. phosphorylation of perilipin to reveal the triglyceride substrate
  3. dephosphorylation of hormone sensitive lipase in order to activate it
  4. eventual release of fatty acids and glycerol into the bloodstream
A

Only 2 and 4 are correct

Note that #1 is out of order

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17
Q

Type II question

Coenzyme A contains within its structure:

  1. ribose
  2. adenosine
  3. β-mercaptoethylamine
  4. nicotinamide
A

only 1, 2, and 3

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18
Q

Type II Question

Which of the following enzymes/pathways is CORRECTLY listed with one of its DIRECT metabolic products

  1. pyruvate dehydrogenase- acetyl CoA
  2. glyoxalate cycle- sucrose
  3. pentose phosphate pathway- ribose-5-P
  4. citric acid cycle-ATP
A

1 and 3

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19
Q

Type II question

The Glyoxalate Cycle involves which of the following enzymes:

  1. malate synthase
  2. malate dehydrogenase
  3. isocitrate lyase
  4. aconitase
A

All of the above

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20
Q

Type II Question

Which of the following enzymes depends upon pyrophosphatase to drive it:

  1. fructose-1,6-bisphosphatase
  2. acetyl CoA synthetase
  3. succinyl CoA synthetase
  4. UDP-glucose pyrophosphorylase
A

2 and 4

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21
Q

Type II Question:

Which of the following enzymes uses thiamin pyrophosphate as co-enzyme:

  1. pyruvate carboxylase
  2. transketolase
  3. isocitrate dehydrogenase
  4. pyruvate dehydrogenase
A

2 and 4

22
Q

Type II Question

Pentose Phosphate Pathway:

  1. involves oxidative steps that generate NADPH and ribose-5-phosphate
  2. involves non-oxidative steps that convert ribulose-5-phosphate back to glucose-6-phosphate
  3. can use non-oxidative steps in reverse to generate ribose-5-phosphate without NADPH
  4. enables the body to make cholesterol
A

All are correct

23
Q

Type II Question

Which of the following statements about the synthesis of arachidonic acid and eicosapentaenoic acid (EPA) from essential fatty acids is (are) CORRECT

  1. the process involves alternating steps of first a) desaturation and then b) elongation
  2. the sequence of the desaturase enzymes is always: 4-desaturase, 5-desaturase, 6-desaturase
  3. cis-double bonds can be introduced up to but not beyond C-9 by mammalian enzymes
  4. desaturases generate a conjugated double bond system
A

1 and 3

24
Q

Type II Question

Pyruvate carboxylase:

  1. has a biotin carboxylase subunit
  2. requires ATP
  3. has a transcarboxylase subunit to make oxaloacetate
  4. has a biotinidase activity to recycle biotin
A

1, 2, and 3

25
Q

Type II Question

Which of the following statements regarding the carnitine transport system is (are) CORRECT?

  1. the fatty acid carrier, carnitine is a product of lysine and methionine
  2. the carnitine transport system is stimulated by malonyl CoA
  3. it uses cytosolic and matrix pools of CoA which are distinct and separate
  4. the carnitine transporter has a dual role as a acyl carnitine transferase and pump
A

1 and 3

26
Q

Which of the following molecules is INCORRECTLY matched with its name?

A. Pyruvate
B. Citrate
C. Glyoxalate
D. Glycerol
E. Malate

A

E Malate

27
Q

Which of the following statements about carbohydrates is CORRECT?

A. Mannose is an epimer of glucose.
B. Glycolysis occurs in the mitochondria.
C. Galactose is a component of sucrose.
D. Fructose is an aldohexose.
E. Sucrose is a reducing sugar

A

A

28
Q

Glucagon increases the:

A. rate of glycogen synthase
B. rate of glycogen branching
C. levels of liver intracellular cAMP
D. levels of liver fructose-2,6-bisphosphate
E. number of GLUT4 glucose transporters on muscle cell membranes

A

C. levels of liver intracellular cAMP

29
Q

NADPH is produced by which of the following enzyme:

A. pyruvate dehydrogenase
B. isocitrate dehydrogenase
C. malate dehydrogenase
D. α-ketoglutarate dehydrogenase
E. glucose-6-P-dehydrogenase

A

​ E. glucose-6-P-dehydrogenase

Part of the Pentose phosphate pathway

30
Q

Which of the following represents the CORRECT sequence of intermediates in the citric acid cycle? (note that not all intermediates are shown in each set)

A. citrate, α-ketoglutarate, succinate, oxaloacetate, malate
B. isocitrate, α-ketoglutarate, succinyl CoA, fumarate, malate
C. citrate, isocitrate, succinate, succinyl CoA, oxaloacetate
D. isocitrate, succinyl CoA, α-ketoglutarate, malate, oxaloacetate
E. α-ketoglutarate, succinate, oxaloacetate, malate, citrate

A

B. isocitrate, α-ketoglutarate, succinyl CoA, fumarate, malate

31
Q

Which of the following statements about the citric acid cycle is CORRECT:

A. it DIRECTLY generates lots of water which can be used by the cell
B. it DIRECTLY generates ATP, NAD and 2 FAD per cycle
C. it can be used by vertebrates to generate glucose from excess acetyl CoA
D. it is used to synthesize glutamate and purines for nucleic acid biosynthesis
E. it involves two decarboxylation reactions involving biotin as a coenzyme

A

D. it is used to synthesize glutamate and purines for nucleic acid biosynthesis

32
Q

The Triglyceride shown below is:

A. 1-Stearoyl, 2-linoleoyl, 3-linolenoyl glycerol
B. 1-Palmitoyl, 2-linolenoyl, 3-linoleoyl glycerol
C. 1-Palmitoyl, 2-linolenoyl 3-oleoyl glycerol
D. 1-Stearoyl, 2-linolenoyl, 3-linoleoyl glycerol
E. 1-Palmitoyl, 2-linoleoyl, 3-linolenoyl glycerol

A

A. 1-Stearoyl, 2-linoleoyl, 3-linolenoyl glycerol

33
Q

Using the compositional data in the table below select the combination which best fit lipoprotein particle descriptors for Lipoprotein A & B respectively:

A

LDL and VLDL

34
Q

Which of the following is NOT an intermediate on the pathway from an essential fatty acid to docosahexaenoic acid (DHA) 22:6 Δ 4,7,10,13,16,19

A. 18:3 Δ 9,12,15
B. 18:4 Δ 6,9,12,15
C. 22:5 Δ 4,7,10,13,16
D. 20:4 Δ 8,11,14,17
E. 20:5 Δ 5,8,11,14,17

A

C. 22:5 Δ 4,7,10,13,16

35
Q

Which of the following statements about ketone bodies is CORRECT:

A. ketone bodies are used by ALL tissues of the body including the fasting brain
B. ketone body use depends upon oxaloacetate supply by pyruvate carboxylase
C. thiokinase is required for the first step of ketogenesis
D. ketone bodies are usually synthesized from alanine, lactate or glycerol
E. ketone bodies are absent in patients with myopathic carnitine deficiency

A

B. ketone body use depends upon oxaloacetate supply by pyruvate carboxylase

A is incorrect because the liver does not use ketones

36
Q

Which of the following statements about ω-oxidation is CORRECT:

A. it involves a mixed-function oxidase to oxidize the C-1 carbon
B. it involves sequentially acid, aldehyde and alcohol
C. it does not actually shorten the fatty acid chain
D. it readies the fatty acid for peroxisomal oxidation
E. it uses a flavoprotein oxidase to recycle FAD

A

C. it does not actually shorten the fatty acid chain

37
Q

Type II Question

Gluconeogenesis involves which of the following irreversible enzymatic steps:

  1. glucose-6-phosphatase
  2. pyruvate carboxylase
  3. PEP carboxykinase
  4. phosphofructokinase 2
A

1, 2, and 3

38
Q

Type II Question

UDP-glucose is involved in

  1. fructose catabolism
  2. galactose catabolism
  3. mannose catabolism
  4. glycogen synthesis
A

2 and 4

39
Q

Type II Question

Glycogen and starch both contain:

  1. chains of glucose residues joined by (β1-4) linkages
  2. branches to additional glucose chains joined by (α1-6) linkages
  3. glycogenin at their core
  4. a relatively hydrated structure when present inside the cell
A

2 and 4

40
Q

Type II question

In human tissues all the pathways that pyruvate can take:

  1. are aerobic
  2. provide equal amounts of ATP to the cell
  3. lower the pH of the cell
  4. eventually reoxidise NADH to NAD+
A

4 only

41
Q

Type II question

A ganglioside contains within its structure:

  1. serine
  2. sphingosine
  3. palmitate
  4. complex sugars eg. N-acetyl galactosamine
A

All of the above

42
Q

Type II question

The Pentose Phosphate Pathway

  1. includes irreversible oxidative steps
  2. generates nucleic acid precursors
  3. includes reversible non-oxidative steps
  4. represents one of the few sources of NADH for biosynthesis
A

4

43
Q

Type II question

The Glyoxalate Cycle involves which of the following enzymes:

  1. citrate synthase
  2. malate synthase
  3. isocitrate lyase
  4. malate dehydrogenase
A

All of the above

44
Q

Type II Question

Regulation of glycolysis occurs at which of the following steps:

  1. hexokinase-I
  2. phosphofructokinase -1
  3. pyruvate kinase
  4. glyceraldehyde 3-phosphate dehydrogenase
A

1, 2, and 3

45
Q

Type II question

Mitochondrial β-oxidation:

  1. generates one molecule of FADH2 & one molecule of NADPH per cycle
  2. is regulated at Step 3 by the end-product acetyl CoA
  3. involves a dehydration at Step 2
  4. generates 28 ATPs per palmitate molecule representing about 25% of the total available energy
A

4 only

46
Q

Type II question

Pancreatic Lipase:

  1. requires a co-lipase to activate it
  2. like all lipases, it hydrolyses triglyceride to glycerol and three fatty acids
  3. requires bile salts to create a lipid emulsion
  4. requires energy in the form of ATP
A

1 and 3

47
Q

Type II question

Several coenzymes are incorporated within the structure of pyruvate dehydrogenase complex, These include:

  1. FAD
  2. NADH
  3. lipoic acid
  4. biotin
A

1 and 3

48
Q

Type II question

Which of the following statements about elongation of essential fatty acids is (are) CORRECT

  1. the process generally involves alternating steps of a) desaturases followed by b) elongases
  2. the sequence of the desaturase enzymes is always: 6-desaturase, 5-desaturase, 4-desaturase
  3. the process extends ω-6 and ω-3 fatty acids equally efficiently
  4. trans-double bonds can be introduced up to but not beyond C-9 by mammalian enzymes
A

1 and 3

49
Q

Type II question

Which of the following forms a covalent derivative with a fatty acid:

  1. cholesterol
  2. fatty acid-binding protein
  3. coenzyme A
  4. albumin
A

1 and 3

50
Q

Type II question

Which of the following describes fatty acid transport into the mitochondrial matrix?

  1. It is the rate-limiting step in fatty acid β-oxidation
  2. It is regulated by [malonyl CoA]
  3. The cytosolic and matrix pools of CoA are distinct and separate
  4. Once fatty acyl groups enter the matrix, they are committed to oxidation to acetyl CoA
A

All of the above

Biochemistry 316 : Metabolism (7 decks)

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