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Biochem 2 Final > Old Quizzes and Exams > Flashcards

Old Quizzes and Exams Flashcards

1
Q

You just woke up from a good night’s sleep. Indicate for each metabolic enzyme whether it is likely ACTIVE or INACTIVE in the liver»» pyruvate carboxylase, pyruvate kinase, PFK-1, glucose-6-phosphatase, glucokinase, PEP carboxykinase

A

pyruvate carboxylase (active)
pyruvate kinase (inactive)
PFK-1(inactive)
glucose-6-phosphatase (active)
glucokinase (inactive)
PEP carboxykinase (active)

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2
Q

Complete the scheme in the attached image with the name of either a metabolite or pathway for the labels 1-4

A
  1. Glycolysis
  2. gluconeogenesis
  3. Acetyl-CoA
  4. TCA cycle
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3
Q

T/F insulin-stimulated glucose uptake in muscle is mediated by all four types of glucose transporters (GLUT1-4)

A

false

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4
Q

T/F under anaerobic conditions, conversion of Pyruvate to Lactate provides a way for a cell to enable glycolysis to proceed

A

true

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5
Q

which of the following statements BEST describes the reason why acetyl-CoA cannot be converted to pyruvate?

A

the conversion of pyruvate to acetyl-CoA results in shortening the carbon chain, making it impossible to reverse the reaction

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6
Q

cyanide inhibits ATP synthesis by?

A

preventing proton transport through complex 4

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7
Q

the enzyme __ is involved in defense mechanisms against ROS-induced damage?

A

superoxide dismutase

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8
Q

other than reducing the production of ATP, what is the other effect that mitochondrial uncouplers have?

A

uncouplers increase the generation of heat by the mitochondria

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9
Q

the liver cannot utilize ketone bodies as a source for energy because

A

the liver lacks the enzyme Thiophorase that converts acetoacetic acid to acetoacetyl-CoA

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10
Q

Oxaloacetate is an intermediate in both gluconeogenesis and the TCA cycle. These pathways occur in the cytosol
and mitochondria, respectively. In order for oxaloacetate to cross the mitochondrial membrane, it must first be
converted to either _______ or _______

A

aspartate; malate

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11
Q

what step is the commitment step of gluconeogenesis starting from pyruvate?

A

oxaloacetate –> phosphoenolpyruvate

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12
Q

the initial reaction in glycolysis is not the commitment step because

A

glucose-6-phosphate can be utilized in other pathways

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13
Q

PFK-1 is inhibited by

A

both ATP and citrate

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14
Q

which of the following completes the redox reaction: Lactate + NAD+ <->

A

pyruvate + NADH + H+

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15
Q

that main mechanism by which metabolic enzymes are regulated is

A

allosteric activation/ inhibition

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16
Q

T/F rapidly growing cancer cells use less glucose than normal cells, which is called the Warburg effect

A

false

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17
Q

what enzymes catalyze the three irreversible steps of glycolysis in the liver

A

glucokinase, 6-phosphofructo-1-kinase, and pyruvate kinase

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18
Q

T/F nucleoside analogs are more effective drugs than nucleotide analogs because the activation of nucleotides is much slower

A

false

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19
Q

T/F if both fatty acid oxidation and fatty acid synthesis are active in the liver cells, they will form a futile cycle and waste ATP

A

true

20
Q

T/F the human body synthesizes more cholesterol than we normally obtain from diet

A

true

21
Q

T/F glutamine is the most abundant circulating amino acid

A

true

22
Q

T/F threonine is metabolized to succinyl CoA, which is an intermediate in the tricarboxylic acid (TCA) cycle. therefore, threonine is a ketogenic amino acid

A

false

23
Q

which amino acid is used as the precursor for the synthesis of y-aminobutyrate (GABA)

A

glutamate

24
Q

which of the following statements on cAMP is incorrect

A

its level in the liver cells is decreased upon the release of glucagon

25
Q

which of the following statements is incorrect about the reaction of epinephrine on the heart?

A

stimulates gluconeogenesis

26
Q

which enzyme is NOT activated in liver cells upon the release of insulin

A

PEP carboxykinase

27
Q

he pathway for the catecholamine synthesis is shown below. Fill in the name of each metabolite.

A

tyrosine
L-DOPA
dopamine
norepinephrine
epinephrine

28
Q

which of the following statements is incorrect

A

uric acid is another name for the acid form of urea

29
Q

Complete the transamination reaction shown below. The structures of α-ketoglutarate and oxaloacetate are shown to
help you.
α-ketoglutarate + aspartate ⇔ _____________ + oxaloacetate

A

glutamate

30
Q

_______ delivers cholesterol to the peripheral tissues. The uptake of this lipoprotein by the liver is critical for the
feedback inhibition of the de novo cholesterol synthesis. The high levels of this lipoprotein in blood is known to
increase the risk of atherosclerosis

A

LDL

31
Q

Which of the following descriptions is incorrect about HMG-CoA reductase

A

cholesterol activates HMG-CoA reductase

32
Q

which of the following is least soluble

A

cholesterol ester

33
Q

which of the following statements is incorrect about fatty acid oxidation

A

fatty acid oxidation occurs in the cytosol

34
Q

which of the following describes the total metabolites required for the synthesis of one palmitate in human

A

8 acetyl CoA + 7 ATP + 14 NADPH

35
Q

he following reaction is the commitment step for the fatty acid synthesis. What is the product of this reaction

A

malonyl CoA

36
Q

which of the following statements is FALSE concerning the reaction catalyzed by Hexokinase

A

it is the commitment step of glycolysis

37
Q

high intake of sucrose increases the risk of obesity because

A

fructose metabolism bypasses the highly regulated PFK-1 step in glycolysis

38
Q

Pyruvate dehydrogenase uses a complex mechanism to convert pyruvate to acetyl-CoA. Which of
the following is NOT a substrate, product or coenzyme in the pyruvate dehydrogenase reaction

A

ATP

39
Q

which of the following is false regarding Flavin coenzymes

A

they are highly polar and hydrophilic

40
Q

which component of ETS is also an enzyme in the TCA cycle

A

succinate dehydrogenase/ Complex 2

41
Q

which of the following statements is incorrect about the metabolism of fatty acids

A

malonyl-CoA promotes fatty acid oxidation

42
Q

The hydrolysis of one triacylglycerol generates one glycerol and three fatty acids. How many
glucose molecule(s) can be synthesized through gluconeogenesis from two molecules of
triacylglycerol?

A

1

43
Q

Which of the following shows the correct order of solubility (from the HIGHEST to the LOWEST) of cholesterol,
cholesterol ester, and cholic acid?

A

chalice acid > cholesterol > cholesterol ester

44
Q

which of the following descriptions on lipoproteins is incorrect

A

HDL deliver cholesterol from the liver to the peripheral tissues

45
Q

which of the following is incorrect about metabolism of amino acids

A

branched amino acids (Val, Leu, and Ile) are all nonessential amino acids in human

46
Q

Complete the transamination reaction shown below. The structure of pyruvate is shown to help you.
α-ketoglutarate + ___________ ⇌ glutamate + pyruvate

A

alanine

47
Q

which of the following pairs of amino acids and their derivatives is INCORRECT

A

aspartate - oxalate

Biochem 2 Final (2 decks)

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