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CHEM 46 > Mixed > Flashcards

Mixed Flashcards

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1
Q

True or False: Glycolysis occurs in the mitochondria of the cell.

A

False. It occurs in the cytoplasm of the cell

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2
Q

Which enzyme catalyzes the first step of glycolysis?

a) Hexokinase
b) Phosphofructokinase
c) Pyruvate kinase
d) Enolase

A

a) Hexokinase

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3
Q

Which of the following is the end product of glycolysis?

a) Lactate
b) Acetyl-CoA
c) Pyruvate
d) Citrate

A

c) Pyruvate

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4
Q

In glycolysis, which molecule is directly converted into fructose-1,6-bisphosphate?

a) Glucose
b) Glucose-6-phosphate
c) Fructose-6-phosphate
d) Fructose-1-phosphate

A

c) Fructose-6-phosphate

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5
Q

True or False: The conversion of phosphoenolpyruvate (PEP) to pyruvate generates ATP.

A

True

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6
Q

True or False: Gluconeogenesis is the process of synthesizing glucose from non-carbohydrate precursors.

A

True

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7
Q

Which enzyme is involved in the first step of gluconeogenesis?

a) Pyruvate carboxylase
b) Phosphoenolpyruvate carboxykinase
c) Fructose-1,6-bisphosphatase
d) Glucose-6-phosphatase

A

a) Pyruvate carboxylase

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8
Q

What is the intermediate molecule formed when pyruvate is converted to phosphoenolpyruvate (PEP) in gluconeogenesis?

a) Oxaloacetate
b) Malate
c) Lactate
d) Glycerol

A

a) Oxaloacetate

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9
Q

True or False: Gluconeogenesis mainly occurs in the liver and kidneys.

A

True

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10
Q

Which enzyme catalyzes the final step of gluconeogenesis, converting glucose-6-phosphate to glucose?

a) Hexokinase
b) Glucokinase
c) Glucose-6-phosphatase
d) Phosphofructokinase

A

c) Glucose-6-phosphatase

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11
Q

True or False: ATP acts as an allosteric inhibitor of phosphofructokinase in glycolysis.

A

True

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12
Q

Which of the following is an allosteric activator of phosphofructokinase?

a) ATP
b) Citrate
c) AMP
d) NADH

A

c) AMP

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13
Q

What effect does fructose-2,6-bisphosphate have on glycolysis?

a) Inhibits glycolysis
b) Activates gluconeogenesis
c) Activates glycolysis
d) No effect

A

c) Activates glycolysis

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14
Q

True or False: Pyruvate kinase activity is regulated by phosphorylation in liver cells.

A

True

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15
Q

Which molecule inhibits pyruvate kinase by promoting its phosphorylation?

a) Glucose
b) Glucagon
c) Insulin
d) Fructose-1,6-bisphosphate

A

b) Glucagon

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16
Q

Which cofactor is essential for the activity of pyruvate carboxylase in gluconeogenesis?

a) NAD+
b) FAD
c) TPP
d) Biotin

A

d) Biotin

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17
Q

True or False: Transketolase requires TPP as a cofactor.

A

True

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18
Q

What is the role of biotin in gluconeogenesis?

a) Acts as an electron carrier
b) Transfers a carbon dioxide group
c) Phosphorylates glucose
d) Converts pyruvate to lactate

A

b) Transfers a carbon dioxide group

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19
Q

Which enzyme uses NAD+ as a cofactor in the conversion of lactate to pyruvate?

a) Lactate dehydrogenase
b) Pyruvate kinase
c) Hexokinase
d) Aldolase

A

a) Lactate dehydrogenase

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20
Q

True or False: Phosphofructokinase-2 (PFK-2) and fructose-2,6-bisphosphatase are two separate enzymes.

A

False

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21
Q

True or False: Deficiency in vitamin C leads to scurvy.

A

True

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22
Q

Which vitamin deficiency causes beriberi?

a) Vitamin B1 (Thiamine)
b) Vitamin B2 (Riboflavin)
c) Vitamin B3 (Niacin)
d) Vitamin B12 (Cobalamin)

A

a) Vitamin B1 (Thiamine)

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23
Q

Which disease is caused by a lack of niacin (Vitamin B3)?

a) Pellagra
b) Rickets
c) Scurvy
d) Beriberi

A

a) Pellagra

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24
Q

True or False: Vitamin D deficiency can lead to rickets in children.

A

True

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25
Q

Which vitamin is crucial for blood clotting?

a) Vitamin A
b) Vitamin D
c) Vitamin E
d) Vitamin K

A

d) Vitamin K

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26
Q

True or False: Galactosemia is due to a deficiency in the enzyme galactose-1-phosphate uridylyltransferase.

A

True

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27
Q

What is the main consequence of fructose intolerance?

a) Accumulation of fructose in blood
b) Accumulation of fructose-1-phosphate
c) Increased glycogen storage
d) Enhanced glycolysis

A

b) Accumulation of fructose-1-phosphate

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28
Q

True or False: High intake of fructose can lead to increased fat synthesis.

A

True

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29
Q

Which enzyme deficiency is linked to lactose intolerance?

a) Sucrase
b) Lactase
c) Maltase
d) Isomaltase

A

b) Lactase

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30
Q

True or False: Deficiency of glucose-6-phosphate dehydrogenase (G6PD) can lead to hemolytic anemia.

A

True

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31
Q

Which enzyme converts fructose-6-phosphate to fructose-1,6-bisphosphate in glycolysis?

a) Aldolase
b) Hexokinase
c) Phosphofructokinase
d) Triose phosphate isomerase

A

c) Phosphofructokinase

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32
Q

True or False: The enzyme glucose-6-phosphate dehydrogenase (G6PD) is part of the glycolytic pathway.

A

False

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33
Q

Which enzyme is responsible for the isomerization of glucose-6-phosphate to fructose-6-phosphate?

a) Hexokinase
b) Phosphoglucose isomerase
c) Phosphofructokinase
d) Aldolase

A

b) Phosphoglucose isomerase

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34
Q

True or False: Pyruvate dehydrogenase complex requires thiamine pyrophosphate (TPP) as a cofactor.

A

True

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35
Q

Which enzyme in glycolysis directly produces ATP by substrate-level phosphorylation?

a) Hexokinase
b) Phosphofructokinase
c) Pyruvate kinase
d) Phosphoglycerate kinase

A

c) Pyruvate kinase

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36
Q

True or False: The Cori cycle involves the interconversion of lactate and glucose between muscle and liver.

A

True

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37
Q

What is the primary purpose of the pentose phosphate pathway?

a) Generate ATP
b) Produce NADPH and ribose-5-phosphate
c) Synthesize amino acids
d) Store glucose as glycogen

A

b) Produce NADPH and ribose-5-phosphate

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38
Q

True or False: Acetyl-CoA is a central metabolite that links glycolysis and the citric acid cycle.

A

True

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39
Q

Which pathway is directly linked to the detoxification of reactive oxygen species?

a) Glycolysis
b) Gluconeogenesis
c) Pentose phosphate pathway
d) Urea cycle

A

c) Pentose phosphate pathway

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40
Q

True or False: Fatty acid synthesis occurs primarily in the mitochondria.

A

True

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41
Q

Which of the following is an energy currency molecule in cells?

a) Glucose
b) ATP
c) NAD+
d) Pyruvate

A

b) ATP

42
Q

True or False: NADH generated in glycolysis can be used for ATP production via oxidative phosphorylation.

A

True

43
Q

Which of the following is an electron carrier molecule?

a) ATP
b) NADH
c) FADH2
d) Both b and c

A

d) Both b and c

44
Q

True or False: The conversion of pyruvate to acetyl-CoA by pyruvate dehydrogenase is reversible.

A

False

45
Q

During vigorous exercise, which molecule accumulates in muscles leading to fatigue?

a) Lactate
b) Glucose
c) Acetyl-CoA
d) Fructose

A

a) Lactate

46
Q

True or False: Fatty acids are stored as triacylglycerols in the body.

A

True

47
Q

Which of the following is a function of fatty acids?
A) Serve as neurotransmitters
B) Form phospholipids and glycolipids
C) Act as simple sugars
D) Serve as DNA building blocks

A

B) Form phospholipids and glycolipids

48
Q

True or False: Fatty acids yield more energy per gram than carbohydrates and proteins.

A

True

49
Q

What is the main product of fatty acid degradation?
A) Glucose
B) Acetyl CoA
C) Glycerol
D) Pyruvate

A

B) Acetyl CoA

50
Q

True or False: The first step in fatty acid catabolism is their activation and transport into the mitochondria.

A

False (The first step is lipid mobilization)

51
Q

Which enzyme is responsible for the hydrolysis of triacylglycerols in the stomach and small intestine?
A) Lipase
B) Protease
C) Amylase
D) Lactase

A

A) Lipase

52
Q

True or False: Glycerol is transported to the liver for further metabolism.

A

True

53
Q

What is the role of glycerol kinase in the metabolism of glycerol?
A) Converts glycerol to L-Glycerol-3P
B) Converts glycerol to glucose
C) Converts glycerol to DHAP
D) Converts glycerol to ATP

A

A) Converts glycerol to L-Glycerol-3P

54
Q

True or False: Fatty acids are activated in the mitochondrial matrix.

A

False. Activated in the cytoplasm

55
Q

Which coenzyme is required for the activation of fatty acids?
A) NAD+
B) Coenzyme A (CoA)
C) FAD
D) ATP

A

B) Coenzyme A (CoA)

56
Q

True or False: The oxidation of acyl CoA to enoyl CoA is the first reaction in each round of fatty acid degradation.

A

True

57
Q

What enzyme catalyzes the conversion of acyl CoA to enoyl CoA?
A) Enoyl-CoA hydratase
B) Acyl CoA dehydrogenase
C) β-Ketoacyl-CoA thiolase
D) L-3-Hydroxyacyl-CoA dehydrogenase

A

B) Acyl CoA dehydrogenase

58
Q

True or False: Acetyl CoA enters the citric acid cycle for further energy production.

A

True

59
Q

Which molecule is not a product of the complete oxidation of fatty acids?
A) Acetyl CoA
B) FADH2
C) NADH
D) Glucose

A

D) Glucose

60
Q

True or False: The degradation of palmitoyl CoA requires seven reaction cycles.

A

True

61
Q

What is the total ATP yield from the complete oxidation of palmitate?
A) 106 ATP
B) 104 ATP
C) 108 ATP
D) 110 ATP

A

A) 106 ATP

62
Q

True or False: Unsaturated fatty acids yield the same amount of ATP as saturated fatty acids.

A

False

63
Q

Which enzyme is responsible for converting cis-A3-enoyl CoA to trans-A2-enoyl CoA?
A) Enoyl-CoA hydratase
B) Cis-A3-enoyl CoA isomerase
C) Acyl CoA dehydrogenase
D) β-Ketoacyl-CoA thiolase

A

B) Cis-A3-enoyl CoA isomerase

64
Q

True or False: Acetyl CoA can be used to synthesize glucose in the gluconeogenesis pathway.

A

False. While some of the products of Acetyl-CoA metabolism can feed into gluconeogenesis, Acetyl-CoA itself cannot be directly converted back to glucose. The reason is that the conversion of pyruvate to Acetyl-CoA (by pyruvate dehydrogenase) is an irreversible step.

65
Q

What condition is characterized by very high levels of ketone bodies leading to acidosis?
A) Hypoglycemia
B) Diabetes ketoacidosis
C) Hyperlipidemia
D) Glycogen storage disease

A

B) Diabetes ketoacidosis. Very high levels of ketone bodies causing acidosis is the hallmark of diabetic ketoacidosis.

A) This is low blood sugar, the opposite of what causes ketone body production.
C) This is high levels of fats (lipids) in the blood. While it can be a factor in some metabolic conditions, it doesn’t directly cause the high ketone levels seen in DKA.
D) These are genetic disorders affecting how the body stores and uses glycogen (stored glucose). They don’t primarily lead to excessive ketone production.

66
Q

True or False: Ketone bodies include acetoacetate and D-3-hydroxybutyrate.

A

True

67
Q

Which of the following enzymes is not involved in β-oxidation?
A) Acyl CoA dehydrogenase
B) Enoyl-CoA hydratase
C) L-3-Hydroxyacyl-CoA dehydrogenase
D) Glycerol kinase

A

D) Glycerol kinase. Involved in glycerol metabolism, not fatty acid breakdown.

A) This enzyme catalyzes the first step of β-oxidation, removing hydrogen atoms from the fatty acid chain.
B) This enzyme adds water across a double bond created in the previous step.
C) This enzyme oxidizes the hydroxyl group introduced in the previous step, generating NADH.

68
Q

True or False: Acetyl CoA is a common intermediate in both fatty acid degradation and the citric acid cycle.

A

True

69
Q

What is the function of carnitine in fatty acid metabolism?
A) Activates fatty acids in the cytoplasm
B) Transports fatty acids into the mitochondria
C) Converts fatty acids to glucose
D) Breaks down fatty acids into acetyl CoA

A

B) Transports fatty acids into the mitochondria. Carnitine acts as a transporter, ensuring fatty acids reach the location where they can be broken down for energy.

A) In the cytoplasm, fatty acids are “activated” by attaching to Coenzyme A, forming fatty acyl-CoA.
C) Carnitine then steps in and temporarily binds to the fatty acyl-CoA. This allows the fatty acyl-carnitine complex to pass through the mitochondrial membrane.
D) Once inside the mitochondria, the fatty acyl-CoA is released from carnitine and can now undergo β-oxidation to produce energy.

70
Q

True or False: The liver is the primary site for ketone body production.

A

True

71
Q

Which ketone body can be directly utilized as an energy source by the brain?
A) Acetone
B) Acetoacetate
C) D-3-hydroxybutyrate
D) Both B and C

A

D) Both B and C

72
Q

True or False: In prolonged fasting, muscle protein is used for gluconeogenesis.

A

True

73
Q

What molecule is a key regulatory point for both glycolysis and gluconeogenesis?
A) Citrate
B) Acetyl CoA
C) Fructose 2,6-bisphosphate
D) ATP

A

C) Fructose 2,6-bisphosphate

74
Q

True or False: Insulin promotes the uptake of glucose by cells and the storage of fat.

A

True

75
Q

Which of the following is a symptom of ketoacidosis?
A) Low blood glucose levels
B) High blood glucose levels
C) Low ketone body levels
D) High oxygen levels

A

B) High blood glucose levels

76
Q

True or False: Fatty acid synthesis primarily occurs in the mitochondria.

A

False (It occurs in the cytoplasm)

77
Q

What is the initial substrate for fatty acid synthesis?
A) Glucose
B) Acetyl CoA
C) Pyruvate
D) Malonyl CoA

A

B) Acetyl CoA

78
Q

True or False: Malonyl CoA is formed by the carboxylation of acetyl CoA.

A

True

79
Q

Which enzyme catalyzes the rate-limiting step in fatty acid synthesis?
A) Acetyl CoA carboxylase
B) Fatty acid synthase
C) Malonyl CoA decarboxylase
D) Citrate synthase

A

A) Acetyl CoA carboxylase. Acetyl CoA carboxylase is the rate-limiting enzyme in fatty acid synthesis because it catalyzes the first committed, irreversible, and highly regulated step, controlling the flow of precursors into the pathway.

B) This is a large enzyme complex that carries out multiple steps after malonyl CoA is formed. While important, it’s not the rate-limiting enzyme.
C) This enzyme works in the opposite direction, breaking down malonyl CoA.
D) This enzyme is part of the citric acid cycle, which is connected to but not directly involved in the rate-limiting step of fatty acid synthesis.

80
Q

True or False: Fatty acid synthase is a multi-enzyme complex.

A

True

81
Q

What coenzyme is essential for fatty acid synthesis?
A) NAD+
B) NADPH
C) FADH2
D) ATP

A

B) NADPH. This acts as the primary electron donor in fatty acid synthesis. It provides the reducing power needed to reduce the carbonyl groups (C=O) to hydroxyl groups (C-OH) during the elongation steps.

A) NAD+ is an electron carrier involved in catabolic processes (breaking down molecules), where it accepts electrons.
C) FADH2 is another electron carrier, primarily involved in the electron transport chain and some other metabolic reactions.
D) ATP is the primary energy currency of the cell. While ATP provides the energy for fatty acid synthesis, it doesn’t directly act as an electron donor like NADPH.

82
Q

True or False: Palmitate is the final product of the fatty acid synthase complex.

A

True

83
Q

Which molecule is not involved in the elongation phase of fatty acid synthesis?
A) Acetyl CoA
B) Malonyl CoA
C) NADPH
D) FADH2

A

D) FADH2. Not directly involved in the elongation phase of fatty acid synthesis. Its primary role is in other metabolic processes, like the electron transport chain, where it helps generate ATP.

A) This is the two-carbon donor, providing the building blocks for chain extension.
B) It’s involved initially to prime the fatty acid synthase complex but doesn’t directly participate in subsequent elongation cycles.
C) NADPH provides the reducing power (electrons) needed to reduce the carbonyl groups during elongation.

84
Q

True or False: Elongation of fatty acids occurs by the addition of two-carbon units.

A

True

85
Q

Which enzyme catalyzes the formation of double bonds in fatty acids?
A) Fatty acid desaturase
B) Fatty acid synthase
C) Acetyl CoA carboxylase
D) Citrate synthase

A

A) Fatty acid desaturase

86
Q

True or False: Linoleic and linolenic acids are essential fatty acids.

A

True

87
Q

Which fatty acid is not synthesized by the human body?
A) Palmitic acid
B) Stearic acid
C) Linoleic acid
D) Oleic acid

A

C) Linoleic acid. An essential fatty acid that the human body cannot synthesize and must be obtained from dietary sources.

A) This is a saturated fatty acid that our bodies can synthesize.
B) This is another saturated fatty acid that we can produce.
D) This is a monounsaturated fatty acid that our bodies can make from stearic acid.

88
Q

True or False: Citrate can be transported out of the mitochondria for fatty acid synthesis.

A

True

89
Q

What role does biotin play in fatty acid synthesis?
A) Activates acetyl CoA
B) Acts as a coenzyme for carboxylation reactions
C) Transports acetyl CoA into the mitochondria
D) Acts as a reducing agent

A

B) Acts as a coenzyme for carboxylation reactions. Acetyl-CoA carboxylase uses biotin to add a carboxyl group to acetyl CoA, converting it into malonyl CoA.

A) Biotin doesn’t directly “activate” acetyl CoA. Instead, it enables the carboxylation reaction that converts acetyl CoA into malonyl CoA.
C) Acetyl CoA is transported into the mitochondria for energy production (the citric acid cycle), but biotin is not involved in this transport process. A separate molecule called carnitine plays a role in that.
D) Biotin doesn’t donate electrons like reducing agents (e.g., NADPH). Its role is specifically in facilitating carboxylation reactions.

90
Q

True or False: Fatty acids can be converted into glucose in the human body.

A

False

91
Q

Which process is not part of lipid catabolism?
A) Lipolysis
B) β-Oxidation
C) Ketogenesis
D) Lipogenesis

A

D) Lipogenesis

92
Q

True or False: Fatty acid degradation is also known as β-oxidation.

A

True

93
Q

What is the final product of odd-chain fatty acid β-oxidation?
A) Acetyl CoA
B) Propionyl CoA
C) Malonyl CoA
D) Butyryl CoA

A

B) Propionyl CoA

94
Q

True or False: Propionyl CoA can be converted into succinyl CoA, which enters the citric acid cycle.

A

True

95
Q

Which intermediate is unique to odd-chain fatty acid oxidation?
A) Acetyl CoA
B) Succinyl CoA
C) Propionyl CoA
D) Malonyl CoA

A

C) Propionyl CoA

96
Q

What is the primary proteolytic enzyme in the stomach?

A

Pepsin

97
Q

True or False: The digestion of proteins begins in the stomach.

A

True

98
Q

Which enzyme marks unneeded or damaged proteins for destruction?
A) Pepsin
B) Ubiquitin-conjugating enzyme
C) Aminopeptidase N
D) Secretin

A

B) Ubiquitin-conjugating enzyme. Essential for marking unneeded or damaged proteins with ubiquitin, effectively targeting them for destruction by the proteasome.

A) Pepsin is a digestive enzyme found in the stomach. It breaks down proteins in food, not cellular proteins that need to be degraded.
C) This enzyme is involved in trimming amino acids from the ends of proteins, but it doesn’t play a role in targeting proteins for destruction.
D) Secretin is a hormone that regulates secretions in the digestive system and is not involved in protein degradation.

99
Q

True or False: Proteasome is an ATP-independent complex.

A

True

100
Q

Which hormone regulates gastric juices in the stomach?
A) Insulin
B) Secretin
C) Glucagon
D) Pepsin

A

B) Secretin

CHEM 46 (15 decks)

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