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Biochemisty Main > Biochem - LE5 (2024) > Flashcards

Biochem - LE5 (2024) Flashcards

1
Q
  1. Which active lipase acts on diacylglycerol in the lipid droplet?
    A. Adipose triacylglycerol lipase
    B. Hormone sensitive lipase

C. Monoacylglycerol lipase
D. Colipase

A

Hormone sensitive lipase

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2
Q
  1. Which is the major pathway of the oxidation process?
    A. Mitochondrial beta
    B. Alpha
    C. Omega
    D. Peroxisomal
A

Mitochondrial beta

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3
Q
  1. Beta oxidation occurs in almost all tissues
    EXCEPT:
    A. Erythrocytes
    B. Hepatocytes
    C. Muscle cells
    D. Myocardiocytes
A

Erythrocytes

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4
Q
  1. What molecule activates fatty acids prior to transport into the matrix?
    A. Carnitine
    B. Coenzyme A
    C. Coenzyme Q
    D. Acyl carrier protein
A

Coenzyme A

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5
Q
  1. How many moles of high energy phosphate compounds are hydrolysed in the activation of fatty acids?

A. 1
B. 2
C. 3

D. 4

A

2

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6
Q
  1. What drives the activation reaction of fatty acids to completion?
    A. Formation of the acyl adenylate moiety
    B. The release of the AMP

C. Hydrolysis of the PPi by inorganic phosphatase

D. Nucleophilic attack by the sulphur atom of CoA

A

Hydrolysis of the PPi by inorganic phosphatase

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7
Q
  1. Which protein transports the palmitoyl carnitine inside the matrix?
    A. Carnitine acyl carnitine translocase
    B. Tricarboxylate translocase
    C. Monocarboxylate translocase
    D. Dicarboxylate translocase
A

Carnitine acyl carnitine translocase

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8
Q
  1. What are the four reactions, in the order of occurrence, which are carried out every time a two carbon moiety is removed from a fatty acid being oxidized?

A. Cleavage, hydration, oxidation, oxidation

B. Oxidation, cleavage, oxidation, hydration

C. Oxidation, hydration, oxidation, cleavage
D. Hydration, oxidation, cleavage, oxidation

A

Oxidation, hydration, oxidation, cleavage

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9
Q
  1. What complex of the ETC accepts the electrons and protons coming from the first reaction of beta oxidation?

A. NADH-CoQ oxidoreductase
B. ETFP-CoQ oxidoreductase
C. Cytochrome c oxidase
D. Cytochrome oxidase

A

B. ETFP-CoQ oxidoreductase

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10
Q
  1. Which enzymes catalyze the third reaction of beta oxidation?
    A. Acyl CoA dehydrogenase
    B. Thiolase
    C. Enoly CoA hydratase
    D. 3-L-hydroxyacylCoA dehydrogenase
A

3-L-hydroxyacylCoA dehydrogenase

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11
Q
  1. How many ATPs does the second reaction of beta oxidation generates after transferring its electrons and protons to the ETC?

A. 2
B. 3
C. 4
D. 5

A

3

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12
Q
  1. How many cycles/spirals would a 16 carbon saturated fatty acid undergo in beta oxidation releasing the acetyl CoA moieties?

A. 5
B. 6
C. 7

D. 8

A

7

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13
Q
  1. How many ATPs are generated from all the acetyl CoA moieties released from beta-oxidation of palmitic acid?

A. 90
B. 93
C. 96
D. 98

A

108

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14
Q
  1. What is the product of the last cycle/spiral of beta oxidation of a 17 carbon saturated fatty acid aside from acetyl CoA?

A. Acetyl CoA
B. Isobutyryl CoA
C. Propionyl CoA
D. Valeryl CoA

A

Propionyl CoA

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15
Q
  1. To what intermediate of the TCA cycle does the product of the last cycle/spiral of beta-oxidation of odd-chain fatty acid enter?

A. Fumarate
B. Succinyl-CoA
C. Succinate
D. Malate

A

Succinyl-CoA

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16
Q
  1. What additional enzyme is used in the beta oxidation of a monounsaturated fatty acid?
    A. ∆3∆2-enoyl CoA isomerase
    B. 2,4-dienoyl CoA-reductase
    C. Enoyl CoA-reductase
    D. Acyl CoA dehydrogenase
A

A. ∆3∆2-enoyl CoA isomerase

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17
Q
  1. How many ATP less would be derived from oxidation of a monounsaturated fatty acid compared with the oxidation of a saturated fatty acid having the same number of carbons?
    A. 4
    B. 3
    C. 2
    D. 1
A

2

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18
Q
  1. Which oxidation process is used to degrade very long chain fatty acids?
    A. Mitochondrial beta
    B. Alpha
    C. Omega
    D. Peroxisomal
A

D. Peroxisomal

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19
Q
  1. How would the products of oxidation of VLCFA generate energy in the form of ATP?

A. Have to be transported to the mitochondrial matrix

B. Thru the glycolytic pathway
C. Metabolized thru the alpha oxidation

D. Degraded via the omega oxidation

A

Have to be transported to the mitochondrial matrix

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20
Q
  1. More ATPs are formed per cycle/spiral thru mitochondrial beta oxidation than thru oxidation of VLCFA, by how many?

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

A

2

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21
Q
  1. Which of the following characterize arachidonic acid?
    A. ω-3 polyunsaturated
    B. Contains C18
    C. Cis configurations
    D. 4 double bonds at 5, 8, 12, 14
A

Cis configurations

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22
Q
  1. Eicosanoids are not construed by:
    A. Found in structural lipids
    B. Synthesized from ω-3 FAs

C. Synthesized from ω-6 FAs
D. Synthesized from monounsaturated FAs

A

Synthesized from ω-3 FAs

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23
Q
  1. Classic eicosanoids:

A. Contains 2 double bonds and 4 double bonds
B. Derived from eicosapentaenoic acid
C. ω-6 series derived from AA
D. Requires phospholipase A

A

ω-6 series derived from AA

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24
Q
  1. Prostanoids and leukotrienes derived from eicosapentaenoic acids:
    A. Prostanoids have 3 double bonds
    B. Leukotrienes have 4 double bonds
    C. Prostanoids have 2 double bonds
    D. Leukotrienes have 6 double bonds
A

Leukotrienes have 4 double bonds

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25
Q
  1. Prostanoids and leukotrienes derived from arachidonic acids:

A. Prostanoidds have 3 double bonds
B. Leukotrienes have 4 double bonds
C. Prostanoids have 5 double bonds
D. Leukotrienes have 6 double bonds

A

Leukotrienes have 4 double bonds

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26
Q
  1. The first reaction by cyclooxygenase on Arachidonic acid, in the cyclooxygenase pathway, except:

A. Is a committed step
B. Creates a cyclopentate ring
C. Addition of 2 double bonds
D. Forms an endoperoxide ring

A

Creates a cyclopentate ring

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27
Q
  1. Committed step in the cyclooxygenase pathway:

A. Protsglandin endoperoxidase synthase to produce PGH2
B. Cyclooxygenase to produce PGH2

C. Prostaglandin endoperoxide synthase to produce PGG2
D. Cyclooxygenase to produce AA

A

Protsglandin endoperoxidase synthase to produce PGH2

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28
Q
  1. Formed by catalysed non oxidative arrangements:
    A. PGE2
    B. PGF2
    C. PGG2
    D. PGH2
A

PGF2

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29
Q
  1. Formed by reductase from PGH2
    A. PGD2
    B. PGE2

C. PGF2
D. PGG2

A

PGF2

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30
Q
  1. Formed by prostacyclin synthase
    A. PGH2
    B. PGI2
    C. PGF2
    D. PGD2
A

PGI2

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31
Q
  1. Converts arachidonic acid to 5-hydroperoxyeicosatetraenoic acid
    A. 15 lipoxygenase
    B. 5 lipoxygenase
    C. 12 lipoxygenase
    D. Glutathione-dependent peroxidases
A

5 lipoxygenase

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32
Q
  1. 5-hydroxyeicosatetraenoic acid is formed by
    A. 15 lipoxygenase
    B. 5 lipoxygenase
    C. 12 lipoxygenase

D. Glutathione-dependent peroxidases

A

Glutathione-dependent peroxidases

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33
Q
  1. LTA4 is formed by LTA synthase from:
    A. 5 HPETE
    B. 5 HETE
    C. 5 LO
    D. ALOX 5
A

5 LO

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34
Q
  1. Attaches sulphur of cysteine’s thio (SH) group in the tripeptide glutamate-cysteine-glycine to carbon 6 of LTA4:

A. 5 LO
B. ALOX 5
C. MGST 2
D. LTA synthase

A

MGST 2

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35
Q
  1. Glutamic acid is removed from LTC4 to form LTD4 by:
    A. Gamma-glutamyltransferase
    B. Dipeptidase
    C. Hydrolase
    D. Synthase
A

Gamma-glutamyltransferase

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36
Q
  1. Glycine is removed from LTD4 to form LTE4 by:
    A. Gamma-glutamyltransferase
    B. Dipeptidase
    C. Hydrolase
    D. Synthase
A

Dipeptidase

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37
Q
  1. Leukotrienes:
    A. Increase pain
    B. Chemotaxis
    C. Prothrombotic
    D. Bronchoconstriction
A

Bronchoconstriction

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38
Q
  1. Prostacyclins
    A. Vasodilation
    B. Prothrombotic
    C. Increase temperature
    D. Bronchoconstriction
A

Vasodilation

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39
Q
  1. Prostaglandins
    A. Vasodilation
    B. Prothrombotic
    C. Increase temperature
    D. Bronchoconstriction
A

Vasodilation

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40
Q
  1. Effect of thromboxanes EXCEPT:
    A. Vasodilation
    B. Prothrombotic
    C. Vascular permeability
    D. Bronchoconstriction
A

Vasodilation

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41
Q
  1. Cholesterol is transported via:
    A. Phospholipids
    B. Lipoproteins
    C. Phosphoproteins
    D. Sphingolipids
A

Lipoproteins

42
Q
  1. Cholesterol is the precursor for the following
    EXCEPT:
    A. Sex hormones
    B. Vitamin D
    C. Vitamin A
    D. Bile acids
43
Q
  1. Synthesis of cholesterol occurs in the cytosol and in:
    A. Golgi apparatus
    B. Lysosome
    C. Endoplasmic reticulum
    D. Mitochondria
A

Endoplasmic reticulum

44
Q
  1. Free cholesterol is removed from tissues and transported to the liver by:

A. Chylomicrons
B. HDL
C. LD
D. VLDL

45
Q
  1. The enzyme that catalyzes the rate limiting step in cholesterol synthesis:
    A. Thiolase
    B. HMG CoA synthase
    C. HMG CoA reductase
    D. Isomerase
A

HMG CoA reductase

46
Q
  1. Cholesterol is synthesized in:

A. Liver and intestines only
B. RBCs only
C. All nucleated cells
D. A and B

A

All nucleated cells

47
Q
  1. The structure of cholesterol is a cyclopentano__phenanthrene ring
    A. Dihydro
    B. Perhydro
    C. Pentahydro
    D. Cyclohydro
48
Q
  1. In cholesterol structure, the hydroxyl group is located at the:
    A. C3
    B. C5
    C. C6
    D. C17
49
Q
  1. Esterification to form cholesterol esters occurs at the:
    A. C3
    B. C5
    C. C6
    D. C17
50
Q
  1. The formation of isoprenoid units from mevalonate requires how many ATP?

A. None
B. 1
C. 2
D. 3

51
Q
  1. HMG-CoA is a ___ compound:
    A. 5-carbon
    B. 6-carbon
    C. 10-carbon
    D. 15-carbon
52
Q
  1. Cyclization of squalene give rise to the parent sterol:
    A. Ergocalciferol
    B. Lanosterol
    C. Cholecalciferol
    D. Cortisol
A

Lanosterol

53
Q
  1. Formation of squalene requires a total of:
    A. 20 ATP
    B. 24 ATP
    C. 18 ATP
    D. 36 ATP
54
Q
  1. HMG CoA reductase is active in the
    A. Phosphorylated form
    B. Dephosphorylated form
    C. Both
    D. None
A

Dephosphorylated form

55
Q
  1. Which hormone/s downregulates the expression of the gene for HMG CoA reductase?
    A. Insulin
    B. Glucagon
    C. Thyroxine
    D. A and C
56
Q
  1. The statin drugs are structural analogs of HMG CoA and are ___ inhibitors of HMG CoA reductase

A. Nonreversible, competitive
B. Reversible, noncompetitive
C. Nonreversible, noncompetitive
D. Reversible, competitive

A

Reversible, competitive

57
Q
  1. This lipoprotein contains the highest TAG
    A. LDL
    B. HDL
    C. VLDL
    D. Chylomicrons
A

Chylomicrons

58
Q
  1. LDL is taken up by the cell via:
    A. Transport protein
    B. Endocytosis
    C. Ligand channel
    D. Proton pump
A

Endocytosis

59
Q
  1. True of cholesterol excretion except:

A. Cholesterol is metabolized to CO2 and H2O
B. Small percentage excreted in the feces
C. Converted to bile acid and bile salts
D. None

A

Cholesterol is metabolized to CO2 and H2O

60
Q
  1. 7α-hydroxylation of cholesterol requires NADPH, cytochrome P450 and:
    A. Cu
    B. Vitamin C

C. Oxygen
D. Zn

61
Q
  1. Which of the following statements regarding fatty acid synthesis is/are FALSE?
    A. It takes place in the mitochondrial matrix

B. Synthesis intermediates are covalently linked to Acyl Carrier Protein

C. Its rate-limiting enzyme is acetyl-CoA carboxylase

D. All of the above

A

It takes place in the mitochondrial matrix

62
Q
  1. What are the four repeating steps in fatty acid synthesis in correct order (from most oxidized to least oxidized substrate)?

A. Condensation, reduction, dehydration, reduction
B. Oxidation, hydration, oxidation, lysis

C. Reduction, dehydration, reduction, dehydration

D. Condensation, dehydration, reduction, condensation

A

Condensation, reduction, dehydration, reduction

63
Q
  1. Which of the following acts as a source of reducing equivalents for fatty acid synthesis?

A. NADH
B. NADPH
C. Glutathione peroxidase

D. Fatty acid synthase

64
Q
  1. Fatty acid synthesis is synthesized ___

carbon(s) at a time for each cycle with the final product being ___.
A. 4, oleic acid
B. 1, acetoacetyl-CoA
C. 2, palmitic acid
D. 8, palmitate

A

2, palmitic acid

65
Q
  1. Which carbon(s) is/are initially added to the structure of a fatty acid?
    A. Methyl end carbon
    B. Carboxyl end carbon
    C. Unsaturated carbons
    D. Chiral carbon
A

Methyl end carbon

66
Q
  1. Which of the following activates fatty acid synthesis?

A. Insulin
B. Citrate
C. Long chain fatty acyl-CoA
D. A and B only

A

A and B only

67
Q
  1. The rate-limiting enzyme of fatty acid synthesis is inhibited by:
    A. Cyclic AMP
    B. Dephosphorylation
    C. Insulin
    D. All of the above
A

Cyclic AMP

68
Q
  1. Fatty acid synthesis from its 2-carbon CoA precursor needs to be transferred to the cytosol from the mitochondria. This is done by converting the precursor to _____.

A. Malate

B. Citrate
C. Oxaloacetate
D. Acetoacetyl CoA

69
Q
  1. The rate-limiting enzyme of fatty acid synthesis is activated by _____ and switched off by
    _____.
    A. Phosphorylation, dephosphorylation
    B. Dephosphorylation, phosphorylation
    C. Acetylation, deacetylation
    D. Deacytelation, acetylation
A

Dephosphorylation, phosphorylation

70
Q
  1. The rate-limiting enzyme of fatty acid synthesis uses this as a carbon dioxide carrier:
    A. Biotin
    B. Pyridoxine
    C. NADPH
    D. Folate
71
Q
  1. Conversion of malate to oxaloacetate:
    A. Pentose phosphate pathway
    B. Citric acid cycle
    C. Pyruvate dehydrogenase complex
    D. Fatty acid synthase complex
    E. Acetyl-CoA carboxylase
A

Citric acid cycle

72
Q
  1. Formation of Acetyl-CoA from glucose:
    A. Pentose phosphate pathway
    B. Citric acid cycle
    C. Pyruvate dehydrogenase complex
    D. Fatty acid synthase complex
    E. Acetyl-CoA carboxylase
A

Pyruvate dehydrogenase complex

73
Q
  1. Main source of reducing equivalents for fatty acid synthesis:
    A. Pentose phosphate pathway
    B. Citric acid cycle
    C. Pyruvate dehydrogenase complex
    D. Fatty acid synthase complex
    E. Acetyl-CoA carboxylase
A

Pentose phosphate pathway

74
Q
  1. Enoyl reductase
    A. Pentose phosphate pathway
    B. Citric acid cycle
    C. Pyruvate dehydrogenase complex
    D. Fatty acid synthase complex
    E. Acetyl-CoA carboxylase
A

Fatty acid synthase complex

75
Q
  1. Production of malonyl-CoA:
    A. Pentose phosphate pathway
    B. Citric acid cycle
    C. Pyruvate dehydrogenase complex
    D. Fatty acid synthase complex
    E. Acetyl-CoA carboxylase
A

Acetyl-CoA carboxylase

76
Q
  1. Complex amino alcohol plus fatty acid, which is abundant in cell membranes that are specialized to form lipid rafts:

A. Triacylglycerol
B. Glycerophospholipids
C. Ether glycerolipids
D. Sphingomyelin
E. Glycolipids

A

Sphingomyelin

77
Q
  1. Mostly stored as energy reserve in adipose tissue and liver:
    A. Triacylglycerol
    B. Glycerophospholipids
    C. Ether glycerolipids
    D. Sphingomyelin
    E. Glycolipids
A

Triacylglycerol

78
Q
  1. Cerebrosides and globosides:
    A. Triacylglycerol
    B. Glycerophospholipids
    C. Ether glycerolipids

D. Sphingomyelin
E. Glycolipids

A

Glycolipids

79
Q
  1. Plasmalogens:
    A. Triacylglycerol
    B. Glycerophospholipids
    C. Ether glycerolipids
    D. Sphingomyelin
    E. Glycolipids
A

Ether glycerolipids

80
Q
  1. Lung surfactant:
    A. Triacylglycerol
    B. Glycerophospholipids
    C. Ether glycerolipids
    D. Sphingomyelin

E. Glycolipids

A

Glycerophospholipids

81
Q
  1. A 51-year old male patient presents with intense redness, heat, and pain over his left metatarsophalangeal joint of the big toe. Fluid from this joint shows bifringent crystals. This disease caused by the degradation of an excessive amount of which of the following?

A. Guanine
B. Cytosine
C. Uracil
D. Ribose-5-phosphate

82
Q
  1. A researcher wants to develop a method of labelling purines with 15N for use in future spectroscopic studies. Purine synthesis will be done in a test tube using only the enzymes necessary to synthesize purines via the de novo pathway. Which starting materials should be labelled with the heavy nitrogen in order to maximize 15N incorporation into purines?

A. Aspartate, glycine, and N5-formimino tetrahydrofolate
B. Asparagine, glycine, and glutamine
C. Asparagine, glutamate, and glutamine
D. Aspartate, glycine, and glutamine

A

Aspartate, glycine, and glutamine

83
Q
  1. A patient has been recently diagnosed with colorectal cancer. The physician treats the patient with a combination of chemotherapeutic drugs, one of which is 5-fluorouracil (5-FU). 5-FU is effective as an anticancer drug because it inhibits which one of the following enzymes?

A. Dihydrofolate reductase
B. Thymidylate synthase
C. Amidophosphoribosyl transferase

D. 5’-phosphoribosyl-1’-pyrophosphate (PRPP) synthetase

A

Thymidylate synthase

84
Q
  1. A patient exhibits fasting hypoglycaemia and lactic acidosis under fasting conditions. Hepatomegaly is also evident. A glucagon challenge only releases about 10% of the expected level of glucose from the liver. The patient has also developed gout due to an increase in the levels of which of the following metabolites?
    A. PRPP
    B. Glutamine
    C. ATP
    D. NADH
85
Q
  1. Individuals with gout are given febuxostat for long-term management of the disease. In such individuals, which of the following bases would accumulate in the urine?

A. Urate and xanthine
B. Guanine and adenine
C. Xanthine and guanine
D. Hypoxanthine and xanthine

A

Hypoxanthine and xanthine

86
Q
  1. A penicillin-allergic child was given a sulfonamide for otitis media. Human cells are resistant to sulfonamides due to which of the following?

A. Sulfonamides are specific for prokaryotic DNA polymerases
B. Sulfonamides are specific for prokaryotic RNA polymerases

C. Sulfonamides inhibit a metabolic pathway not present in eukaryotic cells

D. Sulfonamides inhibit bacterial ribonucleotide reductase, but not eukaryotic ribonucleotide reductase

A

C. Sulfonamides inhibit a metabolic pathway not present in eukaryotic cells

87
Q
  1. Many anticancer drugs re given to patients in their nucleoside form, rather than the nucleotide form. Which enzyme below will be required in the conversion of deoxyguanosine to dGTP?
    A. Pyrimidine nucleoside phosphorylase
    B. Deoxyguanosine kinase
    C. Ribonucleotide reductase
    D. Adenine phosphoribosyltransferase
A

Ribonucleotide reductase

88
Q
  1. Pyrimidines differ from purines in both structure and metabolite solubility. Which of the following is a pyrimidine base?

A. Uracil
B. Guanine
C. Inosine
D. Adenine

89
Q
  1. Phosphates attached to nucelotides provide energy for chemical reactions. The phsphates in GTP are attached to what entity of the nucleotide?
    A. Ribose sugar
    B. Guanine base
    C. Deoxyribose sugar
    D. The ether oxygen of the glycosidic bond
A

Ribose sugar

90
Q
  1. In biochemistry, it is important to identify the charge of molecules to determine their chemical behaviour when present in solution. Which of the following is negatively charged at physiologic pH?

A. Nucleotide
B. Nucleoside
C. Purine base

D. Pyrimidine base

A

Nucleotide

91
Q
  1. Watson and Crick, in their ground-breaking paper, found that the nucleotides in RNA and DNA are linked together by:

A. N-glycosidic bonds
B. Phosphodiester bonds
C. Acid anhydride bonds
D. Hydrogen bonds

A

Phosphodiester bonds

92
Q
  1. This amino acid precursor contributes 2 carbon atoms and 1 nitrogen atom to the purine ring structure:

A. Aspartate
B. Glutamine
C. Glycine
D. Alanine

93
Q
  1. Carbamoyl phosphate, a substrate in pyrimidine nucleotide synthesis, is also an intermediate of this pathway:

A. Pentose phosphate pathway
B. Urea cycle
C. Polyol cyle
D. β-oxidation

A

Urea cycle

94
Q
  1. The rate-limiting enzyme of purine nucleotide synthesis immediately forms this product:
    A. Phosphoribosyl pyrophosphate
    B. Ribose-5-phosphate

C. Insoine monophosphate
D. Carbamoyl phosphate

A

Phosphoribosyl pyrophosphate

95
Q
  1. Which of the following statements is true of the regulation of purine nucleotide synthesis?

A. The presence of both AMP and GMP activates glutamyl amidotransferase

B. An increase in the concentration of PRPP decreases purine nucleotide sequences

C. The synthesis of AMP increases when the concentration of GMP increases

D. The rate of purine biosynthesis decreases when glucose-6-phosphatase activity increases

A

The synthesis of AMP increases when the concentration of GMP increases

96
Q
  1. The C2 of the pyrimidine ring is derived from:
    A. Carbamoyl phosphate
    B. Glycine
    C. Tetrahydrofolate
    D. Aspartate
A

Carbamoyl phosphate

97
Q
  1. Which of the following is synthesized by completing the base component first, then adding the sugar entity afterwards?

A. Cytosine
B. Guanine
C. Inosine
D. Adenine

98
Q
  1. The phosphate component in pyrimidine nucleotides is attached to the:
    A. Ribose sugar
    B. Guanine base
    C. Deoxyribose sugar

D. Ether oxygen of the glycosidic bond

A

Ribose sugar

99
Q
  1. Which of the following is negatively charged at physiologic pH?
    A. Nucleotide
    B. Nucleoside
    C. Purine base
    D. Pyrimidine base
A

Nucleotide

100
Q
  1. Which of the following has an adenine-containing nucleotide in its structure?
    A. PRPP
    B. Coenzyme A
    C. Carbamoyl phosphate
    D. SAM
A

Coenzyme A

Biochemisty Main (29 decks)

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