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BIOCHEMISTRY > 2ND BIMONTHLY QUIZZES > Flashcards

2ND BIMONTHLY QUIZZES Flashcards

1
Q

disease in which it has death from heart failure by age 2 but with adult onset variant

A

Pompe disease

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2
Q

Which of the following statements about gluconeogenesis is correct?

A. Glucose 6-phosphatase hydrolyzes glucose 6-phosphate and is found in liver and muscle

B. Fructose 1, 6-biphosphatase converts fructose 1, 6-bisphosphate into fructose 1-phosphate

C. Pyruvate is first converted to phosphoenolpyruvate by phosphoenolpyruvate carboxykinase

D. Glucose 6-phosphatase hydrolyzes glucose 6-phosphate to release glucose into the blood

A

Glucose 6-phosphatase hydrolyzes glucose 6-phosphate to release glucose into the blood

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3
Q

The main source of glucose carbons for gluconeogenesis

A

Alanine

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4
Q

Which of the following intermediates can glucose be converted to glycerol-3-phosphate

A

dihydroxy acetone phosphate

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5
Q

In an individual at rest, who has fasted for 12 hours, which of the following occurs? *

A

phosphorylase, pyruvate kinase and glycogen synthase are phosphorylated in liver

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6
Q

Which one of the following statements is INCORRECT

A. Insulin suppresses the effect of cAMP by inhibiting the activation of phosphorylase b

B. Phosphorylase a and phosphorylase kinase a are dephosphorylated and inactivated by protein phosphatase I

C. None of the statements is incorrect.

D. cAMP controls both the activation and inactivation of phosphorylase

A

A. Insulin suppresses the effect of cAMP by inhibiting the activation of phosphorylase b

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7
Q

Which enzyme does 3- Phosphoglycerate is isomerized to 2- Phosphoglycerate?

A

Phosphoglycerate mutase

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8
Q

What is the main function of the pentose phosphate pathway?

A

supply pentoses and NADPH

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9
Q

Which one of the following diseases has hepatomegaly, mild hypoglycemia but has generally good prognosis? *

A

Hers disease

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10
Q

In the pentose phosphate pathway, which of the following are the major products? *

A

ribose and NADPH

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11
Q

Which of the following enzyme is NAD dependent catalyzing this oxidation

A

Glyceraldehyde 3-phosphate dehydrogenase

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12
Q

which one of the following is TRUE about glycogen?

A.Three quarters of total body glycogen is in muscle.

B. It occurs in liver and in muscle.

C. A branch polymer of alpha D glucose

D. All of the statement is true.

A

D. All of the statement is true.

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13
Q

What is the key regulatory enzyme of Hexose Monophosphate Pathway?

A

glucose-6-P dehydrogenase

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14
Q

What enzyme is catalyzing glucose 6- phosphate to fructose-6- phosphate? *

A

Phosphohexose isomerase

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15
Q

Which of the following statements about the nonoxidative section of the pentose phosphate pathway(PPP) is correct? *

A. transketolase is an enzyme that transfers 3 carbon units in the PPP

B. transaldolase is an enzyme that transfers 2 carbon units in the PPP

C. pentoses can provide glycolytic intermediates in this phase of PPP

D. the non-oxidative reactions of the PPP are not reversible.

A

C. pentoses can provide glycolytic intermediates in this phase of PPP

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16
Q

Which one of the following statements is INCORRECT?

A. There are different isoenzymes of glycogen phosphorylase in liver, muscle and brain, encoded by different genes.

B. None of the statements is incorrect.

C. When a growing chain is at least 11 glucose residues long, branching enzyme transfers a part of the 1-4 chain to a neighboring chain to form a 1-6 linkage.

D. The terminal glucosyl residues from the outermost chains of the glycogen molecule are removed sequentially until approximately 6 glucose residues remain on either side of a 1-4 branch.

A

D. The terminal glucosyl residues from the outermost chains of the glycogen molecule are removed sequentially until approximately 6 glucose residues remain on either side of a 1-4 branch.

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17
Q

Which of the following enzymes acts in the pentose phosphate pathway? *

A

6 phosphogluconate dehydrogenase

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18
Q

Which of the following are considered as the major sites of regulation of glycolysis? *

A

Hexokinase, phophofructokinase, pyruvate kinase

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19
Q

Which one of the following enzymes causes accumulation of polysaccharide with few branch points?

A

Branching enzyme

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20
Q

Which of the following statements is INCORRECT?

A. The highly branched structure of glycogen provides a large number of sites for glycogenesis, permitting rapid release of glucose 1 phosphate.

B. None of the statements is incorrect.

C. The liver concentration of glycogen is about 450mmol/L after a meal falling to about 200mmol/L after an overnight fast.

D. Glycogen storage diseases are a group of inherited disorders characterized by deficient mobilization of glycogen or abnormal forms of glycogen

A

B. None of the statements is incorrect.

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21
Q

Which of the following enzymes catalyzes the conversion of pyruvate to oxaloacetate?

A

Pyruvate carboxylase

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22
Q

Which one of the following causes death from heart or liver failure before age 5?

A

Branching enzyme

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23
Q

Which of the following enzymes synthesized NADPH?

A

glucose 6 phosphate dehydrogenase

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24
Q

Which of the following is not an important precursor of glucose in animals? *

A

Glucose 6-phosphate

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25
Q

Which one of the following enzymes is deficient causing neutropenia?

A

Endoplasmic reticulum glucose 6 phosphate transporter

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26
Q

What enzyme in the muscle does glucose phosphorylated to glucose-6-phosphate?

A

Hexokinase

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27
Q

Glutamate is metabolically converted to α-ketoglutarate and NH4+ by a process

A

Deamination

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28
Q

What enzyme is involved in converting from Ribulose 5-phosphate to Xylulose 5-phosphate ?

A

phosphopentose epimerase

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29
Q

In erythrocytes, Which of the following enzyme bypassed phosphoglycerate kinase?

A

Bisphoglycerate mutase

30
Q

Which one of the following statements is INCORRECT?

A. None of the statements is incorrect.

B. Glycogen synthase catalyzes the formation of a glycoside bond between C-1 of a terminal glucose residue of glycogen and C-4 of the glucose of UDPGlc.

C. The addition of a glucose residue to a preexisting glycogen chain or primer occurs at the non reducing outer end of a molecule.

D. The initial steps in glycogen synthesis involves glycogenin.

A

B. Glycogen synthase catalyzes the formation of a glycoside bond between C-1 of a terminal glucose residue of glycogen and C-4 of the glucose of UDPGlc.

31
Q

An enzyme used in both glycolysis and gluconeogenesis is:

A

3-phosphoglycerate kinase

32
Q

What is the total per mol of glucose under anaerobic conditions?

A

2

33
Q

In oxidation of pyruvate to acetyl-CoA, the reaction is said to be complete when

A

Reduced lipoamide is reoxidized by dihydrolipoyl dehydrogenase

34
Q

During the carbohydrate feeding, there is a decrease action of pyruvate carboxylase, which of the following can inhibit this action?

A

ADP

35
Q

What would C-1 of glucose be expected to end up principally in a tissue that metabolizes glucose via the pentose phosphate pathway?

A

carbon dioxide

36
Q

Which of the following enzymes prevent simple reversal of glycolysis for gluconeogenesis?

A

hexokinase, phosphofructokinase, pyruvate kinase

37
Q

Which of the following statements about the oxidative section of the pentose phosphate pathway is correct?

A. the pentose phosphate pathway oxidizes NADPH to NADP+

B. the pentose phosphate pathway generates NADH.

C. the pathway supplies ribose-5-phosphate and NADPH in quantities the cells require.

D. the pathway is highly active in the fasting state

A

C. the pathway supplies ribose-5-phosphate and NADPH in quantities the cells require.

38
Q

Which of the following statement is correct?

A. As more glucose is phophorylated by glucokinase, there is increased glycolysis leading to increased formation of ADP

B. The resultant outflux of calcium ions leads to fusion of the insulin secretory granules with the cell membrane and the release of insulin

C. Hexokinase detects high concentrations of glucose

D. Closure of ATP potassium channel and opening voltage-gated calcium channel results from increased formation of ATP

A

D. Closure of ATP potassium channel and opening voltage-gated calcium channel results from increased formation of ATP

39
Q

Which one of the following statements is INCORRECT

A. Active phosphorylase a in both tissues is allosterically inhibited by ATP and glucose 6 phosphate; in liver, but not muscle, free glucose is also an inhibitor.

B. Phosphorylation of glycogen synthase increases its activity, phosphorylation of glycogen phosphorylase reduces its activity.

C. Glycogen synthase and glycogen phosphorylase are regulated in opposite directions by allosteric mechanisms and covalent modifications.

D. cAMP formed from ATP by adenylyl cyclase at the inner surface of cell membranes in response to epinephrine, norepinephrine and glucagon.

A

B. Phosphorylation of glycogen synthase increases its activity, phosphorylation of glycogen phosphorylase reduces its activity.

40
Q

Gluconeogenesis responds to which of the following? *

A. blood control

B. pH control

C. hormonal control

D. temperature control

A

C. hormonal control

41
Q

Which one of the following statements is INCORRECT?

A. None of the statements is incorrect.

B. The debranching enzyme has two catalytic sites in a single polypeptide chain.

C. The 1,6 glycosidase catalyzes the hydrolysis of the 1-6 glycoside bond that transfers a trisaccharide unit from 1 branch to the other.

D. The reaction catalyzed by phosphoglucomutase is reversible, so that glucose 6 phosphate can be formed from glucose 1 phosphate.

A

C. The 1,6 glycosidase catalyzes the hydrolysis of the 1-6 glycoside bond that transfers a trisaccharide unit from 1 branch to the other.

42
Q

In gluconeogenesis, what coenzyme is required by pyruvate carboxylase to convert pyruvate to oxaloacetate?

A

biotin

43
Q

Which enzyme is not present in muscle?

A

Glucose-6-phosphatase

44
Q

Which of the following substrates CANNOT contribute to net gluconeogenesis in mammalian liver?

A

Palmitate

45
Q

Which of the following statement is true on pyruvate dehydrogenase?

A. Regulated when there is adequate ATP oxidized fatty acids

B. Regulated by acetyl-CoA and NADH

C. Inhibited when there is adequate ATP oxidized fatty acids

D. Inhibited by phosphorylation of three serine residues

A

C. Inhibited when there is adequate ATP oxidized fatty acids

46
Q

Enzyme responsible for removing glucose from hepatic portal blood following a meal regulating the concentration of glucose available to peripheral tissue.

A

Glucokinase

47
Q

What molecule inhibits enzyme Enolase

A

Fluoride

48
Q

Which one of the following statements is INCORRECT?

A. Ca synchronizes the activation of glycogen phosphorylase with muscle contraction.

B. Muscle is insensitive to glucagon.

C. cAMP activates cAMP dependent protein kinase, which catalyzes the phosphorylation by ATP of inactive phosphorylase kinase b to active phosphorylase kinase a.

D. cAMP is formed in response to glucagon, which is secreted in response to rising blood glucose.

A

D. cAMP is formed in response to glucagon, which is secreted in response to rising blood glucose.

49
Q

Which of the following statement is not correct? *

A. Pyruvate is reduced to lactate catalyzed by lactate dehydrogenase in anaerobic conditions.

B. The NADH cannot be reoxidized through the respiratory chain in anaerobic conditions.

C. The reducing equivalents from the NADH formed in glycolysis are taken up into the cytosol for oxidation via either the malate-aspartate shuttle or the glycerophosphate shuttle.

D. Pyruvate is transported into mitochondria and undergoes oxidative decarboxylation to acetyl-Coa in the aerobic conditions.

A

C. The reducing equivalents from the NADH formed in glycolysis are taken up into the cytosol for oxidation via either the malate-aspartate shuttle or the glycerophosphate shuttle.

50
Q

The enzyme itself is phosphorylated and the phosphate group takes part in a reversible reaction

A

Phosphoglucomutase

51
Q

Which of the following molecule is not considered as long chain fatty acids?

A. docosahexaenoic
B. a-linoleic
C. EPA
D. a-linolenic

A

B. a-linoleic

52
Q

Which one of the following statements is CORRECT? *

A. Simple lipids are esters of fatty acids containing groups in addition to an alcohol and one or more fatty acids.

B. Glycolipids are complex lipids which contains fatty acid, sphingosine and carbohydrate.

C. Phospholipids are complex lipids which contains fatty acids, sphingosine and carbohydrate.

D. Lipids may be classified as precursor and derived lipids which includes lipid-soluble vitamins, proteins, ketone bodies.

A

B. Glycolipids are complex lipids which contains fatty acid, sphingosine and carbohydrate.

53
Q

This is found in certain fats in small amounts (especially butter) , an end product of carbohydrate fermentation by rumen organisms.

A

Butyric

54
Q

Which one of the following statements is INCORRECT?

A. Simple lipids include fats and waxes which are esters of fatty acids with various alcohols.

B. Fatty acids that occur in natural fats usually contain an even number of carbon atoms.

C. Complex lipids are esters of fatty acids containing groups in addition to an alcohol and one or more fatty acids.

D. Fatty acids occur in the body mainly as esters in natural fats and oils, and are also found in the esterified form as free fatty acids, a transport form in the plasma.

A

D. Fatty acids occur in the body mainly as esters in natural fats and oils, and are also found in the esterified form as free fatty acids, a transport form in the plasma.

55
Q

Which of the following fatty acid has 16 carbon atoms? *

A

Palmitic acid

56
Q

What is the important component of fish oils( eg, cod liver, mackerel, menhaden, salmon oils)? *

A. all-cis-5,8,11,14- Eicosatetraenoic
B. all-cis-9,12,15- Octadecatrienoic
C. all-cis-4,7,10,13,16,19- Docosahexaenoic
D. all-cis-5,8,11,14,17- Eicosapentaenoic

A

D. all-cis-5,8,11,14,17- Eicosapentaenoic

57
Q

Which of the following fatty acids is a precursor of prostaglandins?

arachidonic acid
linolenic acid
linoleic acid
oleic acid

A

arachidonic acid

58
Q

Which one of the following statements is CORRECT?

A. Leukotrienes synthesized in vivo by cyclization of the center of eicosanoic polyunsaturated fatty acids

B. Leukotrienes and lipoxins are characterized by the presence by the presence of three or four conjugated double bonds.

C. Thromboxanes are derivatives formed via lipoxygenase pathway.

D. Prostacyclins have cyclopentane ring with interrupted oxygen atom.

A

B. Leukotrienes and lipoxins are characterized by the presence by the presence of three or four conjugated double bonds.

59
Q

A 3 years old, female, came in due to dyspnea. Upon physical examination the patient had tachypnea, nasal flaring, and wheezing upon auscultation. What is the mechanism?

A. The child is deficient with dipalmitoyl lecithin which causes respiratory distress syndrome.

B. None of the statements.

C. Leukotrienes causes bronchoconstriction.

D. Dipalmitoyl lecithin is very effective surface-active agent which prevents adherence and lung collapse

A

C. Leukotrienes causes bronchoconstriction.

60
Q

Which one of the following statements is INCORRECT?

A. Geometric isomerism occurs in unsaturated fatty acids.

B. Double bonds in naturally occurring unsaturated long chain fatty acids are nearly all in the cis configuration, the molecules being “bent” 120 degrees at the double bond.

C. The carbon chains of saturated fatty acids form a zigzag pattern when extended low temperatures.

D. Biomembranes become thicker with increases in temperature.

A

D. Biomembranes become thicker with increases in temperature.

61
Q

Which of the following is a storage form of lipid?

Phospholipid
Glycolipid
Sufolipid
Triacylglycerol

A

Triacylglycerol

62
Q

Which one of the following forms the lipid bilayer of the cell membranes?

Phosphatidylinositol
Phosphatidylethanolamine
Phophatidylserine
Glycerophospholipids

A

Glycerophospholipids

63
Q

This is a very effective surface-active agent and a major constituent of the surfactant preventing adherence, due to surface tension, of the inner surfaces of the lungs.

Cephalin
Dipalmitoyl lecithin
Ceramide
Sphingosine

A

Dipalmitoyl lecithin

64
Q

Which one of the following statements is CORRECT? *

A. The combination of sphingosine plus protein is known as ceramide.

B. Phosphatidylenolamine plays a role in apoptosis.

C. Spingomyelins contain no glycerol and yields a fatty acid, phosphoric acid, choline and sphingosine on hydrolysis.

D. Phosphatidylserine are believed to play a role in cell signaling and in apoptosis.

A

C. Spingomyelins contain no glycerol and yields a fatty acid, phosphoric acid, choline and sphingosine on hydrolysis.

65
Q

These are found in large quantities in the myelin sheath that surrounds nerve fibers. *

Phospholipids
Sphingomyelins
Phosphatidylethanolamine
Phosphatidylserine

A

Sphingomyelins

66
Q

Which one of the following statements is INCORRECT of Cholesterol? *

A. Widely distributed in all cells of the body but particularly in nervous tissue

B. None of the statements is incorrect.

C. Simple hexagonal ring denotes a completely saturated 6 carbon ring with all valences satisfied by hydrogen bonds

A

D. Methyl side chains are shown as double bonds attached at the farther (methyl) end.

SHOULD BE Methyl side
chains are shown as single bonds unattached at the farther (methyl) END

67
Q

A common name in unsaturated fatty acids which occurs frequently seen in animal fats, and is important component of phospholipids in animals.

A

Arachidonic

68
Q

What is the precursor of Vitamin D? *

A

Ergosterol

69
Q

Which one of the following statements is INCORRECT?

A. Peroxidation of lipids exposed to oxygen is responsible not only for deterioration of foods but also for damage to tissued in vivo.

B. Lipid peroxidation is a source of free radical.

C. The deleterious effects are considered to be caused by free radicals, molecules that have paired valence electrons , making them unreactive.

D. None of the statements is incorrect.

A

C. The deleterious effects are considered to be caused by free radicals, molecules that have paired valence electrons , making them unreactive.

SHOULD BE

The deleterious effects are considered to be
caused by free radicals, molecules that have unpaired valence electrons,
making them highly reactive.

70
Q

Which of the following statements is free fatty acids carried by in the bloodstream? *

bound to hemoglobin
carried by albumin
freely soluble in the aqueous phase of the blood
present at levels that are independent of epinephrine

A

carried by albumin

71
Q

Which one of the following is frequently found with linoleic acid but particularly in linseed oil? *

Alpha Linolenic
Linoleic
Arachidonic
Oleic

A

Alpha Linolenic

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