Exam 3 - True/False Questions

Question 1

Consider the overview of the acylglycerol biosynthesis. Which of the followings statements is incorrect (or False)?
Select one:
a. Phosphatidate is used to make Cardiolipin and Phosphatidylinositol
b. Diacylglycerol is used to make Lecithin, Cephalin and Triglycerides.
c. Dihydroxyacetone phosphate is used to make Plasmalogens and PAFs.
d. Phosphatidate can be converted to diacylglycerol by phosphorylation.

Answer 1

d. Phosphatidate can be converted to diacylglycerol by phosphorylation.

ACYLTRANSFERASE can be converted to diacylglycerol by phosphorylation.

Question 2

Which of the following statements about Group I and Group II hormones are incorrect (False)? (more than one answer). Please be careful - there is a penalty for each incorrect answer.

Select one or more:

a. Calcitriol are classified as Group II hormones and are Lipophilic in nature.
b. The half life of Group I hormones are very short (minutes)
c. Catecholamines are classified as hormones that interact via (or with) intracellular receptors.
d. Group II hormones use secondary messengers like Ca+2, cAMP, cGMP

Answer 2

a. Calcitriol are classified as Group II hormones and are Lipophilic in nature.
b. The half life of Group I hormones are very short (minutes)
c. Catecholamines are classified as hormones that interact via (or with) intracellular receptors.

Calcitriol is GROUP I and lipophilic

The half-life of Group I hormones is VERY LONG

Catecholamines bind to CELL SURFACE RECEPTORS

Question 3

Which of the following statements about biosynthesis of prohormones are correct (True) (more than one answer). Please be careful - incorrect answers will attract a penalty.

Select one or more:

a. Insulin is synthesized as a preprohormone and modified to form the two chains of 21 and 30 amino acids each.
b. Angiotensin II is an octapeptide from Angiotensinogen (about 400 amino acids).
c. PTH is an 84 amino acid peptide
d. Angiotensin Converting Enzyme (ACE), a glycoprotein found in the lungs, endothelial cells and plasma removes 2 amino acids from the decapeptide, Angiotensin I to form Angiotensin II

Answer 3

a. Insulin is synthesized as a preprohormone and modified to form the two chains of 21 and 30 amino acids each.
b. Angiotensin II is an octapeptide from Angiotensinogen (about 400 amino acids).
c. PTH is an 84 amino acid peptide
d. Angiotensin Converting Enzyme (ACE), a glycoprotein found in the lungs, endothelial cells and plasma removes 2 amino acids from the decapeptide, Angiotensin I to form Angiotensin II

Question 4

Which of the following statements about the classification of hormones are correct (or True). (More than one answer). Be careful, each incorrect answer will draw a penalty

Select one or more:

a. Glucagon uses cGMP as secondary messenger
b. Atrial Natriuretic factor uses cAMP as secondary messenger
c. Glucocorticoid is an example of a hormone that binds to intracellular receptors.
d. Vasopressin (Antidiuretic hormone) uses Ca+2 as a secondary messenger

Answer 4

c. Glucocorticoid is an example of a hormone that binds to intracellular receptors.
d. Vasopressin (Antidiuretic hormone) uses Ca+2 as a secondary messenger

Glucagon USES CELL SURFACE RECEPTORS

Atrial Natriuretic Factor uses cGMP as secondary messenger

Question 5

Which of the following statements about Biosynthesis of various hormones are correct (True)? (more than one answer). Please be careful - a wrong answer will attract a penalty.

Select one or more:

a. Pregnenolone is synthesized from Cholesterol using P450scc
b. The most significant metabolic product of testosterone is DHT (Dihydrotesterone) which is obtained from Testosterone using 5 alpha reductase
c. Cortisol synthesis requires 3 hydroxylases at C11, C17 and C21
d. The major androgen precursor produced by the adrenal cortex is dehydroepiandosterone (DHEA)

Answer 5

a. Pregnenolone is synthesized from Cholesterol using P450scc
b. The most significant metabolic product of testosterone is DHT (Dihydrotesterone) which is obtained from Testosterone using 5 alpha reductase
c. Cortisol synthesis requires 3 hydroxylases at C11, C17 and C21
d. The major androgen precursor produced by the adrenal cortex is dehydroepiandosterone (DHEA)

Question 6

Which of these statements about ALA synthase is incorrect (or False)?
Select one:
a. ALA synthase is the key regulatory enzyme in hepatic biosynthesis of heme.
b. Many drugs increase cytochrome P450 biosynthesis.
c. Many drugs induce ALAS1 biosynthesis and this increases heme production.
d. ALAS2 is also regulated by heme and also induced by drugs.

Answer 6

d. ALAS2 is also regulated by heme and also induced by drugs.

ALAS2 in NOT regulated by heme and is NOT induced by drugs

Question 7

Which of the following statements is incorrect (or False)?
Select one:
a. Phospholipases allow degradation and remodeling of phosphoglycerols.
b. Lysolecithin can be formed by using Phospholipase A2 on phosphatidylcholine.
c. Plasmalogen contains a saturated ether, an acyl group and an phosphoethanolamine on a glycerol molecule.
d. PAF contains a saturated ether, an acyl group and a phosphocholine on a glycerol molecule.

Answer 7

c. Plasmalogen contains a saturated ether, an acyl group and an phosphoethanolamine on a glycerol molecule.

Plasmalogen contains an ETHER LINKAGE, an acyl group and an phosphoethanolamine on a glycerol molecule.

Question 8

Consider the various examples of Sphingolipidoses. Which of the following statements is incorrect (or False)?
Select one:
a. Tay-Sachs disease is due to the deficiency in hexosamindase A
b. Fabry’s disease is due to the deficiency in alpha Galactosidase.
c. Gaucher’s disease is due to the deficiency in beta Glucosidase.
d. Niemann-Pick disease is due to the deficiency in Ceramidase

Answer 8

d. Niemann-Pick disease is due to the deficiency in Ceramidase

Niemann-Pick disease is due to the deficiency of SPINGOMYELINASE

Question 9

Which of the following statements in the metabolism of acylglycerols and sphingolipids is incorrect (or False)?
Select one:
a. Hydrolysis initiates catabolism of triacylglycerols.
b. Diacylglycerol is the common precursor in the biosynthesis of many phosphoglycerols and cardiolipin.
c. Triacylglycerols and phosphoglycerols are formed by acylation of triose phosphates.
d. Deficiency of lung surfactant causes respiratory distress syndrome.

Answer 9

b. Diacylglycerol is the common precursor in the biosynthesis of many phosphoglycerols and cardiolipin.

Diacylglycerol is the common precursor in the biosynthesis of
PHOSPHATIDYLCHOLINE, Phosphatidylethanolamine, and TRIANCYLGLYCEROL

Question 10

Which of the following statements is correct? (Multiple correct answers)

Select one:

a. Triacylglycerols are the major energy storing lipids.
b. Glycosphingolipids, sphingomyelins have structural functions in cell membranes.
c. Phospholipids and sphingolipids are involved in several disease processes including infant respiratory distress syndrome, multiple sclerosis and sphingolipidosis.
d. GlcCer (glucosylceramide) is the major glycosphingolipid of extraneural tissues, whereas GalCer (Galactosylceramide) is the major lipid of myelin.

Answer 10

a. Triacylglycerols are the major energy storing lipids.
b. Glycosphingolipids, sphingomyelins have structural functions in cell membranes.
c. Phospholipids and sphingolipids are involved in several disease processes including infant respiratory distress syndrome, multiple sclerosis and sphingolipidosis.
d. GlcCer (glucosylceramide) is the major glycosphingolipid of extraneural tissues, whereas GalCer (Galactosylceramide) is the major lipid of myelin.

Question 11

Consider the biosynthesis of ceramide. Which of the following statements is incorrect (or False)?
Select one:
a. Ceramide is made by condensing StearoylCoA and Serine.
b. In the biosynthesis process, an intermediate: 3-ketosphinganine is oxidized to dihydrosphingosine
c. In the final step, dihydroceramide desaturate oxidizes dihydroceramide to ceramide.
d. Dihydrosphingosine is a reduced product of 3-ketosphinganine.

Answer 11

a. Ceramide is made by condensing StearoylCoA and Serine.

Ceramide is made by condensing PALMITOYL-COA and Serine.

Question 12

Which of the following statements about classification of porphyrias is correct (or True)?
Select one:
a. Porphyrias may be termed as erythropoietic or hepatic based on the organ most affected.
b. Barbiturates induce production of cytochrome P450
c. Individuals with low ALAS2 develop anemia, not porphyria
d. There is no known defect of ALAS1

Answer 12

a. Porphyrias may be termed as erythropoietic or hepatic based on the organ most affected.
b. Barbiturates induce production of cytochrome P450
c. Individuals with low ALAS2 develop anemia, not porphyria
d. There is no known defect of ALAS1

Question 13

Which of the following statements about Heme biosynthesis and metabolism is incorrect (or False)?
Select one:
a. There are 4 methyls, 2 propionate and 2 vinyl group groups present in the four pyrrole rings of heme.
b. Biosynthesis of heme involves 6 enzyme catalyzed reactions.
c. Synthesis of heme commences with the condensation of succinylCoA and Glycine.
d. Genetic abnormalities of seven of the eight enzymes of heme biosynthesis result in inherited porphyrias.

Answer 13

a. There are 4 methyls, 2 propionate and 2 vinyl group groups present in the four pyrrole rings of heme.
b. Biosynthesis of heme involves 6 enzyme catalyzed reactions.

There are 8 methyls, 8 propionate and 8 vinyl group groups present in the four pyrrole rings of heme.

Biosynthesis of heme involves 8 enzyme catalyzed reactions.

Question 14

Which of the following statements about disorders of bilirubin metabolism is incorrect (or False)?
Select one:
a. Neonatal physiologic jaundice, also called as the Dubin Johnson syndrome, results from decrease in the hemolysis of bilirubin because of the immature hepatic system for uptake, and conjugation of bilirubin.
b. Hyperbilirubinemia causes jaundice.
c. If 30% of the bilirubin UDP-glucouronosyl transferase activity is retained, Gilbert syndrome is harmless.
d. Obstruction in the biliary tree is the most common cause of conjugated hyperbilirubinemia.

Answer 14

a. Neonatal physiologic jaundice, also called as the Dubin Johnson syndrome, results from decrease in the hemolysis of bilirubin because of the immature hepatic system for uptake, and conjugation of bilirubin.

Dupin-Johnson Syndrome is due to CONJUGATED HYPERBILIRUBINEMIA in childhood or during adult life and is caused by mutations in the gene encoding the protein involved in the secretion of conjugated bilirubin into bile.

Question 15

Which of the following statements about Heme biosynthesis and metabolism is incorrect (or False)?
Select one:
a. Catabolism of the heme ring by the mitochondrial enzyme heme oxygenase, produces biliverdin.
b. Oxidation of biliverdin produces bilirubin which is transported to the liver bound to serum albumin.
c. Most of the bilirubin excreted in bile of mammals is bilirubin diglucouronide.
d. Intestinal bacteria reduce conjugated bilirubin to urobilinogen.

Answer 15

b. Oxidation of biliverdin produces bilirubin which is transported to the liver bound to serum albumin.

REDUCTION of biliverdin produces bilirubin which is transported to the liver bound to serum albumin.

Question 16

Which of the following statements about the protoporhyrin ring is correct (or True)?

Select one:

a. In the metabolism of heme, bilirubin is the oxidized form of biliverdin.
b. It contains a tetrapyrrolidine ring in its structure
c. The acetate group in uroporphyrin III is reduced to methyl groups in Coporphyrinogen
d. In the metabolism of the heme, biliverdin is a linear chain containing three lactam (2-oxopyrrole) rings.

Answer 16

b. It contains a tetrapyrrolidine ring in its structure
c. The acetate group in uroporphyrin III is reduced to methyl groups in Coporphyrinogen

In the metabolism of the heme, biliverdin is a linear chain containing FOUR? lactam (2-oxopyrrole) rings.

In the metabolism of heme, bilirubin is the REDUCED form of biliverdin.

Question 17

Which of the following statements about hemoproteins is not correct (or False)?
Select one:
a. Cytochrome c is hemoprotein involved in the electron transport chain.
b. Cytochrome P450 is also a hemoprotein involved in hydroxylation of xenobiotics.
c. Catalase is a hemoprotein involved in the degradation of hydrogen peroxide.
d. ALA synthase is a hemoprotein involved in the synthesis of delta aminolevulinate.

Answer 17

d. ALA synthase is a hemoprotein involved in the synthesis of delta aminolevulinate.

ALA synthase is an ENZYME involved in the synthesis of delta aminolevulinate.

Question 18

Which of the following statements about biosynthesis of heme is incorrect (or False)?
Select one:
a. Synthesis on of heme takes place in the cytosol
b. Ferrochelatase enzyme acts on protoporphyrin III in the mitochondria.
c. Oxidation of Coporphyrinogen III takes place twice in the mitochondria to form protoporphyrin III.
d. Synthesis of coproporphyrinogen III takes place in the cytosol.

Answer 18

a. Synthesis on of heme takes place in the cytosol

Synthesis of heme takes place in the MITOCHONDRIA AND CYTOSOL

Question 19

Which of the following statements about ALA synthase is incorrect (or False)?
Select one:
a. There are two isoenzymes of ALA synthase.
b. Heme acts as a positive regulator of the synthesis of ALAS1
c. ALAS2 is expressed in erythrocytes.
d. ALAS1 is expressed throughout the body.

Answer 19

b. Heme acts as a positive regulator of the synthesis of ALAS1

Heme acts as a NEGATIVE REGULATOR of the synthesis of ALAS1

Question 20

Which of the following statements is False?
Select one:
a. Nucleoside triphosphates have a low group transfer potential.
b. The Nucleoside triphosphates participate in covalent bond synthesis.
c. cAMP and cGMP function as intracellular second messengers.
d. All phosphodiester bonds are 3 prime to 5 prime.

Answer 20

a. Nucleoside triphosphates have a low group transfer potential.

Nucleoside triphosphates have a HIGH group transfer potential.

Question 21

Which of the following statements is False?
Select one:
a. Carbon 2 on Cytosine contains the oxo group.
b. Thymine and Uracil have Oxo groups on 2 and 4.
c. Guanine has a 1o amine on carbon 4.
d. Cytidine and Uridine have glycosidic bond at carbon number 1

Answer 21

c. Guanine has a 1o amine on carbon 4.

Guanine has a 1o amine on CARBON 2.

Question 22

Which of the following statements is False?
Select one:
a. The ribose or deoxy ribose is linked to N-1 of a pyrimidine and N-9 of a purine.
b. The bond formed between the N-1 and N-9 with the purine and pyrimidine is a B-glycosidic bond.
c. The Beta-glycosidic bond’s syn conformers predominate.
d. A prime number indicates the amine to which the phosphoryl group of the sugars mononucleotides is attached.

Answer 22

d. A prime number indicates the amine to which the phosphoryl group of the sugars mononucleotides is attached.

A prime number indicates the HYDROXYL to which the phosphoryl group of the sugars mononucleotides is attached.

Question 23

Which of the following statements about the genetic code is not true?
Select one:
a. The code is ambiguous 
b. The code is non overlapping
c. The code has not punctuation
d. The code is universal

Answer 23

a. The code is ambiguous

The code is NOT ambiguous

Question 24

Which of the following statements about the formation of the peptidyl bond in protein formation is True (or Correct)?
Select one:
a. The alpha amino group of the incoming amino acid at the “A” site carries out a nucleophilic attack on the amide group of the peptidy-tRNA at the “P” site.
b. The alpha amino group of the incoming amino acid at the “A” site carries out a nucleophilic attack on the ester group of the peptidy-tRNA at the “P” site.
c. The alpha carboxyl group of the incoming amino acid at the “A” site carries out a nucleophilic attack on the amide group of the peptidy-tRNA at the “P” site.
d. The alpha carboxyl group of the incoming amino acid at the “A” site carries out a nucleophilic attack on the ester group of the peptidy-tRNA at the “P” site

Answer 24

b. The alpha amino group of the incoming amino acid at the “A” site carries out a nucleophilic attack on the ester group of the peptidy-tRNA at the “P” site.

The ALPHA AMINO GROUP of the incoming amino acid at the “A” site carries out a nucleophilic attack on the ESTER group of the peptidy-tRNA at the “P” site.

Question 25

Which of the following statement is not true
Select one:
a. Phospholipids constitute one of the major components of a lipid membrane
b. Glycolipids constitute one of the major components of a lipid membrane
c. Cholesterol constitutes one of the major components of a lipid membrane
d. Triacylglycerols constitute one of the major components of a lipid membrane

Answer 25

d. Triacylglycerols constitute one of the major components of a lipid membrane

Phospholipids constitute one of the major components of a lipid membrane

Question 26

Which of the following statements is false?
Select one:
a. The lagging strand is relicated discontinuously in short pieces of 100-250 nucleotides by DNA polymerase in the 3’ to 5’ direction.
b. The DNA replication is initiated at special sites termed Ori’s to generate replication bubbles.
c. Each strand of the double helix is replicated simultaneously by by somewhat different mechanism.
d. A complex of proteins, including DNA polymerase, replicates the leading strand continuously in the 5’ to 3’ direction.

Answer 26

a. The lagging strand is relicated discontinuously in short pieces of 100-250 nucleotides by DNA polymerase in the 3’ to 5’ direction.
a. The lagging strand is relicated discontinuously in short pieces of 100-250 nucleotides by DNA polymerase in the 5’ to 3’ direction.