Dr. Karthikeyan Pethusamy, a student, and teacher of medical biochemistry shares his teaching slide on molecular biology question & answers.

2. Human diploid genome consists of
a) 2 billion base pairs
b) 3 billion base pairs
c) 5 billion base pairs
d) 6 billion base pairs

4. Human diploid genome consists of
a) 2 billion base pairs
b) 3 billion base pairs
c) 5 billion base pairs
d) 6 billion base pairs
 Haploid
 Diploid

5. Human diploid genome consists of
a)
b)
c)
d) 6 billion base pairs

6. Estimated number of human
genes
a) 20 to 25 thousand
b) 50 thousand
c) 60 thousand
d) 1 lakh

8. Genome of HIV-1

9. Human Genome Project
• The Human Genome Project was initiated by _____________
• The prime objective of HGP was ________________________________
• The private company involved in Human genome sequencing in parallel with HGP
was _____________________
• The first draft of HGP was published in 2001 in the journal _____________
• ____________are the vectors widely used in HGP.
• According to HGP, genetic similarity between all humans is _______________

10. Human Genome Project (1990-
2003)
• The Human Genome Project was initiated by NIH and DOE.
• The prime objective of HGP was to sequence the entire base pairs that makes up
the 24 chromosomes.
• The private company involved in Human genome sequencing in parallel with HGP
was Celera Genomics.
• The first draft of HGP was published in 2001 in the journal “Nature”
• BAC and YAC are the vectors widely used in HGP.
• According to HGP, genetic similarity between all humans is 99.9%.

12. Human genome sequencing is
complete but annotation is yet to be
done.

13. Harper 30 p.102

16. Components of Human genome

17. In the entire human genome, coding
DNA constitute: [AIIMS May 2014]
a. 2%
b. 1%
c. 0.1%
d. 45

21. 30% of human genome is made of repetitive
DNA

24. All are true about microsatellite repeats
EXCEPT
a) Consist of 2 to 6 bp repeated up to 50 times
b) Trinucleotide repeat is the most common
microsatellite DNA
c) Exists as both dispersed and grouped tandem
arrays
d) Number of repeats may vary on the two
chromosomes

26. Our genome is not our own!
Don’t forget
Human genome contains pro-virus!
e.g. ERVW-1

28. Number of genes encoded by
mitochondrial genome
a) 37
b) 47
c) 57
d) 67

29. Mitochondrial DNA is [AIPGMEE 2006]
a) Open circular
b) Closed circular
c) Nicked circular
d) Linear

30. Mitochondrial DNA is
a) Closed circular, diploid
b) Closed circular, haploid
c) Closed circular, polyploid
d) None

31. Which one of the following is the complementary
sequence of 5′ TTAAGCGTAC 3′? [AIPGMEE 2006]
a) 5’ GTACGCTTAA 3′
b) 5’ AATTCGCATG 3’
c) 5’ CATGCGAATT 3’
d) 5’ TTAAGCGTAC 3’

32. Why purine pairs with pyrimidine?
Why purine-purine & pyrimidine-
pyrimidine base pairing is not possible?

34. 5′ TTAAGCGTAC 3′
G 5’

35. 5′ TTAAGCGTAC 3′
TG 5’

36. 5′ TTAAGCGTAC 3′
ATG 5’

37. 5′ TTAAGCGTAC 3′
3’ AATTCGCATG 5’

38. 5′ TTAAGCGTAC 3′
3’ AATTCGCATG 5’
5’ GTACGCTTAA 3′

39. Which one of the following is the complementary
sequence of 5′ TTAAGCGTAC 3′?
a)5’ GTACGCTTAA 3′
b) 5’ AATTCGCATG 3’
c) 5’ CATGCGAATT 3’
d) 5’ TTAAGCGTAC 3’

40. Double stranded RNA exist in
a) A - DNA like conformation
b) B - DNA like conformation
c) Z - DNA like conformation
d) None

43. DNA estimation can be done by
[AIIMS May 2012]
a. Spirometer
b. Spectrophotometer
c. pH meter
d. Sphygmomanometer

44. Hyperchromicity of denaturation

45. DNA gyrase is
a) Eukaryotic DNA topoisomerase I
b) Eukaryotic DNA topoisomerase II
c) Prokaryotic DNA topoisomerase I
d) Prokaryotic DNA topoisomerase II

46. Type I Type II
Makes cut on single strand Makes cut on both strands
ATP is not needed. ATP is needed.
Relaxes negative supercoils in E.
coli;
Both negative and positive in
Eukaryotes.
Relaxes both negative & positive
supercoils. +ve supercoil is
relieved by introducing -ve
supercoils.
Ciprofloxacin & Nalidixic acid are antimicrobial agents as they
inhibit bacterial topoisomerase II (DNA gyrase).
Campothecin & Etoposide are anticancer drugs as they inhibit
human topoisomerase I & II respectively.

47. Supercoiling of DNA

48. Which is NOT true about eukaryotic DNA
ligase?
a) Catalyses the formation of a phosphodiester bond
b) NAD+ is energy source
c) ATP is the energy source
d) Can act only on dsDNA

49. DNA Topoisomerase I

50. DNA ligase

51. After digestion by restriction endonucleases DNA
strands can be joined again by: [AIIMS May 2011]
a. DNA polymerase
b. DNA ligase
c. DNA topoisomerase
d. DNA gyrase

52. Deamination of methylated cytosine
will produce
a) Uracil
b) Thymine
c) Hypoxanthine
d) Adenine

55. Deamination of Adenine

56. Deamination of Adenosine

57. Deamination of cytosine (Non-
enzymatic)

58. Deamination of cytosine
(Enzymatic)

59. Deamination of methylated
cytosine

61. In humans, unmethylated CpG islands
are found in
a) Operator
b) Promoter
c) Introns
d) Exons

65. Which is the most processive DNA
polymerase?
a) DNA Polymerase I
b) DNA Polymerase II
c) DNA Polymerase III
d) None

66. Sliding beta clamp

68. Which is a template independent
DNA polymerase?
a) Poly A polymerase
b) CCA adding enzyme
c) Terminal deoxynucleotidyl transferase
d) Polynucleotide kinase

69. Which is a template independent
DNA polymerase?
a) Poly A polymerase
b) CCA adding enzyme
c) Terminal deoxynucleotidyl transferase
d) Polynucleotide kinase

70. In Eukaryotes, mRNA is produced
by
a) RNA Polymerase I
b) RNA Polymerase II
c) RNA Polymerase III
d) None

73. TRUE about cap0 of mRNA is
a) 7 methyl guanosine attached by 5’5’ thioether
bond
b) 7 methyl guanosine attached by 3’5’
phosphodiester bond
c) 7 methyl guanosine attached by 5’5’
phosphodiester bond
d) 7 methyl guanosine attached by 5’5’ triphosphate
bond

76. Which is NOT true about telomerase?
a) Ribonucleoprotein
b) Reverse transcriptase
c) RNA containing ribozyme
d) Active in cancer cells

78. Restriction enzymes
a) are produced by viruses
b) cut only single stranded DNA
c) can cut the DNA anywhere
d) restrict the expression of viral DNA

82. Isoschizomers & Neoschizomers

83. If a bacteria acquires the gene for only restriction
endonuclease by horizontal transfer [AIPG 10]
a) Bacteria will be able to destroy host DNA
more efficiently
b) Bacteria will die due to methylase deficiency
c) Bacteria will multiply faster
d) Proof reading improved

84. Isoschizomers & Neoschizomers
• Isoschizomers are pairs of restriction enzymes
specific to the same recognition sequence.
• Neoschizomers are a subset of isoschizomers that
recognize the same sequence, but cleave at different
positions from the prototype.

85. DNA glycosylase is involved in
a) Mismatch repair
b) Base excision repair
c) Nucleotide excision repair
d) Direct repair

88. Equivalent of pribnow box in
eukaryotes is
a) Hogness box
b) GC box
c) CAAT box
d) None

90. Eukaryotic
promoter

92. What strategy in transcription factor research allows for the
simultaneous identification of all of the genomic sites bound by a
given transcription factor under a given set of physiological
conditions?
a) Microarray
a) Dnase I sensitivity
b)Chromatin immuno precipitation sequencing (ChIPseq)
c) FISH

93. 466

94. What reactions among transcription proteins greatly
expand the diversity of regulatory factors that can
be generated from a small number of polypeptides?
a) Recombination
b)Homodimerization
c) Heterozygosity & Heterodimerization
d)Trimerization

96. Most eukaryotic transcription factors contain at least
two domains, each of which mediate different aspects
of transcription factor function; these domains are
a) RNA binding domain and repression domain
b) Activation domain and repression domain
c) DNA binding domain and activation domain
d) DNA binding domain and ligand binding domain
e) RNA binding domain and the activation domain

99. The DNA segment from which the
primary mRNA transcript is copied or
transcribed is called
a) Coding strand
b) Initiator methionine domain
c) Translation unit
d) Template strand

101. Which of the forces or interactions listed below play the
predominant role in driving RNA secondary and tertiary
structure formation?
a) Hydrophilic repulsion
b) Formation of complementary base pair regions
c) Hydrophobic interaction
d) Van der Waals interactions
e) Salt bridge formation

103. What is the approximate number of
base pairs associated with a single
nucleosome?
a) 146
b) 292
c) 73
d) 1460
e) 900

105. What is on the 3′ end of all
functional, mature tRNAs?
a) The cloverleaf loop
b) The anticodon
c) The sequence CCA
d) The codon

109. Which of the following cis acting elements
typically resides adjacent to or overlaps with
many prokaryotic promoters?
a) Regulatory gene
b) Structural gene(s)
c) Repressor
d) Operator
e) Terminator

111. HindIII is a restriction endonuclease. Which of the following is most likely to
be the recognition sequence for this enzyme?
a) AAGAAG
b) AAGAGA
c) AAGCTT
d) AAGGAA
e) AAGTTC

113. A physician would like to determine the global patterns of gene
expression in two different types of tumor cells in order to
develop the most appropriate form of chemotherapy for each
patient. Which of the following techniques would be most
appropriate for this purpose?
a) Enzyme linked immunosorbent assay
b) Microarray
c) Northern blot
d) Southern blot
e) Western blot

117. A mutation to this sequence in eukaryotic mRNA
will affect the process by which the 3ʹend polyA tail
is added to the mRNA.
a) AAUAAA
b) CAAT
c) CCA
d) GU… A … AG
e) TATAAA

119. Which of the following eukaryotic
transcription factor recognises the
promoter?
a) Rho
b) Pribnow box
c) Sigma
d) TFIID

120. Which of the following prokaryotic
transcription factor recognises the
promoter?
a) Rho
b) Pribnow box
c) Sigma
d) TFIID

122. Poly A tail is translated into
a) Polylysine
b) Polyglutamate
c) Polyproline
d) None

124. Poly A is translated into
a) Polylysine
b) Polyglutamate
c) Polyproline
d) None

125. A 20-year-old man with a microcytic anemia is found to have
an abnormal form of β globin (Hemoglobin Constant Spring)
that is 172 amino acids long, rather than the 141 found in the
normal protein. Which of the following point mutations is
consistent with this abnormality?
a) CGA → UGA
b) GAU → GAC
c) GCA → GAA
d) UAA → CAA

128. A transfer RNA (tRNA) molecule that is supposed to carry
cysteine (tRNAcys) is mischarged, so that it actually carries
alanine (alatRNAcys). Assuming no correction occurs, what
will be the fate of this alanine residue during protein
synthesis?
a) It will be incorporated into a protein in response to
a codon for alanine.
b) It will be incorporated into a protein in response to
a codon for cysteine.
c) It will be incorporated randomly at any codon.
d) It will remain attached to the tRNA because it
cannot be used for protein synthesis.
e) It will be chemically converted to cysteine by
cellular enzymes

129. The ZYA region of the lac operon
will be maximally expressed if:
a) cyclic AMP levels are low
b) glucose and lactose are both available
c) The attenuation stem–loop is able to form
d) the CAP site is occupied

132. CAP in Lac operon is an example of
[AIPGMEE 07, AIIMS Nov 11]
a) Positive regulator
b) Negative regulator
c) Constitutive expression
d) Attenuation

133. Klenow fragment lacks
a) 5'→3' polymerase
b) 3'→5' exonuclease
c) 5'→3' exonuclease activity
d) None

135. Similarity between DNA
polymerase & Glycogen synthase
a) Both need a primer
b) Both enzymes are processive in adding substrates
c) Either of the above
d) None

136. Basic protein that binds to DNA in
spermatid
a) Histone
b) Protamine
c) Polyamine
d) None

138. Signal recognition particle contains
a) 28S RNA
b) 60S RNA
c) 40S RNA
d) 7S RNA

142. Exact pathophysiology

144. Carboxy terminal domain (CTD) of
RNA polymerase is phosphorylated by
a) TFIID
b) TFIIA
c) TFIIB
d) TFIIH

146. The frequency of transcription is
determined by
a) TATA box
b) Inr element
c) DPE
d) CAAT box

147. Which is NOT a DNA binding
domain?
a) Zinc finger
b) Helix turn Helix
c) Helix loop helix
d) None

149. Sequence of an intron always
starts and ends with
a) GU, AG
b) AG, GU
c) GA, GU
d) UG, AG

151. Splicing activity is a function of [AIIMS May 2010]
a. mRNA
b. snRNA
c. tRNA
d. rRNA

156. Disorders of splicing

157. Group I Self-Splicing is mediated
by
a) Adenosine
b) Guanosine
c) Cytosine
d) None

159. 5S RNA is transcribed by
a) RNA polymerase I
b) RNA polymerase II
c) RNA polymerase III
d) All of the above

162. In mitochondrial mRNA, UGA codes
for
a) Methionine
b) N formyl-methionine
c) Tryptophan
d) None

165. Which is NOT a synonymous codon
pair?
a) CAU & CAC
b) AUU & AUC
c) AUG & AUA
d) AUU & AUC

167. apoB48 & apoB100 production is
due to [AIIMS May 11]
a) alternative splicing
b) mRNA editing
c) alternative polyadenylation
d) mRNA silencing

169. Apo B-48 and Apo B-100 is synthesized from
the same mRNA; the difference between them
is due to [AIIMS May 2011]
a. RNA spicing
b. Allelic exclusion
c. Deamination of cytidine to uracil
d. Upstream repression

170. During translation, initiator tRNA
binds to
a) A site
b) P site
c) E site
d) None

172. P – bodies are
a) present in the nucleus
b) the site of protein synthesis
c) the sites of translation repression
d) exclusively involved in the destruction of RNA

175. The molecular mechanism behind the
alternative production of membrane
bound and secretory IgM is
a) Allelic exclusion
b) Somatic hypermutation
c) Class switching
d) Alternate polyadenylation

177. Molecular mechanism responsible for
affinity maturation of antibodies is
a) Somatic hypermutation
b) RNA editing
c) RNA splicing
d) Allelic exclusion

179. The molecular mechanism behind T cells
expressing only one type of T cell receptor
is
a) Allelic exclusion
b) Somatic hypermutation
c) Class switching
d) Alternate polyadenylation