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NUCLEIC ACIDS- Part 5
See all quizzes of NUCLEIC ACIDS- Part 5 here:
1. Initiation of protein synthesis begins with
binding of
(A) 40S ribosomal unit on mRNA
(B) 60S ribosomal unit
(C) Charging of tRNA with specific amino acid
(D) Attachment of aminoacyl tRNA on mRNA
2. Initiation of protein synthesis requires
(A) ATP (B) AMP
(C) GDP (D) GTP
3. The enzyme amino acyl tRNA synthetase
is involved in
(A) Dissociation of discharged tRNA from 80S
ribosome
(B) Charging of tRNA with specific amino acids
(C) Termination of protein synthesis
(D) Nucleophilic attack on esterified carboxyl
group of peptidyl tRNA
4. In the process of activation of amino acids
for protein synthesis, the number of high
energy phosphate bond equivalent
utilised is
(A) 0 (B) 1
(C) 2 (D) 4
5 Translation results in a product known as
(A) Protein (B) tRNA
(C) mRNA (D) rRNA
6. In the process of elongation of chain
binding of amino acyl tRNA to the A site
requires
(A) A proper codon recognition
(B) GTP
(C) EF-II
(D) GDP
7. The newly entering amino acyl tRNA into
A site requires
(A) EF-II (B) Ribosomal RNA
(C) mRNA (D) EF-I
8. The α-amino group of the new amino acyl
tRNA in the A site carries out a nucleophilic
attack on the esterified carboxyl
group of the peptidyl tRNA occupying the
P site. This reaction is catalysed by
(A) DNA polymerase
(B) RNA polymerase
(C) Peptidyl transferase
(D) DNA ligase
9. The nucleophilic attack on the esterified
carboxyl group of the peptidyl-tRNA
occupying the P site and the α-amino
group of the new amino acyl tRNA, the
number of ATP required by the amino acid
on the charged tRNA is
(A) Zero (B) One
(C) Two (D) Four
10. Translocation of the newly formed
peptidyl tRNA at the A site into the empty
P site involves
(A) EF-II, GTP
(B) EF-I, GTP
(C) EF-I, GDP
(D) Peptidyl transferase, GTP
11. In eukaryotic cells
(A) Formylated tRNA is important for initiation of
translation
(B) Cyclohexamide blocks elongation during
translation
(C) Cytosolic ribosomes are smaller than those
found in prokaryotes
(D) Erythromycin inhibits elongation during
translation
12. The mushroom poison amanitin is an
inhibitor of
(A) Protein synthesis (B) mRNA synthesis
(C) DNA synthesis (D) Adenosine synthesis
13. Tetracylin prevents synthesis of polypeptide
by
(A) Blocking mRNA formation from DNA
(B) Releasing peptides from mRNA-tRNA complex
(C) Competing with mRNA for ribosomal binding
sites
(D) Preventing binding of aminoacyl tRNA
14. In prokaryotes, chloramphenicol
(A) Causes premature release of the polypeptide
chain
(B) Causes misreading of the mRNA
(C) Depolymerises DNA
(D) Inhibits peptidyl transferase activity
15 Streptomycin prevents synthesis of polypeptide
by
(A) Inhibiting initiation process
(B) Releasing premature polypeptide
(C) Inhibiting peptidyl transferase activity
(D) Inhibiting translocation
16. Erythromycin acts on ribosomes and inhibit
(A) Formation of initiation complex
(B) Binding of aminoacyl tRNA
(C) Peptidyl transferase activity
(D) Translocation
17. The binding of prokaryotic DNA dependent
RNA polymerase to promoter sites
of genes is inhibited by the antibiotic:
(A) Puromycin (B) Rifamycin
(C) Terramycin (D) Streptomycin
18. The gene which is transcribed during
repression is
(A) Structural (B) Regulator
(C) Promoter (D) Operator
19 The gene of lac operon which has constitutive
expression is
(A) i (B) c
(C) z (D) p
20. The minimum effective size of an operator
for lac repressor binding is
(A) 5 base pairs (B) 10 base pairs
(C) 15 base pairs (D) 17 base pairs
21 To commence structural gene transcription
the region which should be free on
lac operation is
(A) Promoter site (B) Operator locus
(C) Y gene (D) A gene
22. In the lac operon concept, a protein molecule
is
(A) Operator (B) Inducer
(C) Promoter (D) Repressor
23. The catabolite repression is mediated by
a catabolite gene activator protein (CAP)
in conjunction with
(A) AMP (B) GMP
(C) cAMP (D) Cgmp
24. The enzyme DNA ligase
(A) Introduces superhelical twists
(B) Connects the end of two DNA chains
(C) Unwinds the double helix
(D) Synthesises RNA primers
25. Restriction endonucleases
(A) Cut RNA chains at specific locations
(B) Excise introns from hnRNA
(C) Remove Okazaki fragments
(D) Act as defensive enzymes to protect the host
bacterial DNA from DNA of foreign organisms
26. The most likely lethal mutation is
(A) Substitution of adenine for cytosine
(B) Insertion of one nucleotide
(C) Deletion of three nucleotides
(D) Substitution of cytosine for guanine
27. In the following partial sequence of
mRNA, a mutation of the template DNA
results in a change in codon 91 to UAA.
The type of mutation is
88 89 90 91 92 93 94
GUC GAC CAG UAG GGC UAA CCG
(A) Missene (B) Silent
(C) Nonsense (D) Frame shit
28. Restriction endonucleases recognize and
cut a certain sequence of
(A) Single stranded DNA
(B) Double stranded DNA
(C) RNA
(D) Protein
29. Positive control of induction is best
described as a control system in which an
operon functions
(A) Unless it is switched off by a derepressed
repressor protein
(B) Only after a repressor protein is inactivated
by an inducer
(C) Only after an inducer protein, which can be
inactivated by a corepressor, switches it on
(D) Only after an inducer protein, which is
activated by an inducer, switch it on
30. Interferon
(A) Is virus specific
(B) Is a bacterial product
(C) Is a synthetic antiviral agent
(D) Requires expression of cellular genes
