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NUCLEIC ACIDS- Part 13
See all quizzes of NUCLEIC ACIDS- Part 13 here:
1 After formation of a peptide bond, mRNA
is translocated along the ribosome by
(A) eEF-1 and GTP
(B) eEF-2 and GTP
(C) Peptidyl transferase and GTP
(D) Peptidyl transferase and ATP
2. Binding of formylmehtionyl tRNA to 30 S
ribosomal subunit of prokaryotes is
inhibited by
(A) Streptomycin (B) Chloramphenicol
(C) Erythromycin (D) Mitomycin
3. Tetracyclines inhibit binding of amino acyl
tRNAs to
(A) 30 S ribosomal subunits
(B) 40 S ribosomal subunits
(C) 50 S ribosomal subunits
(D) 60 S ribosomal subunits
4. Peptidyl transferase activity of 50 S
ribosomal subunits is inhibited by
(A) Rifampicin (B) Cycloheximide
(C) Chloramphenicol (D) Erythromycin
5. Erythromycin binds to 50 S ribosomal sub
unit and
(A) Inhibits binding of amino acyl tRNA
(B) Inhibits Peptidyl transferase activity
(C) Inhibits translocation
(D) Causes premature chain termination
6. Puromycin causes premature chain
termination in
(A) Prokaryotes (B) Eukaryotes
(C) Both (A) and (B) (D) None of these
7. Diphtheria toxin inhibits
(A) Prokaryotic EF-1 (B) Prokaryotic EF-2
(C) Eukaryotic EF-1 (D) Eukaryotic EF-2
8. The proteins destined to be transported
out of the cell have all the following features
except
(A) They possess a signal sequence
(B) Ribosomes synthesizing them are bound to
endoplasmic reticulum
(C) After synthesis, they are delivered into Golgi
apparatus
(D) They are tagged with ubiquitin
9. SRP receptors involved in protein export
are present on
(A) Ribosomes
(B) Endoplasmic reticulum
(C) Golgi appartus
(D) Cell membrane
10. The signal sequence of proteins is cleaved
off
(A) On the ribosomes immediately after synthesis
(B) In the endoplasmic reticulum
(C) During processing in Golgi apparatus
(D) During passage through the cell membrane
11. The half-life of a protein depends upon its
(A) Signal sequence
(B) N-terminus amino acid
(C) C-terminus amino acid
(D) Prosthetic group
12. Besides structural genes that encode
proteins, DNA contains some regulatory
sequences which are known as
(A) Operons (B) Cistrons
(C) Cis-acting elements (D) Trans-acting factors
13. Inducers and repressors are
(A) Enhancer and silencer elements respectively
(B) Trans-acting factors
NUCLEIC ACIDS 259
(C) Cis-acting elements
(D) Regulatory proteins
14. cis-acting elements include
(A) Steroid hormones (B) Calcitriol
(C) Histones (D) Silencers
15. Silencer elements
(A) Are trans-acting factors
(B) Are present between promoters and the
structural genes
(C) Decrease the expression of some structural
genes
(D) Encode specific repressor proteins
16. trans-acting factors include
(A) Promoters (B) Repressors
(C) Enhancers (D) Silencers
17. Enhancer elements have all the following
features except
(A) They increase gene expression through a
promoter
(B) Each enhancer activates a specific promoter
(C) They may be located far away from the
promoter
(D) They may be upstream or downstream from
the promoter
18. Amplification of dihydrofolate reductase
gene may be brought about by
(A) High concentrations of folic acid
(B) Deficiency of folic acid
(C) Low concentration of thymidylate
(D) Amethopterin
19. Proteins which interact with DNA and
affect the rate of transcription possess the
following structural motif:
(A) Helix-turn-helix motif
(B) Zinc finger motif
(C) Leucine zipper motif
(D) All of these
20. Lac operon is a cluster of genes present in
(A) Human beings (B) E. coli
(C) Lambda phage (D) All of these
21. Lac operon is a cluster of
(A) Three structural genes
(B) Three structural genes and their promoter
(C) A regulatory gene, an operator and a
promoter
(D) A regulatory gene, an operator, a promoter
and three structural genes
22. The regulatory i gene of lac operon
(A) Is inhibited by lacotse
(B) Is inhibited by its own product, the repressor
protein
(C) Forms a regulatory protein which increases
the expression of downstream structural genes
(D) Is constitutively expressed
23. RNA polymerase holoenzyme binds to lac
operon at the following site:
(A) i gene (B) z gene
(C) Operator locus (D) Promoter region
24. Trancription of z, y and a genes of lac
operon is prevented by
(A) Lactose (B) Allo-lactose
(C) Repressor (D) cAMP
25. Transcription of structural genes of lac
operon is prevented by binding of the
repressor tetramer to
(A) i gene (B) Operator locus
(C) Promoter (D) z gene
26. The enzymes encoded by z, y and a genes
of lac operon are inducible, and their
inducer is
(A) Lactose
(B) Allo-lactose
(C) Catabolite gene activator protein
(D) All of these
27. Binding of RNA polymerase holoenzyme
to the promoter region of lac operon is
facilitated by
(A) Catabolite gene activator protein (CAP)
(B) cAMP
(C) CAP-cAMP complex
(D) None of these
28. Lactose or its analogues act as positive
regulators of lac operon by
(A) Attaching to i gene and preventing its
expression
(B) Increasing the synthesis of catabolite gene
activator protein
(C) Attaching to promoter region and facilitating
the binding of RNA polymerase holoenzyme
(D) Binding to repressor subunits so that the
repressor cannot attach to the operator locus
29. Expression of structural genes of lac operon
is affected by all the following except
(A) Lactose or its analogues
(B) Repressor tetramer
(C) cAMP
(D) CAP-cAMP complex
30. The coding sequences in lac operon
include
(A) i gene
(B) i gene, operator locus and promoter
(C) z, y and a genes
(D) i, z, y and a genes
