BCHEM/IV/EC/07 Student's Copy
2 0 1 8
CBCS
4th Semester
BIOCHEMISTRY
Paper BC-4
Molecular Biology
Full Marks 75
Time 3 Hours
PART A—OBJECTIVE
Marks 25
The figures in the margin indicate full marks for the questions
SECTION—A
Marks 10
Tick the correct answer in the brackets provided 1×10=10
1. Which of the following is not true for DNA replication in prokaryotes?
Runs in 3¢ to 5¢ direction
Requires a primer
Catalyzed by DNA polymerases
Semi-conservative in nature
2. The enzymes which bind to the replication fork causing unwinding of the
DNA double helix is
DNA polymerase
primase
topoisomerase
DNA helicase
/348 1 Contd.
3. The sigma factor of RNA polymerase is responsible for
synthesizing RNA strand in 5¢ to 3¢ direction
termination of transcription
recognition of promoter region
enzyme assembly
4. The Pribnow box in the promoter region of prokaryotic genes has the
sequence
TTGACA
TATAG
GACAT
TATAAAT
5. Which of the following is not true regarding the genetic code?
Degenerate
Ambiguous
Non-overlapping
Universal
6. Degeneracy of genetic code denotes
single-codon stands for multiple amino acids
one amino acid is represented by multiple codons
overlapping of codons is observed at times
some codons contain four bases instead of three
7. Translation takes place in
cytoplasm
mitochondria
lysosomes
ribosomes
8. The Shine-Dalgarno sequence in mRNA is complementary to a sequence in
16S rRNA
5S rRNA
5·8S rRNA
23S rRNA
BCHEM/IV/EC/07/348 2 Contd.
9. The extra-chromosomal, circular, double-stranded DNA found in some
prokaryotes which can be used as vectors are called
phages
yeast artificial chromosomes
plasmids
cosmids
10. Hybridoma technology is a method adopted to create
monoclonal antibodies
polyclonal antibodies
restriction endonucleases
recombinant DNA
SECTION—B
Marks 15
Write short notes on the following 3×5=15
1. Meselson and Stahl experiment
OR
Types of DNA replication
2. 5¢ capping of mRNA
OR
Rho-independent termination of transcription
3. Wobble hypothesis
OR
Significance of degeneracy
4. Charged tRNA
OR
Termination of translation in prokaryotes
5. Plasmids
OR
Restriction endonucleases
BCHEM/IV/EC/07/348 3 Contd.
PART B—DESCRIPTIVE
Marks 50
The figures in the margin indicate full marks for the questions
1. Explain in detail the mechanism of DNA replication in prokaryotes. 10
OR
Write short notes on the following 5+5=10
Hershey and Chase experiment
DNA polymerases
2. What is called 'the central dogma in molecular biology'? Explain the
initiation and elongation steps for transcription in prokaryotes.

OR
Write notes on the following 6+4=10
Reverse transcriptase
Polyadenylation in mRNA
3. Discuss in detail the Lac Operon model for E. coli. 10
OR
Write notes on the following 5+5=10
Tryptophan Operon
Basic features of the genetic code
4. Write a detailed note on the initiation and elongation steps of
translation in prokaryotes. 5+5=10
OR
Write notes on the following 5+5=10
Structure of ribosome
Inhibitors of translation
5. What are the steps involved in recombinant DNA technology? 10
OR
Write notes on the following 5+5=10
Phases
Monoclonal antibody production