A 6.4 Kb plasmid DNA has two restriction endonuclease sites, HindIII and EcoRI. Complete double digestion of the plasmid with both the enzymes yields two fragments of 3.1 and 3.3 Kb. In order to study DNA repair process, a G:T mismatch was introduced in one strand of HindIII site and the damaged plasmid was incubated in a reconstituted repair system containing all the factors and enzymes required for repair. If the efficiency of the repair system is 50%, which one of the following band patterns on agarose gel will be obtained after treating the repaired plasmid with both HindIII and EcoRI?

The following statements are made on DNA replication: 

A. Replication fork is a branch point in a replication 'eye' or 'bubble'.

B. A replication bubble contains two replication forks.

C. DNA replication is continuous according to the interpretation made by Okazaki.

D. Multiple priming events are required for both leading and lagging strands to initiate DNA synthesis.

Which one of the following is the correct combination?

• A and B

• B and C

• C and D

• A and C

Satellite RNAs (sat-RNAs) are species of RNA associated with specific strains of some plant RNA viruses, although it is not necessary for their replication.

Few statements are given below on sat-RNA.

A. Presence of sat-RNA leads to reduction in severity of disease symptoms.

B. Presence of sat-RNA leads to increase in severity of disease symptoms.

C. sat-RNA is constitutively expressed like coat proteins and is independent of virus infection.

D. sat-RNA is not constitutively expressed like coat proteins but is expressed only after virus infection.

Which one of the following combinations of above statements regarding sat-RNA only after virus infection?

• A and B

• B and C

• C and D

• A and D

A chromatin immunoprecipitation (ChIP) assay was performed to determine specific transcription factor binding sites on the promoter of a gene. Pull down was done using either IgG or anti-bodies against c-myc. A DNA containing c-myc binding regions was used as a control for PCR amplification (input). Which one of the following PCR representations of DNA is correct?

75.

Following are certain statements related to eukaryotic DNA replication:

A. The genome of multicellular animals contain many potential origins of replication.

B. During early development, when embryos are undergoing rapid cell divisions, origin sites are uniformly activated.

C. "Pulse-chase" technique is used to label sites of DNA replication.

D. The rate of elongation of different DNA chains during genome replication varies drastically.

Which one of the following combinations of above statements is correct?

• A, B and C

• A, C and D

• B, C and D

• A, B and D

Puromycin is an antibiotic used to inhibit protein synthesis. Given below are few statements about the antibiotic.

A. It enters the E-site of the ribosome where it prevents the release of deacetylated tRNA after the action of peptidyl transferase.

B. It blocks the translocation process by binding to the translocation factor EF-G.

C. Puromycin resembles the initiator tRNA, tRNA_i^t-met and binds exclusively to the P-site.

D. It resembles the aminoacylt tRNA and binds to the A-site of the ribosome,

E. Puromycin inhibits only prokaryotic protein synthesis.

F. Puromycin inhibits both prokaryotic and eukaryotic protein synthesis.

Which of the above statement(s) is/ are true?

• A and E

• B only

• D and F

• C and E

A gene producing red pigment was placed near centromeres of fission yeast and thus subjected to position effect variegation and produced white colonies. A screen for mutants that increased the red pigment production was undertaken. Which of the following genes, when mutated, is likely to produce this genotype?

• Histone deacetylase

• Histone acetylase

• RNA polymerase II

• TATA binding factor

DNA is not hydrolzed by alkali whereas RNA is readily hydrolyzed. This is due to 

• The double helical structure of DNA.

• The presence of uridine in RNA.

• Due to features observed in RNA such as stem-loop structures.

• The presence of 2'-OH group in RNA

Which one of the following statements about eukaryotic translation is NOT true? In eukaryotic translation,

• ribosome binding site on mRNA is called Kozak consensus sequences.

• initiator tRNA is tRNA_i^f-met.

• initiator amino acid is methionine.

• translocation factor is eEF2.

During replication, the RNA primer is degraded by the 5'-3' exonuclease activity of

• RNase H1 (ribonuclease H1)

• FEN-1 (flap endonuclease 1)

• Topoisomerase II B

• DNA polymerase γ