JIPMER Practice Quiz

Question 1

In the Meselson and Stahl experiment, after E. coli grown for many generations in 15N medium were shifted to 14N medium and allowed to divide for two generations, what pattern of DNA bands would be expected on CsCl density gradient centrifugation if DNA replication is semiconservative?

Accepted Answer

One intermediate band and one light band

Question 2

Which enzyme catalyzes the joining of Okazaki fragments during DNA replication?

Accepted Answer

DNA ligase

Question 3

Which feature distinguishes eukaryotic mRNA processing from prokaryotic gene expression?

Accepted Answer

Addition of 5' cap and 3' poly-A tail to primary transcript

Question 4

In the Hershey-Chase experiment, why was 32P used to label DNA and 35S used to label protein?

Accepted Answer

DNA contains phosphorus but not sulfur, while many proteins contain sulfur but not phosphorus in their backbone

Question 5

In a transcription unit, the template strand is the DNA strand that:

Accepted Answer

Is read by RNA polymerase in the 3' → 5' direction