The following sequence of DNA is transcribed and encodes a s

The following sequence of DNA is transcribed and encodes a small protein with the sequence Met Tyr Arg Gly Ala. 5\'-CCTATGCCCGCATCATTACGCACCTCTGTACATGGC-3\' 3\'-GGATACGGGCGTAGTAATGCGTGGAGACATGTACCC-5\' Which strand of DNA is the template strand for transcription? Which direction (right to left or left to right) does RNA polymerase move along the template as it transcribes this gene? What is the sequence of the nucleotides in the processed mRNA molecule for this gene? Indicate the 5\' and3\' directions of this gene. A single base mutation in the gene results in synthesis of the peptide Met Tyr. What is the sequence of nucleotides making up the mRNA produced by this mutant gene? List three characteristics of the genetic code. How can you distinguish experimentally among DNA polymerase III, RNA polymerase, and primase? Suppose you isolate a mutant bacterium that does not have an active ligase enzyme. Can this bacterium replicate? Why or why not? At what step will replication be halted?

Solution

1.

a)The template strand is:

3\' -GGA.........................................CCC5\'

The RNA polymerase moves from left to right i.e from 3\' end of the template strand.

b).mRNA sequence is:

5\' CCU AUG CCC GCA UCA UUA CGC ACC UCU GUA CAU GGG 3\'

c)The sequence of nucleotides making up the mRNA will be AUG UAU

2. Three characteristics of genetic code are:

3.

4.No the bacteria cannot replicate.Ligase enzyme helps in the joining of DNA fragements after repair and also in joining the Okazaki fragments.Replication will thus be halted in the repair stage and during synthesis of lagging strand of DNA.