In E. coli, the gene dnaQ encodes the subunitof the DNA polymerase III core enzy

Question

In E. coli, the gene dnaQ encodes the subunitof the DNA polymerase III core enzyme that has
3'---->5' exonuclease activity. As you might expect, the E. colicarrying mutations in this gene...

A. are not able to remove RNA primers during DNA replication
B.accumulate new mutations at a high rate
C.synthesize new DNA very slowly
D. are not able to initiate replication at oriC
E.are not able to repair the nicks between the neighboring Okazakiframents

I need a complete explanation why its that answer

Plz tell me how convinced you are about the answer. Thanks alot! In E. coli, the gene dnaQ encodes the subunitof the DNA polymerase III core enzyme that has
3'---->5' exonuclease activity. As you might expect, the E. colicarrying mutations in this gene...

A. are not able to remove RNA primers during DNA replication
B.accumulate new mutations at a high rate
C.synthesize new DNA very slowly
D. are not able to initiate replication at oriC
E.are not able to repair the nicks between the neighboring Okazakiframents

I need a complete explanation why its that answer

Plz tell me how convinced you are about the answer. Thanks alot!

Explanation / Answer

             B. accumulates new mutations at ahigh rate.            Thisis because, 3' - 5' exonuclease activity is concerned with proofreading and exonuclease function             Whenthis function is impaired due to a mutation, it cannot edit theincorrect DNA that is incorporated during the             synthesisand hence new mutations are accumulated at very high rate.            DNA pol-III has only 3' - 5' activity and does not have 5' - 3'activity.             Primersare removed by 5' - 3' exonuclease activity of DNA polymerase andnot by 3' - 5' activity.             Henceoption A is ruled out.             Thesynthesis of DNA by DNA pol-III is carried out by its subunit which is encoded by the gene polC (dnaE).             Hereas the mutation is concerned with dnaQ, it has nothing to dowith the synthesis of DNA.             Henceoption C is also ruled out.             Theinitiation of replication is carried out by dnaA, dnaB and dnaCproteins and DNA pol-III has nothing to do             withinitiation.             Oncethe initiation of DNA has occurred, DNA pol-III helps in theelongation but has no role to play initiation.             Hencethis option is also ruled out that is option D.             Nickrepair in between the neighboring okazaki fragments is carried outby 5'-3' exonuclease acivity of DNA pol-I.             AsDNA pol-III lacks this 5'-3' exonuclease acivity this nick repairis not carried out.             Henceoption E is also ruled out.          Hope youare satisfied with the answer.

Related Questions

Navigate

• Browse (All)
• Browse I
• Subjects

---