Question

Which of the following reactions requires an energy source? Y for Yes and N for No.

A) relaxation of tension in DNA upstream of a replication fork by topoisomerase I.

B) unwinding dsDNA by DNA helicase during DNA replication.

C) peptide bond formation.

D) synthesis of DNA by DNA polymerase.

E) ligation of the sugar-phosphate backbone in DNA by DNA ligase.

Group of answer choices

A) N, B) Y, C) N, D) N, E) Y

A) N, B) Y, C) Y, D) Y, E) Y

A) N, B) N, C) Y, D) Y, E) Y

A) Y, B) Y, C) Y, D) Y, E) Y

Answer 1

The right answer is N,Y,Y,Y,Y

there is no energy requirement during the removal of negative supercoiling by DNA topoisomerase1 as it cleaves one DNA strand pass it over and then religates.The peptide bond formation reaction requires energy as this is an unfavourable reaction ie formation of dipeptide.Unwinding of DNA requires the strands to be melted by breking of the hydrogen bonds so energy is required.Ligation reuires energy in the form of ATP for joining the oligonucleotides.The right answer is option B)