Zoology - Molecular Basis of Inheritance Question with Solution | TestHub
Which of these is the correct function of enzymes/protein used in DNA replication?
| Helicase | Topoisomerase | Single-strand binding protein | DNA polymerase | |
| I. | Adds DNA nucleotides to the 3'end of a growing polynucleotide strand | prevents original strand reforming complementary base pairs | releases the tension caused by unwinding | makes strands available as templates |
| II. | releases the tension caused by unwinding | prevents original strands from reforming complementary base pairs | makes strands available as templates | adds DNA nucleotides to the 3'end of a growing polynucleotide strand |
| III. | releases the tension caused by unwinding | makes strands available as templates | adds DNA nucleotides to the 3'end of a growing polynucleotide strand | prevents original strands from reformingcomplementary base pairs |
| IV. | makes strands available as templates | releases the tension caused by unwinding | prevents original strands from reforming complementary base pairs | adds DNA nucleotides to the 3'end of a growing polynucleotide strand |
Options:
Answer:
Solution:
DNA replication is semiconservative. DNA is made by enzymes called DNA polymerases. DNA replication requires other enzymes including DNA primase, DNA helicase, DNA ligase, and topoisomerase. DNA polymerases are responsible for synthesizing DNA: they add nucleotides one by one to the growing DNA chain that are complementary to the template strand. Helicase's job is to move the replication forks forward by "unwinding" the DNA. It does so by breaking the hydrogen bonds between the nitrogenous base pairs.
Single-strand binding proteins coat the separated strands of DNA near the replication fork preventing the cut strands from coming back together into a double helix. Topoisomerase enzyme prevents the DNA double helix ahead of the replication fork from getting too tightly wound as the DNA is opened up.
