Identify the role of deoxyribonucleoside triphosphates in DNA replication?
Answer & explanation
Correct answer: option 1
The correct answer is Option (1) → To provide energy for the process of replication
Option (1) To provide energy for the process of replication — Correct. Deoxyribonucleoside triphosphates are the building blocks of the new DNA strand. They also provide the energy for joining the nucleotides, because each one carries two extra phosphates, like ATP.
Option (2) To bind to sigma factor — Incorrect. The sigma factor is part of RNA polymerase in transcription, where it helps recognise the promoter. It has no role in DNA replication.
Option (3) To activate the enzyme ligase — Incorrect. DNA ligase joins the short Okazaki fragments on the lagging strand. Deoxyribonucleoside triphosphates are substrates and the energy source for adding nucleotides; they do not activate ligase.
Option (4) To initiate replication fork — Incorrect. Replication starts at the origin of replication, where the DNA unwinds to form the replication fork. The deoxyribonucleoside triphosphates serve as substrates and provide energy, but they do not start the fork.
NCERT Extract:
The Machinery and the Enzymes – “… Furthermore, energetically replication is a very expensive process. Deoxyribonucleoside triphosphates serve dual purposes. In addition to acting as substrates, they provide energy for polymerisation reaction (the two terminal phosphates in a deoxynucleoside triphosphates are high-energy phosphates, same as in case of ATP).”