Target Exam

CUET

Subject

Biology

Chapter

Molecular Basis of Inheritance

Question:

Identify the role of deoxyribonucleoside triphosphates in DNA replication?

Options:

To provide energy for the process of replication

To bind to sigma factor

To activate the enzyme ligase

To initiate replication fork

Correct Answer:

To provide energy for the process of replication

Explanation:

The correct answer is Option (1) → To provide energy for the process of replication

In living cells, such as E. coli, the process of replication requires a set of catalysts (enzymes). The main enzyme is referred to as DNA-dependent DNA polymerase, since it uses a DNA template to catalyse the polymerisation of deoxynucleotides. These enzymes are highly efficient enzymes as they have to catalyse polymerisation of a large number of nucleotides in a very short time. E. coli that has only 4.6 × 106 bp (compare it with human whose diploid content is 6.6 × 109 bp), completes the process of replication within 18 minutes; that means the average rate of polymerisation has to be approximately 2000 bp per second. Not only do these polymerases have to be fast, but they also have to catalyse the reaction with high degree of accuracy. Any mistake during replication would result into mutations. 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).