Chapter 12, Problem 17A

Summary Introduction

To explain:

The enzymes used in DNA replication and describe their function.

Introduction:

DNA replication a process by which DNA makes copies of itself and this process requires lots of enzymes. DNA replication occurs in three stages namely, Initiation, Elongation, and Termination.

Explanation of Solution

Initiation: During initiation, a short piece of RNA known as RNA primer, bind to one of the strands of DNA called leading strand, and this acts as starting point for DNA synthesis.

Elongation: During the elongation process, DNA polymerase binds to the leading strand of DNA and synthesizes the new DNA by pairing bases of template strands to their complementary bases. Replication on leading strand is continuous while on the lagging strand, it is discontinuous and occurs in fragments, known as okazaki fragments.

Termination: The process of expanding the new DNA strands continues until there is either no more DNA template left to replicate.The okazaki fragments are then joined by the enzyme DNA ligase.

The enzymes use in DNA replication are the following:

DNA helicase: It unwinds the DNA by breaking hydrogen bonds.

RNA primer or primase: It initiates the replication process.

DNA polymerase: It synthesizes new DNA strand by joining base pairs to the template strand.

DNA ligase: It joins the Okazaki fragments.

DNA gyrase: It releases or reduces the strain during unwinding of the DNA.