Question

A biochemist isolates, purifies, and combines in a test tube a variety of molecules needed for DNA replication. When she adds some DNA to the mixture, replication occurs, but each DNA molecule consists of a normal strand paired with numerous segments of DNA a few hundred nucleotides long. What has she probably left out of the mixture?a. DNA ligase

b. nucleotides
c. DNA polymerase III
d. Okazaki fragments

Answer 1

a. DNA ligase

Step-by-step explanation:

DNA ligase is the enzyme of DNA replication that joins DNA segments together by catalyzing the formation of new phosphodiester bonds. These reactions use the energy of ATP molecules to form the bonds. The function of the DNA ligase enzyme is to join the Okazaki fragments together which in turn are formed during replication of the lagging strand. In the absence of DNA ligase, the Okazaki fragments cannot be joined together.

According to the given information, the process of DNA replication obtained shorts DNA segments of a few hundred nucleotides. This means that the reaction mixture lacked the DNA ligase enzyme and the DNA segments could not be joined together.