Question

a student isolates, purifies, and combines in a test tube a variety of molecules needed for dna replication. after adding 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 the student probably left out of the mixture?

○ dna polymerase

○ dna ligase

○ okazaki fragments

○ primase

Explanation:

In DNA replication, the lagging strand is synthesized as Okazaki fragments (short DNA segments). DNA ligase is responsible for joining these Okazaki fragments into a continuous strand. The student’s DNA has normal strands paired with short segments, meaning the fragments aren’t joined. DNA polymerase synthesizes DNA, primase makes primers, and Okazaki fragments are the products (not an ingredient left out). So the missing component is DNA ligase.

Answer:

B. DNA ligase