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 polymerase
B) DNA ligase
C) nucleotides
D) Okazaki fragments
E) primase

Answer 1

DNA replication requires a few things:

1. a template

2. DNA polymerase

3. some sort of primer which binds to the DNA to get it started

4. oligonucleotides (to add as the replication occurs)

5. a ligase to complete any fragmented DNA

So, if the biochemist added some stuff but doesn't really get replication to occcur, he/she probably left out the DNA ligase