Homework Help

Why does a primer need to be supplied before DNA template can be copied?This is...

user profile pic

rawrhappy | Student, Grade 10 | Honors

Posted February 8, 2013 at 3:02 AM via web

dislike 0 like

Why does a primer need to be supplied before DNA template can be copied?

This is involving DNA Replication.

1 Answer | Add Yours

user profile pic

orchid101 | College Teacher | (Level 1) Associate Educator

Posted May 15, 2013 at 2:28 PM (Answer #1)

dislike 1 like

Initiation of DNA synthesis requires an RNA primer. DNA polymerases cannot initiate DNA chains de novo. (RNA polymerase, in contrast, can initiate chains de novo during trascription). A pre-existing polynucleotide chain (the primer) is required to which polynucleotides are added. The primer RNA is a short polynucleotide chain with a 5' triphosphate end and a 3'-OH end. The RNA primer is synthesized by the DNA template close to the origin of replication. This synthesis is probably catalysed by a modified RNA polymerase which may contain a starting factor. In E. coli RNA  polymerase is required just before replication of DNA, but protein synthesis is not.

Join to answer this question

Join a community of thousands of dedicated teachers and students.

Join eNotes