Question

Indicate whether the following statements are true for DNA replication only (type DNA next to the statement), RNA transcription only (type RNA next to the statement); both replication and transcription (type BOTH next to the statement); or neither replication or transcription (type NONE next to the statement). (10 points, 2 points each) A. The new strand is synthesized in the 3' to 5' direction. B. A primer is required C. A template is required. D. Polymerases bind to unique sites called "origins." E. Polymerases bind to unique sites called "promoters." F. Uncorrected errors result in mutation.

Answer 1

Answer :

A. A new strand is synthesised in the 3' to 5; direction. NONE : Beacuse both the DNA and RNA strands are synthesisized in the 5' to 3' direction only.

B. A Primer is required : DNA replication only : Due to the fact that all known DNA polymerases requires a primer with an exposed 3' OH group for polymerization. Primer provides this exposed OH group to which nucleotides are added by DNA polymerases.  

C. A template is required : BOTH : Both replication and transcription requires templates. But the difference is, in replication, Both the strands acts as templates whereas in transcription only one strand acts as template.

D. Polymerase binds to unique sites known as origins : DNA : DNA polymerases both in prokaryotes and Eukaryotes binds to specific sequences called origin sites, from which the replication begins. These origin sites are called as Ori C sites in prokaryotes, Autonomously replicating sequences in eukaryotes.

E. Polymerases binds to unique sites called promoters : RNA: Transcription both in prokaryotes and in eukaryotes begins only when RNA polymerase binds to specific sequences called promoters, which acts as binding sites for transcription factors as well as RNA polymerases.

F. Uncorrected errors results in mutations : DNA : Since DNA is the heritable genetic material, any mistakes/errors during DNA replication can lead to mutations. However, there are repair mechanisms both on bacterial and eukaryotic systems to proofread/correct these misincorporations occured during replication.