Though this question sucks, which enzyme elongates the new DNA strand starting at an RNA primer?
A.DNA polymerase I
B.DNA polymerase III
C.DNA polymerase II
D.DNA ligase
E.RNA polymerase
To determine which enzyme elongates the new DNA strand starting at an RNA primer, we need to understand the process of DNA replication and the function of each of the enzymes mentioned in the options.
During DNA replication, the parental DNA strands separate, and each strand serves as a template for the synthesis of a new complementary strand. The synthesis of the new DNA strand is carried out by DNA polymerases, which are enzymes responsible for catalyzing the addition of nucleotides to the growing DNA chain.
Out of the options provided:
A. DNA polymerase I: This enzyme is involved in removing RNA primers and replacing them with DNA nucleotides during the process of DNA replication. It does not elongate the new DNA strand starting at an RNA primer.
B. DNA polymerase III: This enzyme is the main DNA polymerase responsible for the synthesis and elongation of new DNA strands during DNA replication. It elongates the new DNA strand starting at an RNA primer.
C. DNA polymerase II: This enzyme primarily participates in DNA repair processes and is not involved in the elongation of new DNA strands starting at an RNA primer during DNA replication.
D. DNA ligase: This enzyme joins or "ligates" the Okazaki fragments (short DNA segments synthesized on the lagging strand) during DNA replication. It does not elongate the new DNA strand starting at an RNA primer.
E. RNA polymerase: This enzyme is responsible for transcribing DNA into RNA during gene expression and is not involved in DNA replication.
Based on this information, the correct answer is B. DNA polymerase III.