Question

In addition to synthesizing DNA, DNA polymerase I also has a second catalytic activity—it can __________.

a) synthesize short RNA sequence
b) synthesize short peptide sequences
c) remove RNA primers
d) ligate short segments of DNA together

Answer 1

DNA polymerase I removes RNA primers, while DNA ligase seals DNA segments together.

Step-by-step explanation:

DNA polymerase I has a second catalytic activity: it can remove RNA primers from the developing copy of DNA. This is an important step in DNA replication because RNA primers are needed to initiate DNA synthesis, but they must be removed and replaced with DNA nucleotides. This activity of DNA polymerase I is also involved in DNA repair. DNA ligase, on the other hand, seals the ends of the new DNA segment, particularly the Okazaki fragments in the lagging strand. It joins separate DNA fragments together by catalyzing the formation of phosphodiester bonds between them.