Question

E. coli DNA pol I (full length)

In vivo function:
Filling in short stretches of single-stranded DNA that arise from:

a. DNA ____ (lagging strand).

b. DNA ____ when damaged bases have been removed.

Answer 1

E. coli DNA pol I fills the gaps in the lagging strand after the removal of RNA primers and also repairs DNA by filling in after damaged bases are removed.

Step-by-step explanation:

The in vivo function of full-length DNA polymerase I (DNA pol I) in Escherichia coli (E. coli) is to fill in short stretches of single-stranded DNA that arise from specific processes during DNA replication. For the first scenario, a. DNA replication, DNA pol I fills in the gaps on the lagging strand after the RNA primers used for Okazaki fragment synthesis have been removed. For the second scenario, b. DNA repair, when damaged bases have been excised, DNA pol I fills in the resulting gaps with new DNA.

During the replication of the lagging strand, DNA is synthesized in short stretches known as Okazaki fragments, each beginning with an RNA primer. DNA pol I possesses exonuclease activity, which removes these RNA primers and replaces them with DNA nucleotides. The enzyme DNA ligase then seals these gaps, forming a continuous DNA strand. In DNA repair, when nucleotide excision repair excises damaged bases, DNA pol I fills the space by synthesizing DNA using the available template strand.