Question

In which order are the following enzymatic activities required for DNA replication on the lagging strand in eukaryotes? Each activity may be used more than once or not at all.

1) DNA polymerase
2) RNA polymerase
3) DNase
4) RNase
5) DNA ligase
A) 2 1 4 1 5
B) 1 2 3 4 5
C) 5 2 1 3 4
D) 3 2 1 4 3
E) 2 1 3 1 5

Answer 1

The correct order of enzymatic activities for DNA replication on the lagging strand in eukaryotes is primase (RNA polymerase), DNA polymerase, RNase (for RNA primer removal), DNA polymerase (for Okazaki fragment synthesis), and DNA ligase, which corresponds to option A: 2 1 4 1 5.

Step-by-step explanation:

The process of DNA replication on the lagging strand in eukaryotes involves several enzymatic activities that occur in a specific order. First, primase (functionally similar to RNA polymerase) synthesizes RNA primers complementary to the DNA strand (option 2). Once the RNA primers are in place, DNA polymerase begins adding nucleotides to extend the DNA from the primer (option 1). As the DNA polymerase synthesizes discontinuous segments known as Okazaki fragments, RNA primers are removed and replaced with DNA nucleotides, a task that includes the action of flap endonuclease (which can be thought of as a function similar to DNase or RNAase for the RNA primer removal part) (option 3 or 4, respectively). Lastly, DNA ligase seals the gaps between the Okazaki fragments, completing the synthesis of the lagging strand (option 5).

Therefore, the correct order of enzymatic activities for the replication on the lagging strand of eukaryotic DNA would be option A: 2 1 4 1 5.