Define and indicate the significance of (a) Okazaki fragments, (b) DNA ligase, and (c) primer RNA during DNA replication.

Key Concepts

Okazaki Fragments

Okazaki fragments are short sequences of DNA nucleotides synthesized on the lagging strand during DNA replication. They are formed because DNA polymerase can only add nucleotides in a 5' to 3' direction, necessitating the synthesis of these fragments in a discontinuous manner. Each fragment is later joined together to create a continuous strand, highlighting their crucial role in ensuring accurate DNA replication.

DNA Ligase

DNA ligase is an essential enzyme that facilitates the joining of Okazaki fragments by forming phosphodiester bonds between adjacent nucleotides. This enzyme plays a critical role in sealing nicks in the DNA backbone, ensuring the integrity and continuity of the newly synthesized DNA strand. Without DNA ligase, the replication process would result in incomplete and fragmented DNA.

Primer RNA

Primer RNA, or RNA primers, are short strands of RNA synthesized by the enzyme primase that provide a starting point for DNA polymerase during DNA replication. These primers are necessary because DNA polymerase cannot initiate synthesis on its own; it requires a free 3' hydroxyl group to add nucleotides. The presence of primer RNA is vital for the initiation of both leading and lagging strand synthesis.