Question

In DNA replication the primer is?
(a) A small deoxyribonucleotide polymer
(b) A small ribonucleotide polymer
(c) Helix destabilizing protein
(d) Enzyme taking part in joining the nucleotides of new strained

Answer 1

The polymer or a protein required by the DNA polymerase to bind to the template before it forms a complementary strand in the DNA replication.

Complete answer:
In the replication process of DNA, initiation of DNA synthesis occurs at a site called the origin of replication (ori). For the synthesis of a new DNA, a short fragment of ribonucleic acid is required. This short fragment of RNA is called a primer.

Additional Information: Origin of replication(ori) site in the DNA replication process is the site where replication is initiated
- In prokaryotes, only one ori site is present whereas in eukaryotes multiple ori sites are present.
- DNA is a specific protein that binds to ori site for replication resulting in dsDNA to separate
- Two complementary strands of DNA separate at the site of replication to form a bubble called replication bubble. In eukaryotes, multiple replication bubbles are formed which is essential for the rapid replication process
- A short fragment of RNA is required for the synthesis of new DNA is called primer.
- The enzyme primase in association with single-stranded binding proteins forms a complex called primosome and produces an RNA primer.
- A constant synthesis and supply of RNA primers should occur on lagging strand of DNA
So, the correct answer is 'a small ribonucleotide polymer'.

Note: In the lagging strand of DNA, enzyme primase forms a complex with DNA polymerase which initiates the synthesis of Okazaki fragments
RNA primers are used in diagnostic techniques like DNA sequencing and polymerase chain reaction(PCR).