Which nucleotides are used to synthesize the primer?

Which nucleotides are used to synthesize the primer?

• A. RNA nucleotides
• B. DNA nucleotides
• C. Deoxyribonucleotides
• D. Amino acids

Answer: (A)

Synthesis of the primer is done by primase using RNA nucleotides. The RNA nucleotides (A, G, C, U) serve as substrates to build a short RNA primer because DNA polymerases cannot start a new strand on a bare template—they need a 3' hydroxyl group to extend. The RNA primer provides that starting point and can be laid down de novo. Afterward, DNA polymerases take over and replace the RNA primer with DNA nucleotides (deoxyribonucleotides) to continue synthesis. Amino acids aren’t used in forming the primer.

Synthesis of the primer is done by primase using RNA nucleotides. The RNA nucleotides (A, G, C, U) serve as substrates to build a short RNA primer because DNA polymerases cannot start a new strand on a bare template—they need a 3' hydroxyl group to extend. The RNA primer provides that starting point and can be laid down de novo. Afterward, DNA polymerases take over and replace the RNA primer with DNA nucleotides (deoxyribonucleotides) to continue synthesis. Amino acids aren’t used in forming the primer.