AP BIOLOGY

THE MOLECULAR BASIS OF INHERITANCE

DNA REPLICATION

Question [CLICK ON ANY CHOICE TO KNOW THE RIGHT ANSWER]
Which of the following start the synthesis of a new DNA?
A
RNA primer
B
DNA polymerase III
C
Okazaki fragment
D
DNA ligase
Explanation: 

Detailed explanation-1: -A primer must be synthesized by an enzyme called primase, which is a type of RNA polymerase, before DNA replication can occur.

Detailed explanation-2: -Primase is an enzyme that synthesizes short RNA sequences called primers. These primers serve as a starting point for DNA synthesis. Since primase produces RNA molecules, the enzyme is a type of RNA polymerase.

Detailed explanation-3: -DNA synthesis requires a primer usually made of RNA. A primase synthesizes the ribonucleotide primer ranging from 4 to 12 nucleotides in length. DNA polymerase then incorporates a dNMP onto the 3’ end of the primer initiating leading strand synthesis.

Detailed explanation-4: -Primer synthesis marks the beginning of the actual synthesis of the new DNA molecule. Primers are short stretches of nucleotides (about 10 to 12 bases in length) synthesized by an RNA polymerase enzyme called primase.

Detailed explanation-5: -An RNA primer is a short segment of single-stranded RNA used as a binding site for DNA polymerase to initiate DNA replication. DNA polymerase is only able to add nucleotides to an existing nucleotide chain; it cannot “start from scratch, ” and therefore needs the RNA primer to start the process.

There is 1 question to complete.