Question

What is the need for a primer in transcription? Group of answer choices It ensures the fidelity of the newly synthesized RNA strand. RNA polymerases requires a preexisting strand with a nucleotide having a 3'−OH. RNA polymerase requires a preexisting strand with a nucleotide having a 5'−OH. There is none.

Answer 1

In transcription, a primer is not needed because RNA polymerase can initiate RNA synthesis without a preexisting strand. DNA replication, on the other hand, requires a short RNA primer synthesized by primase to start the synthesis of DNA.

Step-by-step explanation:

The need for a primer in DNA replication is essential because DNA polymerases require a preexisting strand with a nucleotide having a free 3'-OH group to initiate synthesis. However, in the process of transcription, RNA polymerase does not need a primer. During transcription, RNA polymerase can synthesize a new RNA strand from scratch, using the DNA template and ribonucleotide 5' triphosphates (ATP, UTP, CTP, GTP). In contrast, during DNA replication, an enzyme called primase synthesizes a short RNA segment known as a primer, which provides the necessary free 3'-OH group for the DNA polymerase to start adding DNA nucleotides.

Answer 2

There is none.

Step-by-step explanation:

DNA polimerase needs a preexisting 3'−OH to start building a DNA strain, and that´s why in DNA replication a primer made of RNA is needed to start the process.

RNA polimerase does not need a 3'−OH to start building a RNA strain. It attaches and moves along the DNA adding ribonucleotides in the growing RNA chain.