Question

On which strand of DNA, mRNA is constructed?
a. Sense strand
b. Antisense strand
c. Both the strand
d. Anyone strand

Answer 1

Hint: The process of conversion of mRNA to DNA is called transcription. It is the first step to gene expression. The process involves copying the DNA sequence of a gene to make an RNA molecule out of it. The enzyme involved in this process is RNA polymerase, which links the two nucleotides to form a strand of RNA.

Complete answer:
• In eukaryotic cells, there are several types of RNA polymerase that make various types of RNA, but in prokaryotes, there is only one type of RNA polymerase that transcripts all the required RNA molecules.
• The process of initiation is the first step of RNA formation. The RNA polymerase enzyme along with other factors binds to the DNA strand and transcription takes place. This position where all the factors bind is known as the promoter region.
• After all the components are in place, DNA transcription takes place. RNA polymerase moves on the DNA’s template strand by $3^{\prime }\to 5^{\prime }$ adding together the complementary nucleotides. The complementary base pairing creates a new mRNA strand that is complementary to the template or the sense strand of DNA.
• The mRNA peels off from the sense strand and grows. This separation and editing are required for the mRNA to perform the desired function.
• The process of clipping out the non-coding nucleotide sequences is known as editing. Also, adenine nucleotides that are called poly-A are added to the $3^{\prime }$ end of the mRNA.

Hence, the correct answer is option (A).

Option (B), (C), and (D) is not correct because the antisense strand is not used in transcription, rather the new mRNA formed is itself the anti-sense of DNA.

Note: After the transcription process of mRNA is over, translation occurs and the information which the mRNA molecule is supposed to convey is directed for the creation of a protein molecule. The ribosomes synthesize the required proteins for the message to be conveyed and the action to take place and the purpose is fulfilled.