Question

Which one of the following is the complementary sequence for the DNA with 5’-CGTACTA-3'.
a. 5'-TAGTACG-3
b. 5'-ATCATGA-3
c. 5-UTCUTGC-3'
d. 3'-GCATGAT-5

Answer 1

Hint: During DNA transcription, the DNA template strand was read by the enzyme RNA polymerase from the 3’ to 5’ direction, but the formation of mRNA is in 5’ to 3’, where the mRNA is single-stranded and again it undergoes translation.

Complete answer:
- DNA and RNA are nothing but a sequence of nucleotide base pairs, arranged in a certain model
- Nucleotides are the building blocks of the nucleic acids and they consist of a sugar molecule and phosphate and nitrogen base
- The nucleotides present in both DNA and RNA are adenine(A), guanine(G), Thymine( T), Cytosine (C)
- Whereas in the RNA, the Thiamine is replaced by the uracil (U).
- During transcription, The DNA molecule is copied at a certain sequence to produce the mRNA.
- It is initiated by the enzyme, RNA polymerase where it reads the sequence of DNA from 3’ to 5’ end direction
- RNA polymerase is attached to the promoter site and the transcription bubble begins in the strand.
- The double-stranded is broken by breaking the hydrogen bonds, which hold the two strands of DNA together.
- The above-given question they asked about the DNA sequence of the complementary strand, which means the DNA sequence of the opposite strand, as we know in DNA cytosine bonds with guanine, and adenine with thymine.
- The sequence is 5’ CGTACTA 3’, now the complementary sequence from 3’ GCATGAT 5’

Hence, the correct answer is option (D).

Note: During transcription, DNA has a template and nontemplate strand, where the mRNA is formed by complementary bases on the template strand, and it is nothing but looks like a sequence in the Non-template strand.