Question

3'-AAATGCGCCATA-5’ is the sequence of nucleotides on a gene. After transcription the sequence of nucleotides in the mRNA formed from it and the sequence of nucleotides in the corresponding coding strand of DNA will be

• A. 5'-UAU-GUT-CCA-UUU-3' and 5'AUA-CAU-GGU-AAA-3'
• B. 5'-UUU-ACG-CGG-UAU-3' and 5'TTT-ACG-CGG-TAT-3'
• C. 5'-UAU-CGC-GCA-UUU-3' and 5'AUA-GCG-CGU-AAA-3'
• D. 5'-UUU-ACC-TUG-UAU-3' and 5'AAA-UGG-UAC-AUA-3'

Answer 1

The correct option is B 5'-UUU-ACG-CGG-UAU-3' and 5'TTT-ACG-CGG-TAT-3'

If the sequence of nucleotides on a gene is 3'-AAA TGC GCC ATA-5', the transcribed mRNA sequence will be
5'-UUU ACG CGG UAU-3' and the sequence of nucleotides in the corresponding coding strand of DNA will be 5'-TTT ACG CGG TAT-3’.


3’→ 5’ strand of DNA acts as a template strand; because transcription takes place in the 5'→ 3’direction.
The transcribed mRNA and template strand would have complementary base pairs, where adenine of DNA pairs with uracil, thymine with adenine, cytosine with guanine and guanine with cytosine in RNA.

The diagram below can be referred for more clarity:


Coding strand is a 5’ ⇾ 3’ strand of DNA. It is called coding strand because it’s nitrogenous base sequences are the same as the transcribed RNA, except for uracil. In place of the uracil of RNA, the coding strand of DNA has thymine.

The diagram below can be referred for more clarity: