Question

Which one of the following is the sequence on corresponding coding strand, if the sequence on mRNA formed is as follows 5’AUCGAUCGAUCGAUCGAUCGAUCG AUCG 3’?

• A. 3’ UAGCUAGCUAGCUAGCUAGCUAGCUAGC 5’
• B. 5’ ATCGATCGATCGATCGATCGATCGATCG 3’
• C. 3’ ATCGATCGATCGATCGATCGATCGATCG 5
• D. 5’ UAGCUAGCUAGCUAGCUAGCUAGCUAGC 3’

Answer 1

The Correct Option is B

To determine the sequence of the coding strand corresponding to a given mRNA sequence, it's important to remember the relationship between DNA and mRNA transcription. In terms of nucleotide pairing, the DNA coding strand has the same sequence as the mRNA, except that all thymine (T) bases in DNA are replaced with uracil (U) in mRNA. Therefore, if the mRNA sequence provided is:

5' AUCGAUCGAUCGAUCGAUCGAUCGAUCG 3'

The sequence of the corresponding DNA coding strand would be:

5' ATCGATCGATCGATCGATCGATCGATCG 3'

This is because during transcription, RNA polymerase synthesizes mRNA by using the DNA template strand, but the mRNA produced will match the coding strand of DNA except that U is substituted for T. Therefore, the correct answer is the sequence that mimics the coding strand with T replacing U.

Answer 2

The sequence on the mRNA strand is read from the 5' end to the 3' end, and it forms a complementary sequence to the template DNA strand. To find the corresponding coding strand, you need to match the base pairs according to the rules of complementary base pairing:

mRNA: 5' AUCGAUCGAUCGAUCGAUCGAUCGAUCG 3' 
DNA: 3' TAGCTAGCTAGCTAGCTAGCTAGCTAGC 5'

The coding strand is complementary to the template DNA strand. So, the correct sequence on the coding strand is: 
5' ATCGATCGATCGATCGATCGATCGATCG 3'

The correct option is (B): 5’ ATCGATCGATCGATCGATCGATCGATCG 3’