Q28-10P - Organic Chemistry (Mcmurry)

Question

What is the base sequence in the original DNA strand on which the mRNA sequence in problem 28-9 was made?

CUU-AUG-GCU-UGG-CCC-UAA

Step-by-Step Solution

Answer

The base sequence in the original DNA strand can be written as 

$(3\text{'})-\mathrm{GAA}-\mathrm{TAC}-\mathrm{CGA}-\mathrm{ACC}-\mathrm{GGG}-\mathrm{ATT}-(5\text{'})$

Step 1: Given mRNA sequence

The mRNA sequence can be given as,

CUU-AUG-GCU-UGG-CCC-UAA

Step 2: Formation of sense and antisense DNA strand

The original DNA strand on which the formation of mRNA is none other than antisense DNA. The complement of antisense DNA which is formed by the replacement of A by U, T by A, C by G, and G by C is mRNA. The antisense DNA strand will be its complement.

$\mathbf{(}\mathbf{3}\mathbf{\text{'}}\mathbf{)}\mathbf{-}\mathbf{GAA}\mathbf{-}\mathbf{TAC}\mathbf{-}\mathbf{CGA}\mathbf{-}\mathbf{ACC}\mathbf{-}\mathbf{GGG}\mathbf{-}\mathbf{ATT}\mathbf{-}\mathbf{(}\mathbf{5}\mathbf{\text{'}}\mathbf{)}$