Question

Consider the following DNA template strand:

3’            ATC        CAG       ATG        AAC        AGC     AAT        5’
Which is the correct complementary mRNA strand?

A. 5' UAG GUC UAC UUG UCG UUA 3'
B. 5' ATC CAG ATG AAC AGC AAT 3'
C. 3' UAG UCG UAC UUG GUC UUA 5'
D. 3' TAG GTC TAC TTG TCG TTA 5'

Answer 1

The correct mRNA strand complementary to the DNA template strand 3' ATC CAG ATG AAC AGC AAT 5' is 5' UAG GUC UAC UUG UCG UUA 3', which is option A in the choices provided.

Step-by-step explanation:

The correct complement to the DNA template strand 3' ATC CAG ATG AAC AGC AAT 5' is the mRNA strand that is formed during transcription. During this process, the enzyme RNA polymerase reads the template DNA strand and synthesizes an mRNA strand by pairing the complementary bases but with uracil (U) in place of thymine (T). Hence, adenine (A) pairs with uracil (U), cytosine (C) pairs with guanine (G), and guanine (G) pairs with cytosine (C).

Therefore, the complementary mRNA strand will be: 5' UAG GUC UAC UUG UCG UUA 3', which corresponds to option A. This sequence is complementary and antiparallel to the given DNA template strand, matching each base with its RNA complement. It is important to ensure we read the DNA template strand in the 3' to 5' direction to get the correct 5' to 3' mRNA sequence.