Question

if one strand of a dna molecule has the sequence g - a - t - t - a - c - a, what is the sequence of the complementary strand?
c - a - t - t - a - g - a
g - a - t - t - a - c - a
c - u - a - a - u - g - u
c - t - a - a - t - g - t

Explanation:

In DNA, base - pairing rules are: G (guanine) pairs with C (cytosine), A (adenine) pairs with T (thymine).
For the given strand G - A - T - T - A - C - A:

• G pairs with C
• A pairs with T
• T pairs with A
• T pairs with A
• A pairs with T
• C pairs with G
• A pairs with T

Answer:

C - T - A - A - T - G - T