Question

A segment of DNA has the sequence 5'-ATGCCC-3'. The complementary sequence would be

A. 5'-GGGCAT-3'
B. 5'-CCCGTA-3'
C. 5'-TACGGG-3'
D. 5'-ATGGGG-3'

Answer 1

The correct complementary sequence to the given DNA segment 5'-ATGCCC-3' is 5'-GGGCAT-3', which follows DNA base pairing rules with antiparallel strand orientation.

Step-by-step explanation:

When given a DNA sequence, such as 5'-ATGCCC-3', the complementary sequence is formed by pairing the nucleotide bases with their complements: adenine (A) with thymine (T) and cytosine (C) with guanine (G). The two strands of DNA are antiparallel, meaning that the 5'-end of one strand pairs with the 3'-end of the other strand. Therefore, the complementary sequence to 5'-ATGCCC-3' would be 3'-TACGGG-5', which when written in the conventional 5'-to-3' direction, becomes 5'-GGGCAT-3'. Answer A, 5'-GGGCAT-3', is the correct complementary sequence.