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Question 525
Biochemistry → General
Classification
Question
SSBAQuestion Header
A DNA strand has the sequence 3′-AGGTCGCG-5′. Which sequence represents its complementary antiparallel strand?
Question Stem
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Options
A
5′-TCCAGCGC-3′
B
5′-AGGTCGCG-3′
C
3′-TCCAGCGC-5′
D
5′-UCCAGCGC-3′
E
3′-AGGTCGCG-5′
Explanation
DNA consists of two antiparallel complementary strands. Adenine pairs with thymine and cytosine pairs with guanine. Therefore, the strand complementary to 3′-AGGTCGCG-5′ is 5′-TCCAGCGC-3′.
Option Validity
B) This repeats the original base sequence rather than applying complementary base pairing.
C) The bases are complementary, but the strand orientation is not antiparallel to the sequence given.
D) Uracil is not one of the bases listed for DNA; thymine pairs with adenine.
E) This reproduces the original strand rather than its complementary antiparallel strand.
Further Reading
Richa Saxena. Textbook for MRCOG-1: Basic Sciences in Obstetrics & Gynaecology. Biochemistry and Nutrition — Biochemistry — DNA. Printed page 128.