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Multiple Choice
Which of the following statements is true about double-stranded DNA?
A
The two strands are complementary and antiparallel.
B
The two strands are identical in sequence.
C
The two strands are held together by covalent bonds.
D
The two strands run in parallel directions.
Verified step by step guidance
1
Understand the structure of double-stranded DNA: DNA is composed of two strands that form a double helix.
Recognize that the two strands of DNA are complementary: This means that the sequence of bases on one strand determines the sequence on the other strand. Adenine (A) pairs with Thymine (T), and Cytosine (C) pairs with Guanine (G).
Identify that the strands are antiparallel: This means that one strand runs in the 5' to 3' direction, while the other runs in the 3' to 5' direction.
Clarify that the strands are held together by hydrogen bonds, not covalent bonds: Hydrogen bonds form between the complementary bases (A-T and C-G) to stabilize the double helix structure.
Conclude that the correct statement is: 'The two strands are complementary and antiparallel.' This reflects the true nature of DNA's structure.