Multiple Choice
In the DNA double helix, what primarily holds the two antiparallel strands together?
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7. DNA and Chromosome Structure
DNA Structure
Multiple Choice
In the DNA double helix, what holds the two antiparallel strands together?
A
Covalent phosphodiester bonds between bases on opposite strands
B
Peptide bonds linking nucleotides across the helix
C
Disulfide bonds between deoxyribose sugars on opposite strands
D
Hydrogen bonds between complementary base pairs (A–T and G–C)
Verified step by step guidance1
Understand the structure of DNA: DNA is composed of two antiparallel strands forming a double helix.
Recall the types of bonds in DNA: Covalent phosphodiester bonds link nucleotides within the same strand, forming the sugar-phosphate backbone.
Identify the bonds between strands: The two strands are held together by hydrogen bonds between complementary nitrogenous bases (adenine pairs with thymine, guanine pairs with cytosine).
Recognize that peptide bonds link amino acids in proteins, not nucleotides in DNA, so they do not hold DNA strands together.
Note that disulfide bonds occur between cysteine residues in proteins, not between sugars in DNA, so they are not involved in holding DNA strands together.
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