Multiple Choice
Which types of chemical bonds are primarily responsible for holding the two strands of DNA together in the double helix?
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7. DNA and Chromosome Structure
DNA Structure
Multiple Choice
In the DNA double helix, what are the “sides” (backbone) of the DNA ladder primarily made of?
A
A polypeptide chain of amino acids linked by peptide bonds
B
A continuous chain of hydrogen bonds between complementary bases
C
Alternating deoxyribose sugars and phosphate groups
D
Alternating nitrogenous bases (A, T, G, C) linked by phosphodiester bonds
Verified step by step guidance1
Recall the structure of the DNA double helix, which resembles a twisted ladder with two main components: the "rungs" and the "sides" (or backbone).
Identify that the "rungs" of the ladder are formed by pairs of nitrogenous bases (adenine, thymine, guanine, and cytosine) connected by hydrogen bonds.
Understand that the "sides" or backbone of the DNA ladder are made up of repeating units that provide structural support and stability to the molecule.
Recognize that these repeating units consist of alternating sugar and phosphate groups, specifically deoxyribose sugars linked to phosphate groups via phosphodiester bonds.
Conclude that the backbone is not made of amino acids or continuous hydrogen bonds, but rather an alternating chain of deoxyribose sugars and phosphate groups.
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