Multiple Choice
In terms of overall electrostatic charge at physiological pH, what is the net charge of DNA and what structural feature is primarily responsible for it?
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7. DNA and Chromosome Structure
DNA Structure
Multiple Choice
In the DNA double helix, what interaction primarily holds the two antiparallel strands together?
A
Hydrogen bonds between complementary nitrogenous bases (A–T and G–C)
B
Ionic bonds between the phosphate groups of the two strands
C
Covalent phosphodiester bonds between nucleotides on opposite strands
D
Peptide bonds between deoxyribose sugars on opposing strands
Verified step by step guidance1
Step 1: Understand the structure of the DNA double helix, which consists of two antiparallel strands made up of nucleotides.
Step 2: Recognize that each nucleotide contains a sugar, a phosphate group, and a nitrogenous base (A, T, G, or C).
Step 3: Identify the types of bonds present: phosphodiester bonds link nucleotides within the same strand, while hydrogen bonds form between complementary nitrogenous bases on opposite strands.
Step 4: Recall that hydrogen bonds specifically occur between adenine (A) and thymine (T) with two hydrogen bonds, and between guanine (G) and cytosine (C) with three hydrogen bonds, stabilizing the double helix.
Step 5: Conclude that the primary interaction holding the two antiparallel strands together is the hydrogen bonding between complementary nitrogenous bases, not ionic, covalent phosphodiester, or peptide bonds.
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