Multiple Choice
In the structure of DNA, which component is primarily responsible for the molecule's overall negative charge at physiological pH?
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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
Ionic bonds between the phosphate groups of the two strands
B
Covalent phosphodiester bonds between nucleotides on opposite strands
C
Peptide bonds between the deoxyribose sugars of the two strands
D
Hydrogen bonds between complementary nitrogenous bases (A–T and G–C)
Verified step by step guidance1
Understand the structure of DNA: DNA consists of two strands running in opposite directions (antiparallel), forming a double helix.
Identify the backbone of each strand: Each strand has a sugar-phosphate backbone connected by covalent phosphodiester bonds between nucleotides on the same strand.
Recognize that the two strands are held together not by covalent bonds but by weaker interactions to allow strand separation during replication and transcription.
Focus on the nitrogenous bases (adenine, thymine, guanine, cytosine) that extend from each sugar in the backbone and pair specifically (A with T, G with C).
Know that hydrogen bonds form between these complementary nitrogenous bases, stabilizing the double helix by holding the two antiparallel strands together.
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