객관식
In the context of DNA structure, what type of biomolecule are DNA and RNA?
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7. DNA and Chromosome Structure
DNA Structure
객관식
In terms of overall electrical charge at physiological pH, what net charge does DNA typically carry and what structural feature is primarily responsible?
A
Net positive charge due to the amino groups on the nitrogenous bases
B
Net neutral charge because base pairing cancels the charges in the helix
C
Net positive charge due to hydrogen bonding between complementary bases
D
Net negative charge due to the phosphate groups in the sugar-phosphate backbone
검증된 단계별 안내1
Understand that DNA is composed of nucleotides, each containing a sugar, a phosphate group, and a nitrogenous base.
Recognize that at physiological pH (around 7.4), the phosphate groups in the sugar-phosphate backbone lose protons, becoming negatively charged.
Note that the nitrogenous bases do not contribute a net positive charge because their amino groups are not ionized to carry a positive charge at physiological pH.
Realize that base pairing (hydrogen bonding) does not neutralize the overall charge; it only stabilizes the double helix structure.
Conclude that the net charge of DNA is negative due to the presence of negatively charged phosphate groups along the backbone.
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