Multiple Choice
In the context of DNA structure, which nitrogenous base is not found in DNA?
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7. DNA and Chromosome Structure
DNA Structure
Multiple Choice
In the DNA double helix, which type of bond primarily holds the two strands together across the helix (between complementary bases)?
A
Phosphodiester covalent bonds between nucleotides in opposite strands
B
Glycosidic bonds between the sugar and phosphate groups of opposite strands
C
Peptide bonds between nitrogenous bases
D
Hydrogen bonds between complementary base pairs
Verified step by step guidance1
Understand the structure of the DNA double helix: it consists of two strands made up of nucleotides, each containing a sugar, phosphate group, and nitrogenous base.
Recognize that the backbone of each strand is held together by phosphodiester covalent bonds between the sugar of one nucleotide and the phosphate of the next nucleotide within the same strand.
Identify that the two strands are held together across the helix by interactions between the nitrogenous bases of opposite strands, not by bonds involving the sugar or phosphate groups.
Recall that the specific interaction between complementary bases (adenine with thymine, and guanine with cytosine) is through hydrogen bonds, which are weaker than covalent bonds but allow the strands to separate during processes like replication.
Conclude that the primary bonds holding the two strands together across the helix are hydrogen bonds between complementary base pairs.
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