Multiple Choice
In the DNA double helix, what type of bonds hold complementary nitrogenous bases together across the two strands?
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7. DNA and Chromosome Structure
DNA Structure
Multiple Choice
In the DNA double helix, what type of chemical bond holds the sugar-phosphate backbone together within a single strand?
A
Hydrogen bonds between complementary nitrogenous bases
B
Van der Waals interactions between stacked bases
C
Ionic bonds between negatively charged phosphate groups and positively charged bases
D
Phosphodiester covalent bonds between the hydroxyl of one sugar and the phosphate of the next nucleotide
Verified step by step guidance1
Understand the structure of a DNA strand: DNA is composed of nucleotides, each containing a sugar, a phosphate group, and a nitrogenous base.
Identify the backbone of the DNA strand: The sugar and phosphate groups form the backbone, which provides structural stability to the strand.
Recognize the type of bond connecting sugars and phosphates: The sugar of one nucleotide is linked to the phosphate group of the next nucleotide through a covalent bond.
Specify the exact bond type: This covalent bond is called a phosphodiester bond, which connects the 3\' hydroxyl group of one sugar to the 5\' phosphate group of the adjacent nucleotide.
Distinguish this from other interactions: Hydrogen bonds occur between complementary bases on opposite strands, while Van der Waals interactions stabilize base stacking; ionic bonds are not involved in backbone formation.
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