In the DNA double helix, which components form the sugar-phosphate backbone of each strand?

• A. Nitrogenous bases connected to each other by phosphodiester bonds
• B. Alternating deoxyribose sugars and phosphate groups linked by phosphodiester bonds
• C. Alternating ribose sugars and phosphate groups linked by peptide bonds
• D. Amino acids linked together by glycosidic bonds

Answer: (B)

Verified step by step guidance

1. Recall the structure of the DNA double helix, which consists of two strands running in opposite directions.
2. Identify the main components of each DNA strand: a sugar, a phosphate group, and nitrogenous bases.
3. Understand that the sugar in DNA is deoxyribose, a five-carbon sugar, which alternates with phosphate groups to form the backbone.
4. Recognize that these sugar and phosphate groups are connected by phosphodiester bonds, which link the 3' carbon of one sugar to the 5' carbon of the next sugar.
5. Note that the nitrogenous bases are attached to the sugar molecules and pair with complementary bases on the opposite strand, but they do not form the backbone.