Which answer choice below correctly describes the structure of DNA?
Sugar phosphate backbone with nitrogen bases coming off a single helix.
Sugar nitrogen base backbone with phosphates in the middle forming a double helix.
Sugar phosphate backbone with nitrogen bases in the middle forming a double helix.
Nitrogen bases on the outside with sugar phosphate in the middle of a double helix.
Sugar phosphate backbone with nitrogen bases in the middle forming a double helix.
The correct answer choice that describes the structure of DNA is:
Sugar phosphate backbone with nitrogen bases in the middle forming a double helix.
To understand why this answer choice is correct, let's break it down:
1. Sugar phosphate backbone: The backbone of DNA is made up of alternating sugar and phosphate molecules. The sugar in DNA is called deoxyribose, and the phosphate group is responsible for linking the sugars together.
2. Nitrogen bases in the middle: Inside the sugar-phosphate backbone, there are nitrogenous bases. These nitrogenous bases include adenine (A), thymine (T), cytosine (C), and guanine (G). The bases pair up, with adenine always binding with thymine and cytosine always binding with guanine, through hydrogen bonds.
3. Forming a double helix: The structure of DNA is a double helix, which means it has two spiral strands that are wound around each other. The strands are anti-parallel, meaning they run in opposite directions, and the nitrogen bases from each strand interact with each other through hydrogen bonding.
Therefore, the correct choice is "Sugar phosphate backbone with nitrogen bases in the middle forming a double helix."