Question

which answer choice below correctly describes the structure of dna? (1 point)
sugar - phosphate backbone with nitrogen bases coming off a single helix.
sugar - nitrogen base backbone with phosphates in the middle forming a double helix.
a 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.

Explanation:

DNA has a double - helix structure. The sugar - phosphate groups form the backbone on the outside, and the nitrogen bases are in the middle, forming base - pairs that hold the two strands of the double - helix together.

Answer:

A sugar - phosphate backbone with nitrogen bases in the middle forming a double helix.