Question

Select the phrases that accurately describe properties of the most common form of the DNA double helix. a. The phosphodiester bonds between nucleotide residues run in opposite directions in the two strands. b. The sugar–phosphate backbone is exposed to the solvent, whereas the nitrogenous bases are in the interior of the double helix. c. Base pairs have a spacing of . d. A helical turn consists of about . e. DNA contains equal amounts of adenine and guanine (the purines) and equal amounts of cytosine and thymine (the pyrimidines).

Answer 1

The sugar and phosphate bond is placed outward of the DNA towards the solvent and the base of nitrogen is inside the helix.

Explanation:

The edges that are outward to the double helix formation of DNA are composed by sugar and phosphate molecules and make the backbone.

These two strands of DNA is placed in the opposite direction from the helix. But the nitrogen base is there inside the helix. It shapes like a ladder rung because of the hydrogen bond. This bond keeps the backbone held together.