Question

Which of the following correctly describes the linkage that will be formed with the nitrogen base shown in the image below while building a strand of RNA?
A) Two hydrogen bonds will form with uracil.
B) Two glycosidic bonds will form with adenine.
C) Three hydrogen bonds will form with guanine.
D) Three glycosidic bonds will form with thymine.

Answer 1

Answer:

C) Three hydrogen bonds will form with guanine.

Explanation:

Generally the DNA molecule is made up of Purines  bases of Adenine and Guanine,and Pyrimidine of Cytosine and Guanine.However,RNA contains a different pyrimidine of Uracil.Thus the pairing is A-U  am C-G.The uracil replaces Thymine.

The structure above is a Pyrimidine,because it is made up of single ring structure(an heterocylclic  aromatic  structure) compare to double structure of purines. Heterocyclic means it is ring form.Aromatic means it has resonance bonds which shift with the rings for stability.

It is also contains of two substitutes at position 4 of the ring structure (amineNH2) and at 2 which is the Keto group(=0).Therefore the structure is Cytosine.

In RNA structure the Cytosine pair with the three hydrogen bonds with guanine,while Adenine pair with Uracil.This ensures stability of the RNA structure.