Answer:
B. nitrogenous bases
Explanation:
Nitrogenous bases are chemical compounds formed by slightly alkaline rings that contain nitrogen. Together with sugar and a phosphoric acid, they make up ribonucleic acid (RNA) and deoxyribonucleic acid (DNA). It is through these nitrogenous bases that the two strands of DNA are linked. This is exactly what we can see in the picture.
There are five types of bases, which are classified into two groups:
- Purine or purine nitrogenous bases: adenine (A) and guanine (G);
- Pyrimidine or pyrimidine nitrogenous bases: cytosine (C), thymine (T) and uracil (U).
Pyrimidine bases are derived from pyrimidine and are formed by a ring (hexagonal) of carbon and nitrogen. The purine bases are derived from purine, are larger and have two rings (one hexagonal and one pentagonal) of carbon and nitrogen.
