Some are further divided into subtypes. â¢ OCA1, or tyrosinase-related albinism, results from a genetic defect in an enzyme called tyrosinase. This enzyme helps the body to change the amino acid, tyrosine, into pigment. (An amino acid is a âbuilding blockâ of protein.) There are two subtypes of OCA1.
Pyrimidine is group of molecules that are part of the DNA and RNA structure. These molecules feature a single ring structure made of six atoms. There are several pyrimidine molecules, but only cytosine and thymine are part of the DNA structure, while cytosine and uracil are part of the RNA structure. These molecules bind with their purine counterparts to join the two strands of the DNA or RNA polymer.
Cytosine, thymine, and uracil are examples for pyrimidine bases. Adenine and guanine are the two purine bases. DNA has adenine, Guanine, cytosine, and thymine bases, whereas RNA has A, G, C, and uracil (instead of thymine). In DNA and RNA, complimentary bases form hydrogen bonds between them.That is adenine: thiamine/ uracil and guanine: cytosine are complimentary to each other. Pyrimidine has one ring and purine has two rings. â¢ Purine has a pyrimidine ring and an imidazole ring. â¢ Adenine and guanine are the purine derivative present in nucleic acids whereas cytosine, uracil and thymine are the pyrimidine derivatives present in the nucleic acids.