Cytosine thymine guanine and adenine are the nitrogenous bases found in the nucleotides that form DNA.DNA is made up of 3 parts:(1)Phosphate group(2)Deoxyribose(3)Nitrogen containing base.Complimentary pairing/ bonding through weak hydrogen bonds occurs between Cytosine and Guanine(first pair) and Adenine and Thymine. Are the four bases in DNA. They make the base pairs of adenine->thymine Guanin -> cytosine and visa/versa. In RNA thymine is replaced with uracil