Final answer:
Nitrogenous bases that can undergo deamination include adenine and guanine. Deamination involves the hydrolytic removal of amino groups from these bases. DNA repair systems can recognize and correct the resulting unnatural bases.
Step-by-step explanation:
Nitrogenous bases that can undergo deamination include adenine and guanine. Deamination is the hydrolytic removal of amino groups from these bases. When deamination occurs, the amino groups are converted into ammonia or ammonium ion (NH4+) and the bases are transformed into hypoxanthine and xanthine respectively. These unnatural bases are recognized and corrected by DNA repair systems, but occasionally the U-A base pair remains un-repaired.