Final answer:
Uracil glycosylase leaves behind an apyrimidinic (AP) site, a sugar without a base, which is then processed through DNA repair mechanisms to restore the correct DNA sequence.
Step-by-step explanation:
When uracil glycosylase cleaves the bond in DNA, it leaves behind an apyrimidinic (AP) site, which is essentially a deoxyribose sugar without the attached base uracil. This enzyme is a part of the DNA base excision repair pathway, which identifies and corrects damaged or incorrect bases in the DNA sequence. The removal of uracil by uracil glycosylase is critical to prevent mutations since uracil is not typically present in DNA and can arise through the spontaneous deamination of cytosine. After the base uracil is removed, the AP site is recognized by AP endonuclease, which then makes a nick in the DNA strand. This is followed by further steps carried out by phosphodiesterase, DNA polymerase, and DNA ligase to complete the repair process and restore the DNA molecule to its correct sequence.