AS.020.305 Midterm: cell bio final study sheet (dragged) 10
Document Summary
Points, the cycle stops if damaged dna is detected. Dna damage can block entry from g1into s phase, it can slow s phase once it has begun, and it can block the transition from s phase to m phase. These delays facilitate dna repair by providing the time needed for the repair to reach completion. Some of the subunits are distinct proteases whose active sites face the cylinder"s inner chamber. Ubiquitin exists in cells either free or covalently linked to many different intracellular proteins. For many proteins, tagging by ubiquitin results in their destruction by the proteasome. However, in other cases, ubiquitin tagging has an entirely different meaning. Ultimately, it is the number of ubiquitin molecules added and the way in which they are linked together that determines how the cell interprets the ubiquitin message.
