CCB Exam 2 Practice Questions and Correct Answers

Why is cyclin D frequently amplified or over-expressed in human cancers? know that cyclin D is the initiator of the G1 phase of cell cycle and works as the other kinase complexes fluctuates. over expression of cyclin D in turn leads to increased cell division and growth Which part of the cell cycle usually takes the longest amount of time? What is happening in the cell at this time? G1 phase usually takes the most amount of time because it is then that the cell cycle clock is taking in signals from outside and inside the cell to determine progression past R Restriction point or pausing into quiescent phase of G0 Name the cyclin-cdk complexes that form at different cell cycle phases. What happens to the levels of the cyclins as the cell cycle progresses? CDK4/6|CyclinD then CDK2|CyclinE then CDK2|CyclinA CDC2|CyclinA then CDC2|CyclinB When Rb gets hyper-phosphorylated by cyclin E-CDK2 during the cell cycle, what is the result? When pRb gets hyper-phosphorylated by CyclinE|CDK2 after being hypo-phosphorylated by Cyclin4/6|CDK2, it released E2F so that it may bind to transcribe remember that pRb has corepressor pocket proteins but it is is the main one then you have HDAC that deacetylates disallowing proper configuration for RNA polymerase to to transcribe until replaced by HAP who is an acetyltransferase that allows the RNA polymerase to its job What is the difference between a quiescent cell and a senescent cell? quiescent cell is just one who is quiet or paused in G0 but has the capacity to undergo cell cycle senescent cells are unable to undergo cell cycle, essentially in a phase of being without being *not dead* but at a dead end In which period of the cell cycle are cells responsive to mitogenic growth factors and TGF-β? during G1 phase where the cell cycle clock is intaking all signals to determine progression or quiescence, once at R point, no longer getting any influence from growth factors and TGF beta Suppose you were given a section of human tissue that contained both tumor and normal tissue. What experiment could you perform to determine whether the fraction of cells passing the R-point in tumors was higher than normal tissue? immunochemistry or stain to determine inhibitor proteins that would haunt progression, no inhibitor proteins then probably cancerous with higher levels of cells passing R point into progression than in normal tissue