Question

1. Active mitosis promoting factor (MPF) triggers events that include (read carefully)

		DNA synthesis
		degradation of cyclin
		breakdown of the spindle apparatus
		formation of the nuclear envelope

2. P87 is a proto-oncogene. What is the function of P87; and what is the effect of a mutation in the gene for P86 that decreases the efficiency of the P86 protein?

		move a cell past at a check point in cell cycle; decreased chance of cancer
		halt a cell at a check point in cell cycle; increased chance of cancer
		move a cell past at a check point in cell cycle; increased chance of cancer
		halt a cell at a check point in cell cycle; decreased chance of cancer

Answer 1

1. MPF Triggers breakdown of nuclear membrane and formation of spindle. DNA synthesis is completed in S phase. A systematic degradation of cyclins is essential for cell cycle progression.

MPF thus triggers degradation of cyclins.

2. Normally poto oncogene move the cell through the cell cycle and increase chances of cancer.

As defective protein resulted by the mutation in proto oncogene will result into halting the cell cycle at a particular point and decrease chances of cancer.