Question

QUESTION 7 If you inject a G1 cell that contains 36 chromosomes with a G2/M cyclin, what would happen? (hint - look at slide with cell fusion experiments) The G1 cell would complete mitosis with daughter cells that have 18 chromosomes each The G1 cell would enter mitosis but arrest at the spindle checkpoint because the chromosomes were not properly replicated The G1 cell would complete mitosis with daughter cells that have 36 chromosomes each The G1 cell would go through S phase first, and then mitosis, and would have daughter cells with 36 chromosomes each QUESTION 8 If a cell contains a mutation in the protein FtsZ, what process would be affected? O Septation Cytokinesis ODNA synthesis Cohesin cleavage QUESTION 9 A pharmaceutical company is attempting to design a drug to treat cancer. A researcher suggests making a compound that would inhibit the action of Rb. Would this be successful? No, because Rb is a tumor suppressor gene and functions to inhibit the action of cell cycle regulatory proteins. Inhibition of Rb would release inhibition of the cell cycle, worsening the disease No, because Rb is an oncogene, and functions to activate the action of cell cycle regulatory proteins. Thus, a drug that inhibits Rb would activate cell cycle progression and worsen the disease. Yes, because Rb is a tumor suppressor gene and functions to inhibit the action of cell cycle regulatory proteins. Thus a drug that inhibits Rb would activate cell cycle inhibition.

Answer 1

1. The G2/M cyclines would check if DNA is replicated and rest things are in place. When this cycline is injected in G1 phase, it detects that still DNA is not replicated. Hence it wont allow mitosis to initiate. The cell would pass through S phase, and then goes into mitosis. Option D is correct.

2. FtsZ is the most important protein in septal ring (Z-ring) formation during cell division. Mutation in ftsZ forms long filaments with no septa formation or cell wall formation between newly formed cells. Option A is the answer.

3. Retinoblastoma , Rb protein (pRb) is responsible for a the G1 checkpoint, blocking S-phase entry and cell growth. It is called tumor suppressor gene.   It regulates cell division, and does not allow faulty mutations to carry forward by mitosis. Hence it acts as negative regulator of cancer. Inhibiting Rb would mean de-regulating the cell division and increasing the incidence of cancer. Hence the idea is not viable. Option A is the answer.