Question

You are examining two mutants where you are able to quantify the amount of DNA - shown below. One of these mutants has a loss of function in the APC and the other mutant has a loss of function in Ras. Match the graph with the mutant and EXPLAIN what about the graphs indicated that it was this mutant - process of elimination is not acceptable.

1) You are examining two mutants where you are able to quantify the amount of DNA- shown below. One of these mutants has a loss of function in the APC and the other mutant has a loss of function in Ras. Match the graph with the mutant and EXPLAIN what about the graphs indicated that it was this mutant-process of elimination is not acceptable. WT A B Percent of cells 25% 50% 75% 100% 0 25% 50% 75% 100% 25% 50% 75% 100% O 40 2- 2. 4n 2n Mos of DNA Mass of DNA Mass of DNA

Answer 1

Graph A - This graph shows loss of function of APC protein

Graph B- This graph represents loss of function of Ras protein

Explanation: APC is a tumour suppressor gene which controls cell growth and proliferation. If APC gene became mutated the cells grows rapidly without any control and hence number of cells increases in huge amount. Graph B represents huge amunt of diploid cells which describes the situation. So graph B represents situation where APC gene is mutated.

Ras is a tyrosine receptor kinase induced signalling molecule which controls actin cytoskeletal integrity, cell proliferation, cell differentiation, cell adhesion etc. S if Ras protein became mutated, the roper division of cell material including chromosomes will not occur and as a result proportion of tetraploid cells will increase. Graph C represents this situation and hence it best represents the situation where Ras gene is mutated.