InC. elegans, the cell death defective mutants (ced1, ced2, ced3, ced4, ced9) have been isolated. Ced1 and Ced 2 are involved in digesting and removing dead cell body (after the cells have been killed). In loss of function ced1 or ced 2 mutants, the dead cells (with enlarged nuclei) remain in the body of the worm and can easily be seen under a microscope.

(1). How will you design a mutagenesis screen to isolate mutations in genes that control programmed cell death? Describe the two possible phenotypes?

(2). Ced9 inhibits programmed cell death, what wouldced1; ced9double mutant phenotype be with regard to the dead cell body and the mutant viability (take a guess)?

(3). Ced3 is required to execute the killing of a cell. What wouldced1; ced3double mutant phenotype be with regard to the dead cell body and the mutant viability (take a guess)?

(4). Humans have corresponding (equivalent) genes to control programmed cell death. What are the names of human homolog for Ced9 and Ced3 respectively?