Somatic cancer cells often are unstable and divide inappropriately (divide when they should not be dividing). In addition such c
ells often contain losses of some chromosomes and extra copies of other chromosomes. Defects in which of the following may be partially responsible for the aberrant behavior of cancer cells? (Select all that apply.) A)spindle-assembly checkpoint
B)G1/S checkpoint
C)homologous chromosome pairing
D)crossing over
G1/S checkpoint is one of the points in the cell cycle, between growth phase 1 and DNA synthesis phase, where a cell that has been damaged is sensed by DNA repair enzymes and further degraded by apoptosis. In cancer cells, there is mutation in these DNA repair enzymes and thus nothing to correct the cells from dividing even when damaged and thus there is no arrest of division and cells continue dividing