Regents Biology Mitosis & Cancer: When Making New Cells Goes Terribly Wrong!

Regents Biology When is mitosis a good thing?  When you have to add or replace cells  growth & development  repair  replacement

Regents Biology Regulation of Cell Cycle

Regents Biology Cells will not divide if…  there are not enough nutrients to support cell growth  DNA is damaged  DNA has not been replicated …cell will be repaired / destroyed.

Regents Biology When is mitosis a BAD thing  When cells reproduce & they are not needed  these cells take over organs, but don’t do the right job  they just keep making copies  cancer  damages organs

Regents Biology Growth of a tumor

Regents Biology Healthy Cells  grow in a single layer  stop dividing when they receive messages from neighbouring cells Cancer Cells  do not respond to messages from neighbouring cells…continue to divide  start to grow in multiple layers that form a tumor

Regents Biology Why would cells just make copies?  If DNA gets damaged, cells stop listening to correct instructions  mutations  Causes of mutations:  UV radiation  chemical exposure  radiation exposure  heat  cigarette smoke  pollution  age  genetics

Regents Biology Tumors  Benign tumor  abnormal cells remain at original site as a lump  most do not cause serious problems & can be removed by surgery

Regents Biology Tumors  Malignant tumor  cells leave original site  carried by blood system to other tissues  start more tumors  damage functions of organs throughout body

Regents Biology Watch how a tumor grows... nesis-lg.mov

Regents Biology Treatments for cancers  Treatments kill rapidly dividing cells  chemotherapy  poisonous drugs that kill rapidly dividing cells  radiation  high energy beam kills rapidly dividing cells side effects

Regents Biology Show what you’ve learned! Assignment: Page 138 Questions14 to18