Checkpoints and Cancer

1. 5c & d: Checkpoints in the Cell
& Cancer

2. Checkpoints
 While preparing for division, a cell does a self-check to see if
everything is proceeding as normal.
 A cell will not divide if:
 There are not enough nutrients available to support continued
growth
 The DNA has not been replicated
 The DNA is damaged
 If an issue is detected the cell either repairs or destroys itself.

3. Checkpoints
 Chromosomes attached to
spindle fibers?
 Chromosomes split evenly
during anaphase?
 Enough nutrients to
support cell?
 Damaged DNA?
 DNA replicated?
 Damaged DNA?

4. Cancer
 If a mutation occurs in a gene that produces instructions for a
checkpoint protein, cell cycle control will be lost.
 Damaged cells divide without control – uncontrolled division
is called cancer.
 Instead of division stopping after a single layer of cells is
produced, cancer cells grow in multiple layers called a tumor

5. Cancer
 Cancer cells are abnormal and do not carry out the normal
functions of the tissue where the tumor has grown
 Cancer cells have large abnormal nuclei due to uncontrolled
cell division from lack of regulation by checkpoints
 Cancer cells attract blood vessels to supply the tumor with
nutrients for continued growth
 Some cancer cells can enter the blood stream and spread to
other parts of the body and form new tumors – Metastasize