BIOLOGY November 29, 2013
Growth factors and hormones promote cell division
1) Growth factor or hormone binds to a receptor, leading to receptor activation
2) Receptor activation causes a cascade of interactions between intracellular signaling
proteins thereby activating them.
3) The final protein in the signal transduction pathway activates transcription factors in the
nucleus. This leads to the transcription of genes that promote cell division.
- Cancer is the loss of cell cycle control
o Cells divide continuously and uncontrollably
o Rapid growth and division results in a mass of cells that can interfere with body
- Chemotherapy targets cell cycle proteins to stop cell division.
o Taxol freezes the mitotic spindle by preventing de-polymerization of
microtubules. Mitosis can’t proceed past metaphase
Failure of checkpoints causes cancer
- Two general types of defects:
o 1. Defec