Cancer

What is multi-step carcinogenesis?

Produces sequential copies of mutant cells

with increasingly cancerous phenotypes

requires 2-12 mutations

What are tumour suppressor genes and proto-oncogenes/oncogenes?

Code for proteins that stop cell proliferation

Code for proteins that usually promote proliferation (CDKs, receptors) mutated is oncogene

need mutation in both for cancer

How do proto-oncogenes affect MAP kinase signalling cascades?

Receptor has increased activity/signalling

Ras is unable to lyse GTP so always active

Raf then always activates downstream molecules

over production of cyclins and more cyclin-CDK complexes

How do mutated tumour suppressor genes affect cell cycle?

Rb can be permanently inactivated so E2F is always active preventing S-phase

p53 may also allow cells with DNA damage to pass checkpoint

What is metastasis?

Spread of cancer from one organ to another, different cancers spread to specific regions