cancer

• what is cancer


  genetic disease from a series of mutations where cells divide in an uncontrolled, autonomous manner
• what is a tumor?


  repeated rounds of mutation and proliferation > clone of malignant cancer cells
• how is cell growth, division and survival regulated?


  extracellular signal molecules, intracellular programmes

  e.g apoptosis and increased cell division (if increased cd and normal a, tumor forms)
• describe the 3 extracellular signal molecules that control cell growth(M, G, S)

  Mitogens- stimulate cell division as (recieve info from outside that cell cycle can go forward) by triggering G1-Cdk that prevents intracellular controls blocking progress through cell cycle

  Growth factors- stimulate cell growth by synthesising proteins and inhibiting their degradation

  Survival factors- suppress apoptosis
• example of receptors mutationthat can cause cancer

  (mutation of any component of a cell signalling pathway may lead to cancer)

  (a) Normal receptors exhibit tyrosine kinase activity only after a growth factor has bound to them (b) Some oncogenes encode mutant receptors whose tyrosine kinase is permanently activated (c) Other oncogenes produce normal receptors but in excessive quantities, which leads to excessive receptor activity
• features of cancer cells


  genetically unstable, much higher sugar metabolism, abnormal ability to survive stress and DNA damage
• what is an oncogeneand Proto-oncogenes. How do mutations act?

  a gene whose protein product promotes cancer, generally cs mutations in the proto-oncogene(normal prior tom)> overactive or overproduced proteins ***

  Proto-oncogenes generally regulate cell growth, cell division, cell survival, or cell differentiation.

  
  

  act in dominant manner as only single mutation is needed to promote cell transformation
• what is a tumor suppressor gene?


  A gene that encodes a protein that regulates cell growth and prevents the formation of tumors.

  acts in recessive manner as need 2 mutations to inactivate both gene copies (the loss of this gene increases liklihood of cancer)
• p53 protein. What if mutated?


  tumor suppressor gene. If there's DNA damage, p53 will be activated leading to cell cycle arrest or apoptosis.

  If mutation(2 cs recessive), cancer cells will survive and proliferate cs cell cycle won't be arrested