Cancer cells and meiosis Flashcards
size of organ depends on total cell mass dependent o
total number of cells and their size
processes regulated
cell growth, cell division, cell survival
by intracellular programmes and extracellular signal molecules
3 external factors to reach cell from outside - affects progression of cell cycle
mitogen
growing factors
survival factors
mitogen function
stimulate cell division by triggering waves of G1/S-Cdk activity - relieves intracellular negative control
growing factor
stimulate cell growth by promoting protein synthesis and other macromolecules and inhibiting their degradation
survival factors
promote cell survival - suppressing the form of programmed cell death(apoptosis)
social control of cell
tells how cells act
from outside - extracellular signals
cancer cells
cells that no longer respond to social signals
cancer progression
evolutionary process driven by gene mutation(providing cell with competitive advantage)
mechanism of mutated cells
suppresses mechanism of apoptosis
evolution of cancer
initial clone of cancerous cells - additional mutation increase causing generation of diverse sub clones forming cancer cells
Hall marks of cancer cells
organising principles of rationalising complexities of neoplastic disease
hall marks includes
sustaining proliferative signalling, evading growth suppressors etc
hallmarks genome instability
generates genetic diversity that expedites acquisition, inflammation which fosters multiple hallmark functions
features of cancer cells of mutation
- display altered control growth
- contain and accumulate somatic mutation
- single mutation - not enough to change normal cells into cancerous cell
have abnormal to survive stress and DNA damage - create own microenvironment(niche) - evolve
feature of cancer cells of control and spread
- can bypass normal proliferation control - independence of mitogens
- colonise other tissues
- develop gradually from increasingly aberrant cells
- altered sugar metabolism
- genetically unstable
2 genes where mutation stimulates tumour progression
oncogene and tumour suppressor gene
oncogene
act in dominant manner
gain of function
oncogene function
promote cancer - protooncogene - overactive/overproduced
- regulate cell growth, division, survival or differentiation
tumour suppressor gene function
normally restrain cell proliferation or tumour - loss of gene increases causing cancer formation
example of oncogene
activation via mitogen stimulation
process of activation via mitogen stimulation
- mitogens bind to cell surface receptor = initiate intracellular signalling pathway
- activation of small GTPas.Ra which activates MAP kinase cascade, increasing expression of numerous intermediate early genes including gene encoding transcription regulatory protein Myc
Myc in example of oncogene
increase expression of delayed response gene expression which increases G1-Cdk activity which triggers phosphorylation of Rb family of protein
inactivation of Rb proteins
freeing gene regulatory protein E2F
activating G1/S gene transcription including genes for G1/S-cyclin and S-cyclin
