7. Cell Adaptations Flashcards
What does the size of cell populations depend on?
Rate of cell proliferation, cell differentiation, and cell death by apoptosis.
What regulates normal cell proliferation?
Proto-oncogenes.
What are the final outcomes of cellular adaptations?
Survive - resist apoptosis.
Divide - enter cell cycle.
Differentiate - take on specialised form and function.
Die - undergo apoptosis.
What forms of cell to cell signalling are there?
Hormones, local mediators, and direct cell-cell or cell-stroma contact.
What are growth factors involved in?
Cell proliferation.
How do growth factors regulate cells entering the cell cycle?
Bind to specific receptors, stimulate transcription of genes that regulate entry of cell into cell cycle.
What do growth factors affect?
Cell proliferation and inhibition, locomotion, contractility, differentiation, viability, activation, angiogenesis.
What are four types of important growth factors?
EGF - epidermal growth factor.
VEGF - vascular endothelial growth factor.
PDGF - platelet derived growth factor.
GCSF - granulocyte colony-stimulating factor.
How is growth in the cell cycle increased?
Shortening the cell cycle, conversion of quiescent cells to proliferating cells by making them enter the cell cycle.
What happens in each of the steps of the cell cycle?
G1 - gap 1, presynthetic, cell grows.
S - DNA synthesis.
G2 - gap 2, premitotic, cell prepares to divide.
M - mitosis.
What is the most critical checkpoint of the cell cycle?
R (restriction) point towards the end of G1. Most commonly altered in cancer cells.
What controls the cell cycle?
Cyclins and CDKs.
What are labile cell populations?
Stem cells divide persistently to replenish losses.
What are stable cell populations?
Stem cells normally quiescent or proliferate very slowly, but proliferate persistently when required.
What are permanent cell populations?
Stem cells present, but cannot mount an effective proliferative response to significant cell loss.
