Molecular Cell Biology Flashcards
(28 cards)
Which cyclin/CDK is the link between the cell cycle and the external environment?
Cyclin D/CDK 4
What does INK4 the CDK inhibitor protein inhibit? And what is the consequence?
It binds CDK4 therefore cyclin D can’t bind and hence Rb isn’t phosphorylated and therefore cannot bind E2F therefore transcription cannot occur.
Which inhibitor protein binds the cyclin (E/A) - CDK 2 complexes?
KIP
What type of inhibitor is INK4?
binary
What type of inhibitor is KIP?
ternary
What does KIP prevent?
Activation of cyclin (E/A)-CDK2 complex
True of false - some cells spend entire life in G0 phase and some divide infrequently.
True - hepatocytes = infrequently, neutrons = lifetime
Do cancer cells have Restriction point?
No
Do cancer cells respond to contact inhibition?
No
What is an example of a positive GF?
E2F
What is an example of negative GF?
TGF-beta
Do cancer cells have limited replicative life span?
No - they can remake telomeres when eroded.
What is apoptosis?
Programmed call death
What can the malfunction of apoptosis lead to?
Cancer (TNF produced by macrophages activates extrinsic pathway), neurodegeneration, AIDS (HIV deactivates Bcl-2), ischemic stroke, autoimmune (LUPUS)
What happens if there is too much apoptosis?
Loss of SC, problems with regeneration.
What happens there is too little apoptosis?
Too many SC, problems with regeneration and function - leukaemia.
What is necrosis?
Lethal cell injury and accidental cell death in living organisms.
What are the characteristics of apoptosis?
No loss of membrane integrity, shrinking of cytoplasm and nuclear condensation, mito release death signals, aggregation of chromatin at nuclear membrane.
What are the characteristics of necrosis?
Loss of membrane integrity, swelling of cytoplasm and mito, total cell lysis, disintegration of organelles, no vesicle formation.
What is the important of apoptosis in adults?
Tissue remodelling/maintenance, loss of endometrium at start of menstruation, maintenance of organ size and function by balancing proliferation.
What is the importance of apoptosis in development and morphogenesis?
Eliminates excess cells, eliminates non-functional cells.
What is the importance of apoptosis in disease?
Viral infection - CTLs kill infected cells.
Immune system - after prolonged immune response body removes effector cells.
DNA damage - damage to genome –> cancer
Cancer therapy induces apoptosis.
What are the +ve signals that make a cell commit suicide?
continuous stimulation from other cells, and adhesion
What are the -ve signals that make a cell commit suicide?
more free radicals and oxidants, DNA related inducers e.g. UV light, physiological activators e.g. removal of GF.
