hallmarks of cancer Flashcards
What is the cell cycle controlled by?
mitogens
growth factors
survival factors
What are mitogens?
stimulate cell division (in the cell cycle)
What are growth factors?
stimulate cell growth (cell mass)
What are survival factors?
suppress apoptosis
Proliferation
increase in cell number
3 major components of the cell cycle?
M phase - mitosis
interphase
checkpoints
M phase
mitosis
cell division
each daughter cell receives a complement of genetic material and organelles identical to that of the parent cell
interphase
the part of the cell cycle where cells grow and replicate their DNA
checkpoints
detect damage to the DNA due to external agents or problems that arise during DNA replication and trigger the DNA damage response
function of the cell cycle
duplicate DNA/chromosomes
segregate copies into 2 identical daughter cells
phases of cell cycle in order
G1 - S - G2 - M
G1 - gap in growth
S - synthesis
M - mitosis
interphase = G1-S-G2
G1 phase of the cell cycle
longest phase
first gap phase
gap between mitosis and S phase
cells half size after mitosis/division
cells adapt and grow during G1
cells CANNOT undergo further division
if cells have poor nutrition/receive an anti-proliferative signal they will enter G1 phase
G0 phase of cell cycle
cells that no longer need to divide and grow become specialised cells
these enter G0 phase - ‘‘cell cycle arrest’’
cell still active - producing proteins, enzymes, motile, secrete
usually permanent but can be reversed
can re-enter cycle if genes reactivated
cell types that cannot leave G0
skeletal
neuronal
liver - but if damaged can reverse this and regenerate
Do cells in G0 express cell cycle regulators like CDKs and cyclins?
NO
What controls G1 phase entry?
mitogens
they release CDKs
S phase
DNA replication before cell division
46 chromosomes are duplicated
daughter cells have ID DNA
must be very accurate
G2 phase
checkpoint
enzymes are activated
trigger point for mitosis
DNA integrity is checked during G2
if faulty DNA is detected the cell cycle prevents it from continuing
M phase
cell division
prophase, prometaphase, metaphase, anaphase, telophase
What ensures DNA is correct during the cell cycle?
DNA checkpoints
What happens if DNA is damaged?
it leads to cell cycle arrest and activtaes a DNA damage response
DNA is repaired before the cell cycle continues
or apoptosis can occur
if DNA damage isn’t repaired mutations can occur leading to faulty cell cycle and cancer can develop
protein that is essential for cell cycle progression between G1-S and G2-M in yeast?
cdc2
-> cell division cycle 2
What do cyclins bind to?
CDKs
-> cyclin dependent kinases
kinase?
enzyme that phosphorylates targets to casue a response
What regulate CDKs?
cyclins
What does the cyclin-CDK complex do?
phosphorylates a set of substrates/targets
targets change during the cell cycle
What do CKIs do?
CKIs bind to cyclin and CDK and distort the active site of the CDK
they insert into the ATP binding site and inhibit CDK enzymatic activity
What are the 2 families of CKIs?
- CDK inhibitory protein/kinase inhibitor protein (Cip/Kip)
- INK4 proteins (inhibitors of CDK4)
examples of cip/kip
p21
p27
p57
examples of INK4 proteins
p16
p15
p18
p19
What do CIP/KIP inhibit?
inhibit CKD1 and 2 complexes
What do INK4 proteins inhibit?
inhibit CDK4/6 directly
What are CKIs specific to?
tissue specific
