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31 Cards in this Set
- Front
- Back
- 3rd side (hint)
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define apoptosis
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a specific type of programmed cell death
that occurs by set pathways and has set characteristics (controlled and normal in development) |
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species where much apoptosis research was done?
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C. elegans
Nematode worm contains 959 cells |
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symptoms of apoptosis?
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cell shrinkage
cytoskeleton collapse nuclear envelope breakdown (lamins) chromatin breakdown changes in cell surface |
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Where does Caspase get its name from?
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C = cystiene (at active site)
asp = aspartic acid ase = enzyme |
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What is a Caspase?
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an inactive PROCASPASE
need cleaving to become active |
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two classes of caspase?
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Initiator = cleaves other caspase's
Executioner (effector) = cleaves other Caspases AND target other protein cells |
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Extrinsic apoptosis?
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Killer Lymphocytes
have ligand which binds with cells death receptor actives caspases |
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Intrinsic apoptosis?
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release of proteins from Mcd
Mcd? Random! Explain... |
healthy Mcd retain their proteins.
Apoptotic Mcd release their contents into the cell. Cyctochrome C is your protein (normally found in inter-membrane space) |
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what else is cytochrome c used for?
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Cellular respiration... electron transporter in the ETC
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Intrinsic apoptosis. The dets?
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activation of apaf1 (apoptotic protease activating factor) by chromosome c
formation of CARD (Caspase Recruitment Domain) recruitment and activation of PROCASPASE 9 Cleavage and activation of Caspase cascade |
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Step 1 Signal Transduction in Apoptosis?
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Inactive BH123 aggregate in Mcd membrane and form pore to release proteins
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Regulation of Step 1 Signal Transduction in Apoptosis?
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1= Bcl2 protein prevents aggregation of BH123.
2= BH3 inactivates Bcl2 and triggers aggregation |
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What activates BH3?
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Many signals but one is...
p53 Oh yea, whats that again? |
p53 is a transcription factor
important during DNA repair but you know that |
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how does p53 work?
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it binds p21 gene
p21 gene encode a CKI, a Cdk Inhibitor protein. This CKI then inactivates Cyclin and blocks the cell cycle. But how does that help with apoptosis? |
it also binds gene for BH3 protein. Ba-jingo!
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2 properties of cancer
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1- cells REPRODUCE in defiance of cell cycle controls
2- cells INVADE and colonise territories normally reserved for other cells |
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Benign?
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Only uncontrolled cell division
(not yet invasive) |
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Malignant?
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acquire the ability to invade surrounding tissue.
Leaves the lumen and breaks through the basal lamina |
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Metastases?
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Secondary tumors due to primary being malignant.
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what % of cancer is lifestyle or environment related?
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80%
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% of deaths related to cigarette smoking?
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25% of all cancer deaths
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3 ways a cancer can develop, i.e defeat cells growth mechanisms?
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1- Hereditary disposition
2- mutation 3- viruses |
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name two oncogenes
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Ras - signals the MAP kinase cascade
Myc - a regulator gene that codes for a transcription factor Both are in the G1 cyclin production pathway |
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what is an oncogene
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a gene that has the potential to cause cancer.
In tumor cells, they are often mutated or expressed at high levels |
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upregulated?
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An increase of a cellular component is called upregulation
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recap what p53 does
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activated p53 binds the p21 gene which encodes the CKI
This CKI inactivates cyclins and blocks the cell cycle |
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excessive production of Myc
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leads to transcription of Arf
Arf inactivates the Mdm2 Mdm2 is a negative regulator of the p53 tumor suppressor leads to an active p53 protein Need other mutation to cause cancer |
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what is Rb's role
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Rb (retinoblastoma) is a tumor suppression gene and protein
Cell cycle needs E2F transcription factor. Activation of E2F requires inactivation of Rb |
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most important tumor suppressor gene?
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p53
is a transcription factor for 1- DNA repair 2- cell cycle control 3- apoptosis |
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the loss of p53 promotes cancer in 4 different ways...
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1- cells with damaged DNA can continue to divide
2- cells with damaged DNA can escape apoptosis leads to.... 3- allowing division in cells with damaged chromosomes , promoting genetic instability and FURTHER MUTATIONS to occur 4-makes cancer more resistant to anti-cancer drugs |
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HPV?
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Human PAPILLOMAvirus
causes cervical cancer a fucken virus! |
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How does HPV work?
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Jams the accelerator: inactivate the Rb protein which then cant inhibit E2F (promotes cell division cycle)
Kills the brakes: Inactivates p53, blocking tumor suppression |
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