Cancer L2 - Oncogenes and tumor suppressor genes Flashcards
there are two main types of genes that play a role in cancer what are they?
oncogenes and tumor supressor genes
cancer occurs/genes there are 4 types of chromosomal mutations, what are they?
- deletion: a particular base is deleted
- dupplication: a particular base pair is duplicated
- inversion: inversion is when a base pair attaches to a different region of the chromosome
- translocation: are two chromosome crossing and swaping genes
modifications of DNA that switch specific gene expressions on/off are known as what?
epigenetic mechanisms
the 4 type of chromosonal mutations are an example of epigentic mutations
the number and visual appearance of the chromosomes in the cell nucleir of an organism or species is reffered to as what?
karyotype
……………… are genes that when not affected by mutation help regulate the balance between cell proliferation and apoptosis.
mutation on these genes can lead to the development of cancer
(what is the missing word)
cancer critical genes
there are two main classes of cancer critical genes, what are they?
- proto-oncogenes: where a gain of function mutation can drive a cell towards caner.
mutant, overactive, or over-expressed forms of these genes are called oncogenes
- tumor supressor genes: where loss of function mutations can contribute towards cancer e.g. TP53
which cancer critical gene would contribute to cancer with a loss of function
tumor supresor gene
which cancer critical gene would contribute to cancer with a gain of function
oncogenes
disruptions in key pathways is common to many cancers
three key pathways more than often found to be affected in tumors
P53 pathway: P53 is produced when damage to the DNA is detected
what are the 3 main functions of P53
- produce P21, which is responsible for cell arrest by inhibiting CDK and Cyclin
- promotes DNA repair
- produces proteins for Apoptosis
which protein is responisble for cell arrest by the inhibition of CDK and Cyclin
P21 is responsible for cell arrest, however P21 is activated by P53
disruptions in key pathways is common to many cancers
three key pathways more than often found to be affected in tumors
the Rb pathway (retinoblastoma) results in the inactivation of the E2F.
what happens when E2F is inactive
E2F is a transcriptase factor and is responsible for reading the DNA, to produce proteins.
E2F is found during the g1 phase of the cell cycle
if there is a mutation of the retinoblastoma protein or the gene that produces the protein. this will result in the failure of Rb protein inactivating the E2F .
as a result the mutated cell will be allowed to move to the next cycle.
disruptions in key pathways is common to many cancers
three key pathways more than often found to be affected in tumors
what is the function of the RAS pathway and how is this affected when somene has cancer.
the function of the RAS pathway is to activate the nucleus to activate the growth genes.
growth factors activate the GFR by binding on to it and this causes phosphorylisation
this pathway transmits signals for cell growth and division from the outside of the cell into the cell.
soneone with cancer this pathway is constantly on (oncogene activated)
P53 is encoded by which gene
TP53
P53 produces P21 which results in the inhibition of CDK and Cyclin causing cell cycle arrest.
what happens to the cell once it is arrested
cell enters G0 stage in the cycle.
at this stage it can undergo repair or apoptosis
when damaged DNA is detected, protein kinase activates P53
active P53 then binds where
active P53 binds to the regulatory region of the P21 gene
