Oncogenes Flashcards
Viral induction
Virus goes in front of oncogene and tells RNA to make more protein
Viral induction example
gag-pol-env
Activating mutation
Caused by gene instability
Examples of activating mutations
Ras can’t disconnect from GTP in pancreatic cancer
EGFR doesn’t need binding
What does activation of the Kras oncogene cause?
Ras is constantly bound to GTP and causes growth and proliferation
How can DNA damage be imaged?
Fluorescently tagged antibody is tagged onto antibody that responds to damage
Names some kinases that respond to DNA breaks
ATM phosphorylates Chk2
ATR phosphorylates Chk1
_____ localises to DNA damage
_____ is already present but phosphorylates upon DNA damage.
53bp1
yh2ax
CDK order
4221
Cyclin order
DEAB
Both cancerous and precancerous cells have DNA damage. What is the difference between them?
mutation of p53, ATM or Chk2
What causes DNA damage in precancerous cells?
Oncogene activation
What can be added between replication cycles to compare them?
Fluorescent nucleotides
Fluorescent nucleotide examples
Chlorodioxiuradine replaces thymine
IDU
Oncogene expression causes ________ to start early.
S phase
Where are the normal origins of replication (constitutive origins)?
Intergenic regions
G1, S
What effect does expression of oncogenes have on origins?
Extra origin within a gene
Transcription-replication conflicts
Encounters between DNA polymerase and RNA polymerase
What can cause a replication fork to collapse?
Stalled transcription can lead to conflicts when a replication fork approaches
How can R loops form?
If RNA helicase is functional while there are other transcription/splicing errors, unwound RNA can bind to complementary DNA and form R loops
What is the effect of R loops
Inhibits transcription complex and gets stuck
How does translocation occur?
Unrelated DNA breaks joined together
What are some effects of oncogene expression?
Normal replication decreases
Truncated replication increases
New origins fire (cell can’t use its normal origins)
Truncated replication
Replication stops early resulting in a partial sequence of the DNA fragment
When does phosphorylation happen?
Post transcription
When does ubiquitylation happen?
Post translation
____________ add a phosphate group and ____________ remove a phosphate group.
Kinases
Phosphatases
Describe how auto phosphorylation occurs
2 isoforms phosphorylate each other
Proteosomes function
Degrades proteins into reusable amino acids
