9 - Regulation of Proliferation I Flashcards
If the cell is not the correct size, what is it missing?
more cytoplasm, more cell membrane, enough organelles
Why aren’t cells such as neurons and cardiac cells ever tumors? How can this change?
they don’t divide | can change via viral infection
What stages does Interphase consist of?
G1, S, and G2
What does Rb do if the cell cycle is off?
binds to E2F = no transcription = no entry into S-phase
What does Rb do if the cell cycle is on?
releases E2F = transcription = early into S phase
What is the effect on the cell cycle if both copies of Rb are mutated? What type of gene is Rb?
no cell cycle arrest | tumor suppressor
When in the cell cycle is Rb phosphorylated?
late G1
What happens when Rb is phosphorylated?
conformational change = release E2F
What does hypo-phosphorylation mean in terms of Rb?
under phosphorylated »_space;> inhibiting and active Rb
What does hyper-phosphorylation mean in terms of Rb?
over-phosphorylated »_space;> not inhibiting = inactive Rb
What is CDK?
cyclin-dependent kinase = needs cyclin
What transcription factor helps make cyclins?
E2F
In which 2 blastomas are Rb dysregulation found?
osteosarcoma | retinoblastoma
What are two ways an individual can have loss-of-function mutations in tumor suppressor genes?
sporadic | hereditary
What are sporadic mutations?
non-hereditary, picked up along the way
What are hereditary mutations?
born with at least one copy mutated, can pick up second one along the way | most people with this will develop tumors
When can second mutations occur?
during strand invasion (cross-overs)
What does the Ras gene do?
GTP protein that activates the MAP-Kinase cascade »_space;> turns on E2F
What kind of gene is Ras?
proto-oncogene
What happens if Ras was mutated?
cannot hydrolyze GTP into GDP = GTP stays in Ras »_space;> signal stays on = constantly activates domino effect in absence of growth factor
What amino acid change is due to the mutation in Ras?
Gly to Val
What is c-myc?
transcription factor that can make more E2F and other cell cycle genes
What does c-myc stand for? What turns c-myc on?
cellular myc gene | turned on by the Ras/MAPK cascade
What are mitogens?
proteins that induces cell division
What is c-myc called when it is hijacked by viruses?
v-myc (v = viral)
What are the effects of translocating the c-myc gene?
can be turned on if translocated next to an active promoter
What happens if c-myc was turned on and then turned off? And then turned on again?
off = cells differentiate | back on = cells die
In which stages of the cell cycle do we have 4N chromosomes?
G2 and beginning of M-phase
What happens to the genome at the end of apoptosis?
genome gets degraded into fragments (smaller than 2N)
What are the 2 types of drugs (discussed in class) that can affect the cell cycle phases?
G2 arrest drugs | drugs that can cause cell cycle arrest and lead the cell to apoptosis
What is PI staining used for?
stains DNA to observe DNA content of cells
What does BrdU stain?
stains uracil
What is the purpose of BrdU staining?
can indicate where the cell is in S-phase
What is the purpose of using antibodies in BrdU staining?
can tell you if the cells are in M or G2 phase
