Term
| What initiates normal cell replication? |
|
Definition
| GF binding to and activating its receptor => activation of signal-transduction proteins. |
|
|
Term
| What causes DNA transcription that promotes entrance to the cell cycle? |
|
Definition
| Signal tranduction thru the nucleus => activation of nuclear transcription regulatory factors. |
|
|
Term
|
Definition
| transient intracellular signal transduction |
|
|
Term
| How are Ras proteins activated? |
|
Definition
|
|
Term
| What does activated Ras stimulate? |
|
Definition
| MAP kinase cascade => nuclear signals for proliferation |
|
|
Term
| What binds to Ras to inactivate it & therefore terminate signal transduction? |
|
Definition
| GTPase-activating proteins (GAPs) (enhance GTP hydrolysis) |
|
|
Term
| Which GAP specifically is important in the termination of Ras protein signal transduction? |
|
Definition
|
|
Term
| Does Ras need GDP or GTP for activation? |
|
Definition
|
|
Term
| What does MYC encode for? |
|
Definition
| nuclear protein integral to both cell proliferation & apoptosis |
|
|
Term
| What are the 2 ways MYC can be activated? |
|
Definition
1) with GF binding GF receptor => mitogenic signal transduction to the nucleus
or
2) without GF stimulation |
|
|
Term
| What happens in MYC is activated without GF stimulation? |
|
Definition
|
|
Term
| How does MYC induce transcription activation? |
|
Definition
| MYC-MAX protein forms and binds to DNA |
|
|
Term
| What 2 things must be transcriptionally activated to enter the cell cycle? |
|
Definition
|
|
Term
| What are the 3 cell cycle regulators? |
|
Definition
cyclins
CDKs (cyclin-dependent kinases)
CDK inhibitors |
|
|
Term
| How do CDKs become phosphoylated & activated? |
|
Definition
| inactive CDK binds to cell cycle-specific cyclins |
|
|
Term
| How do activated CDKs promote progression through the cell cycle? |
|
Definition
| they phosphoylate key proteins necessary |
|
|
Term
| What is bound to the hypophosphorylated retinoblastoma (RB) protein to inhibit it's function in G0 & G1? |
|
Definition
| E2F transcription factor complex |
|
|
Term
| When in the cell cycle do organelles double in number? |
|
Definition
|
|
Term
| What leads to the phosphorylation of RB in G1? |
|
Definition
| synthesis of cyclin D & cyclin E => phosphorylated D/CDK & E/CDK |
|
|
Term
| What causes the dissociation of E2F from RB & transcriptional activation of E2F-targeted genes in G1? |
|
Definition
|
|
Term
| What happens in S phase of the cell cycle? |
|
Definition
| nuclear DNA is replicated |
|
|
Term
| What cyclin & therefore cyclin/CDK complex is formed in the S phase of the cell cycle? |
|
Definition
|
|
Term
| When in the cell cycle are new membrane formed in preparation for cell division? |
|
Definition
|
|
Term
| What is done in G2 to initiate mitosis? |
|
Definition
| cyclin B synthesis => B/CDK |
|
|
Term
| What are the 5 phases of mitosis? |
|
Definition
1)Prophase
2)Prometaphase
3)Metaphase
4)Anaphase
5)Telophase |
|
|
Term
| What characterizes completion of mitosis? |
|
Definition
| Removal of phosphate groups from RB which regenerates hypophosphorylated form |
|
|
Term
When is the restriction point in the cell cycle?
What regulates it? |
|
Definition
| in the middle of G1
regulated by GFs |
|
|
Term
| Where in the cell cycle are the checkpoints for DNA damage? |
|
Definition
|
|
Term
| When is RB phosphorylated in the cell cycle? |
|
Definition
|
|
Term
| What do CDK inhibitor respond to? |
|
Definition
| growth suppressing signals |
|
|
Term
| How do CDK inhibitors block progression of the cell cycle? |
|
Definition
| inactivating cyclin/CDK complexes or inhibiting their formation |
|
|
Term
|
Definition
| check for DNA defect prior to replication |
|
|
Term
| What happens if there's a DNA defect detected at the G1/S checkpoint? |
|
Definition
| increase levels & activation of p53 => up regulation of p21 => cell cycle arrest & stimulation of DNA repair |
|
|
Term
| What happens if there is a DNA defect detected in the G1/S checkpoint, and it's successfully repaired? |
|
Definition
| p53-induced transcriptional activation & formation of self-degrading protein => cell cycle resumed |
|
|
Term
| What happens if there is a DNA defect detected at G1/S checkpoint, but it's not repaired successfully? |
|
Definition
| p53-induced transcriptional activation of pro-apoptotic genes, repression of pro-proliferative & anti-apoptotic genes => apoptosis |
|
|
Term
|
Definition
| check for DNA defect after replication & before separation of the chromatids |
|
|
Term
| What happens if there is a DNA defect detected at the G2/M checkpoint? |
|
Definition
| cell cycle arrest via p53-dependent & independent processes. |
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