Cancer Cell Cycle Flashcards
What 3 ways do cells control their proliferation?
- In sequence
- In timing
- In response to external signals
How do cells control proliferation
By controlling the activity if their proteins
Proteins can be switched on and off (activate or deactivate) by:
- Phosphorylation
- Dephosphorylation
What is phosphorylation?
The transfer of a phosphate group from ATP to the OH group on a protein. This is done by a protein KINASE.
What is dephosphorylation?
Removal of the phosphate group from a protein. This is done by a phosphatase enzyme.
Both phosphorylation and dephosphorylation can activate or deactivate the protein depending on where the phosphate is added or removed? True or False
True
How do cells control the activity of their proteins?
- Phosphorylation/Dephosphorylation
- Make more proteins / Inhibit and degrade proteins
What happens when proteins are switched on to make MORE proteins?
De novo synthesis occurs from mRNA (to make more proteins) and transcription and translation occurs.
Proteins can be switched off by binding to an inhibitory protein. Why?
It keeps the protein inactive as it may be blocking the active site or part of the protein that it needs to function.
How does degradation (getting removed) of proteins work?
- Targeted degradation can occur by the attachment of one or more UBIQUITIN (Ub) (which are small regulatory proteins) by a Ubiquitin ligase.
- This signals that the protein has to go to the proteasome for degradation and recycling of components.
Inhibitory proteins inhibit the function/activity of other proteins that they bind to. True or False
True
Protein activity can be altered by:
1. Making new protein
2. Targeting protein for degradation
3. Binding to inhibitory proteins
4. All of the above
- All of the above
What are the 3 proteins that control cell cycle control points
- Cyclins
- Cyclin dependent kindness (CDKs)
- Cyclin kinase inhibitors (CKIs)
What are Cyclins
Cyclins are present in a cell at any one time is determined by what stage of the cell cycle you’re at. (Cyclin proteins cycle through the cell cycle).
What are Cyclin dependent kinases (CDKs) ?
They’re kinases (catalyse phosphorylation of other proteins) and cyclin dependent and these kinases can’t function unless they’re bound to their cyclin partner to activate kinase activity.
