Controlling cells Flashcards
(23 cards)
Describe the general model for cell signalling.
Reception of signal. Transduction. Cellular response.
What is signal transduction?
receiving info into cell and acting on it to make choices.
What are the 5 crucial functions s signalling cascade?
Transduce. Relay. Amplify. Distribute. (modulate)
True or false - cells respond to specific signals due to specific receptors.
True
True or false - many signalling proteins act as molecular “switches”
True
What are the two classes of extracellular signalling molecules?
Small / hydrophobic. Hydrophilic.
What is an example of a hydrophobic single molecule?
Steroid hormones
what are steroids similar in structure to?
Cholesterol
How do steroid hormones signal?
through intracellular receptors.
What is small signal?
NO - unstable gas, small and uncharged
How does NO signal?
Through cytoplasmic receptor.
What are the 3 categories of enzyme-linked receptors?
Receptor tyrosine kinases, cytokine receptors, TGF-beta type receptors.
What type of ligands bind to RTKs?
soluble or membrane bound peptide, protein hormones e.g. insulin.
What have some RTKs been found to do in cancer cells?
send proliferative signals to cells in absence of signal.
How are RTKs activated?
Phosphorylation of target protein and self.
What do RTKs stimulate?
Signalling complexes - can be 10-20 downstream signalling molecules e.g. Was.
How are RTK complexes disassembled?
by protein tyrosine phophatases.
Describe the RTK –> Ras pathway.
Activates Ras protein by ran bound GDP–> GTP. Was activates cascade of MAP kinases.
Describe the RTK –> Pi-3-kinase-ATK pathway
Cascade of phosphorylation. Ask = survival signal and stimulates cell growth (activates Tor.)
What are cytokines and what do they do?
Small secreted proteins. control growth and differentiation of many types of issue.
How do cytokines signal?
in a direct pathway to the nucleus. Binding of cytokine, activates STAT regulatory protein which dimerises and migrates to nucleus.
What does STAT do?
Activate transcription
What is the net effect of NOTCH signalling?
A small group of cells are segregated from an equivalent field.
