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cell signalling
biochemical communication
| Question | Answer |
|---|---|
| what is cell signalling | pathway where the signalling cell sends a SIGNAL to the target cell - 2 types - spatial = a developmental signal TEMPORAL =when the target cells chemistry changes for an appropriate period |
| where can a receptor bind on a cell | 1. on cell membrane2. within the cell |
| what does the signal receptor complex cause? | 1. transformation/transduction into a molecular form2. relay - signal transported from site of entry to where the response is produced3. amplification - signal more amplified, ie. more stronger4. distribution - to different intracellular struct. |
| nature of response to external signals | electrical / chemicalelectrical = movement of ions across pm, rapid response (millisec), predominant in cnschemical = enzyme activity changes, change in mrna prod. |
| types of properties of molecules for extracellular signalling | lipid soluble = endocrine, paracrine, autocrinewater soluble = hormones, cytokines, growth factors, neurotransmitters |
| what are receptors | are proteins which span the membrane or can be found intracellularly |
| receptors fro lipid soluble signalling molecules | -lipolytic hormones with intracellular receptors eg. steroids - alters gene expression-lipolytic hormones with cell surface receptors ie. prostaglandins, lx, lt, from arachidonice acid- catalytic cytosoliceg. no/co |
| receptors for water soluble signalling molecules | -ion channel linked - transforms chem 2 electrical signal. electrical pm potential changes, eg. nerve cells- g protein linked receptors - g protein complex + effector 7x membrane spanning proteins - has alpha,beta, gamma subunits |
| is g protein a second messenger? | yes - binds to site of action, activates adenylyl cyclase and forms camp |
| how is camp eliminated? | using camp phgosphodiesterase |
| what is the function of camp dependant protein kinase | phosphorylation |
| action of phospholipase c? | PIP2 --DAG + IP3 the ip3 is released into cytosol then to er, opens ca2+ channels. increase in ca2+ and DAG activates protein kinase c and binds to ca2+ calmodulin kinase - which then phosphorylates proteins |
| high concentration of ca2+ is in.... | er + mitochondria |
| low concentration of ca2+ is in.... | cytosol |
| how is the concentration gradient of ca2+ maintained? | 1. na/ca2+ exchange mech with low affinity n high capacity2. ca2+/proton atpase dep protein - high aff - low capacity3. ca2+/atpase pump - pumps into cytosol then to er |
| mechanisms which change intracellular ca2+ | - hormones bind to ca2+ channels - increase membrane permeability-ca2+ is mobilised from er + mit- hormones increase ca2+ influx by changing memb potential |
Created by:
ahmeda101
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