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cell signalling

biochemical communication

QuestionAnswer
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 on 2009-04-18



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