Flashcards in CH 9 Cell Communication Deck (22):
What are the four steps of cell signalling?
Receptor activationSignal transductionResponseTermination
Define receptor activation
The signal nods to a receptor which is then activated
Define signal transduction
Signal is transmitted to the interior of the cell by a signal transduction pathway
Cell responds for example by activating an enzyme or turning on transcription
The response is terminated so that new signals can be received
What is the most important factor for communication in bacterial cells?
The number of cells (cell density)
What are the four types of signalling and how far does the signal travel?
Endocrine - large distancesParacrine - up to 20 cellsAutocrine - cell is the signalling and responding cell (self)Juxtacrine - direct physical contact
During endocrine signalling how is the signalling molecule transmitted?
Though the circulatory system
Why do Paracrine signalling cells not signal themselves?
They do not contain receptors
Does juxtacrine signalling cause a confirmational change ?
Define ligand binding site
Location on the receptor to which the ligand binds
Polar molecules require which type of receptors to communicate?
Cell surface receptors
Non Polar molecules require which type of receptors to communicate?
What are the three types of cell surface receptors?
G protein coupled receptorsReceptor kinasesLigand gated ion channels
How are ions able to pass through ligand-gated ion channels?
Confirmational change, changes the shape of the ion channel to allow ones to pass through
What are the three phases of G protein activation?
Alpha subunit is joined by three subunits and G protein is inactiveG protein gets bound by an activated receptor causing GDP to turn into GTP therefore activating the proteinActivated G proteins binds and activates target protein
Explain the amplification of the adrenaline signal
Each activated receptor activates multiple G proteins which activates adenylyl Cyclase enzymesEach adenylyl Cyclase enzyme produce cAMP which activates protein kinase AEach protein kinase A activates multiple protein targets
Explain termination of the G protein signal
Signal molecule detaches from the receptor after a certain amount of timeGTP is converted back to GDP in the G protein Enzymes in cytosol degrade cAMPPhosphotases removes phosphate groups from proteins causing them to become in active
Explain receptor kinase activation and signalling
Signalling molecules bind to receptor causing a confirmational changeThis creates a dimer Each member of the receptor pair attaches phosphate groups to the other member The phosphate groups provide binding sites for intracellular signalling proteins
Explain the MAP kinase pathway
Signalling molecule binds to inactive receptor causing it to be come active this activate the Ras proteinRas protein activates kinase 1 converting ATP to ADP which activates kinase 2 so fourth down to kinase 3 Causing change in gene expression