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Transcript of cell communication.ppt
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Cell
CommunicationModules 21 and 22
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Todays Agenda
n 25 minute lecture on Cell communication
n LISTEN only
n Small group work to fill in notes and ask questions
n Class discussion and Review
n Concept Map
n In class quiz
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Cell Communication
Signal: agent whichinfluences a property of
the cell
Receptor: protein whichrecognizes signal and
begin the cellular
response
Why do cells need torespond to signals??
Glucose as a signal in yeast
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How are signals transferred?
1.Direct Intercellular Signaling: via cell junctions from
cytosol to cytosol. Ex. Gap junctions
2.Contact-dependent Signaling: signal molecule is
membrane-bound
3.Autocrine Signaling: cell secretes molecules that bind to
its OWN surface and neighboring cells of same type
4.Paracrine Signaling: secreted signal affects only target
cells in close proximity. Ex. Synapses
5.Endocrine Signaling: long distance via vascular system.
Hormones
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signaling
1.Receptor Activation
signal binds to receptor
2.Signal Transduction
activated receptor stimulates sequence ofreactions: signal transduction pathway
3.Cellular Response
Can: alter activity of enzymes, alter proteinstructure and function, or change gene expression
by regulating transcription factors
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How to ligands Bind?Specific, reversible, rapidly: ligand-receptor complex
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Cell Surface Receptors
Receptors found in Plasma Membrane
3 categories
1.Ligand-gated ion channels
2.Enzyme-Linked receptors
3.G-protein coupled receptors (GPCR)
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Ligand-Gated Ion Channels
Animal, Plant and fungal cells
Ligand Binds-receptor channel opens to allowflow of ions through membrane
Important in nervous system
Can allow Ca+ into cytosol-important for signaltransduction
EX. Acetylcholine Na+ channel
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nzyme- n ereceptors
Found in all living species Extracelluar domain: binds to signal and causes
conformational change
Intracellular domain: catalytic function
Most function as protein kinases
phosphorylate AAs of proteins
EX. Tyrosine Kinase: phosphorylate tyrosine thuschanging structure of protein. Most abundant type
Can mediate direct effects on cytoskeleton
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animation of
RTKs
http://www.wiley.com/college/fob/quiz/quiz21/21-15.htmlhttp://www.wiley.com/college/fob/quiz/quiz21/21-15.htmlhttp://www.wiley.com/college/fob/quiz/quiz21/21-15.htmlhttp://www.wiley.com/college/fob/quiz/quiz21/21-15.html -
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Receptor T i
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Receptor TyrosineKinases receptor tyrosine kinase
recognize various signaling molecules includinghormones called growth factors
stimulate cell growth or division. Ex.Epidermal Growth Factor (EGF)
Receptor Activation results in
1.relay proteins activate protein kinasecascade
2.PKC phosphorylates transcription factors
3.activated transcription factors stimulate gene
http://www.dnatube.com/video/539/Receptor-Tyrosine-Kinase-Activation-and-Signallinghttp://www.dnatube.com/video/539/Receptor-Tyrosine-Kinase-Activation-and-Signallinghttp://www.dnatube.com/video/539/Receptor-Tyrosine-Kinase-Activation-and-Signalling -
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GPCR
n GPCR animation
https://highered.mcgraw-hill.com/sites/0072507470/student_view0/chapter17/animation__membrane-bound_receptors_that_activate_g_proteins.htmlhttps://highered.mcgraw-hill.com/sites/0072507470/student_view0/chapter17/animation__membrane-bound_receptors_that_activate_g_proteins.html -
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31
cell response toEpinephrine- results
in glycogen
breakdown and
prevention of
glycogen synthesisresulting in more
glucose for use by
muscles- FIGHT or
FLIGHT
nG-Protein animation
Ad t f AMP
http://highered.mcgraw-hill.com/sites/0072507470/student_view0/chapter17/animation__second_messenger__camp.htmlhttp://highered.mcgraw-hill.com/sites/0072507470/student_view0/chapter17/animation__second_messenger__camp.htmlhttp://highered.mcgraw-hill.com/sites/0072507470/student_view0/chapter17/animation__second_messenger__camp.htmlhttp://highered.mcgraw-hill.com/sites/0072507470/student_view0/chapter17/animation__second_messenger__camp.html -
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n 1. Signal amplification
n Binding of signal to single receptor can cause the synthesis of
many cAMP that activate PKA, each PKA can phosphorylatemany proteins
n 2. Speed
n In one experiment a substantial amount of cAMP was madewithin 20 seconds after addition of signal
Advantages of cAMP
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Intracellular Receptors
receptors found INSIDE the cell
cytoplasm or inside organelles (ex.aldosterone)
receptors for steroid hormones: estrogen andandrogens
Intracellular receptors
https://highered.mcgraw-hill.com/sites/0072507470/student_view0/chapter17/animation__intracellular_receptor_model.htmlhttps://highered.mcgraw-hill.com/sites/0072507470/student_view0/chapter17/animation__intracellular_receptor_model.html -
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Cross talk between
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Cross-talk between
receptors
The receptor types are capable of activatingeach other via signal transduction pathways.
GPCR can activate receptor tyrosine kinasesand begin the MAP kinase cascade
http://www.cellsignal.com/reference/pathway/MAPK_G_Protein.html
Applications of Concept:
activation of glycine receptor
http://www.cellsignal.com/reference/pathway/MAPK_G_Protein.htmlhttp://www.cellsignal.com/reference/pathway/MAPK_G_Protein.htmlhttp://www.nature.com/principles/content/ne0000/ne0000/ne0000/ne0000/1256387/PLS_AnimSystem_nchembio.552.pdf%23toolbar=0/http://www.nature.com/principles/content/ne0000/ne0000/ne0000/ne0000/1256387/PLS_AnimSystem_nchembio.552.pdf%23toolbar=0/http://www.cellsignal.com/reference/pathway/MAPK_G_Protein.htmlhttp://www.cellsignal.com/reference/pathway/MAPK_G_Protein.html -
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Group work
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Group workn How does the cell communicate? How does distance
determine method? provide an example
n Explain what a ligand is and how it binds to a receptor?
n What types of cell surface receptors are there? How do
they differ? How are they similar?
n What is a kinase? A phosphatase? What role do they play
in cell communication?
n Describe how each receptor type works to mediate a cell
response
n What are second messengers? Why are they used, what
are their advantages?
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Post Lecture Quiz
n module 22 quiz
http://www.nature.com/principles/ebooks/biol1115-1116-general-biology-1-17691792/17694926/4http://www.nature.com/principles/ebooks/biol1115-1116-general-biology-1-17691792/17694926/4