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Membrane_receptor_systems - NOT ON MIDTERM 1 has to do...

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Topic 5 – Cell-to-cell signalling Reading Chapter 8 Objectives Cell communication and signalling systems BIO 1140 – SLIDE 1 Signals recognized by cell- surface receptors Ligand-gated channels Receptor tyrosine kinases G protein-coupled receptors Lipid-soluble signals & intracellular receptors http://www.cellsignal.com/reference/pathway/ Types of cell communication Direct – gap junctions and plasmodesmata Contact – recognition and adhesion e.g. cadherins, integrins Chemical messengers Cell A Cell communication – the broader context BIO 1140 – SLIDE 2 Cell B pore connexin connexon small molecule http://www.ncbi.nlm.nih.gov/books/NBK9874/ Fig. 3.2, Moyes & Schulte 2008 http://www.ncbi.nlm.nih.gov/books/NBK9834/ cadherins Types of chemical messengers Hormones Paracrine messengers Neurotransmitters and neurohormones BIO 1140 – SLIDE 3 Fig. 16-3, Alberts et al. 2010 - NOT ON MIDTERM 1 - has to do mostly with multicellular organisms - greatest need for cells to communicate with each other - can be very complex - despite this, basic principles exist for signalling - two broad signalling - how they enter cell differs - cell to cell communication occurs in a variet of ways direct - ex. coordinating heart beat with gap junctions contact -cell surface proteins that either bind to each other or to other molecules chemical messengers - many types - hormones - chemical messengers synthesized by specialized cells --- transported by vesicles to distant destination - neurotransmitters - in neurons - paracrine - secreted by a cell that act on other cells -- local mediator is a paracrine messenger Pop quiz - distinguish between Ras and G-protein -- G protein - made up of three subunits while Ras is a type of G-protein that is only one subunit. -- both hydrolyze GTP -- Ras involved in cell growth and differentiation - often have growth factors - receptor kinase... -- G protein - heterotrimeric proteins activated by G-protein coupled receptors - adenylyl cyclase and why does it matter? -- enzyme that produces GNP activated by G-protein - adenylyl cyclase is how we get cAMP - everyone wants that - caffeine (phosphodiesterase inhibitor) be predicted to have on glucose release from liver cells? -- increase glucose release from liver cells by increasing glycogen breakdown - phosphodiesterase stops formation of cAMP - this prevents phosphodiesterase from binding- prolonged effect of cAMP
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The “fight or flight” response What is this response? How is it activated? BIO 1140 – SLIDE 4 Steps in a signalling system Signalling molecule (first messenger) Reception Ligand-binding site Only cells with receptor respond to signal Membrane, cytosolic or nuclear BIO 1140 – SLIDE 5 Transduction Conversion of signal to cellular response Cellular response Changes in gene expression Changes in protein activity Responses can be cell type-specific Termination Fig. 8.2 Steps in a signalling system Signalling molecule (first messenger) Reception Ligand-binding site
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