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Cell Physiology Slide 2 Exit Home BASIM ZWAIN LECTURE NOTES BASIM ZWAIN LECTURE NOTES Slide 3 Slide 4 Slide 5 Slide 6 Slide 7 Slide 8 Slide 9 Slide 10 Slide 11 Slide 12 Slide 13 Slide 14 Slide 15 Slide 16 Slide 17 Slide 18 Slide 19 Slide 20 Slide 21 Slide 22 Slide 23 Exit Home BASIM ZWAIN LECTURE NOTES BASIM ZWAIN LECTURE NOTES Cell Physiology Plasma membrane Slide 24 Slide 25 Slide 26 Slide 27 Slide 28 Slide 29 Slide 30 Slide 31 Slide 32 Slide 33 Slide 34 Slide 35 Slide 36 Slide 37 Exit Home BASIM ZWAIN LECTURE NOTES BASIM ZWAIN LECTURE NOTES Cell Physiology Transport processes Slide 38 Passive Processes Simple diffusion Facilitated diffusion Osmosis Filtration Exit Home BASIM ZWAIN LECTURE NOTES BASIM ZWAIN LECTURE NOTES Slide 39 Exit Home BASIM ZWAIN LECTURE NOTES BASIM ZWAIN LECTURE NOTES Cell Physiology Plasma membrane Active Processes Active transport (uniport, symport and antiport) -Primary active transport -Secondary active transport Slide 40 Exit Home BASIM ZWAIN LECTURE NOTES BASIM ZWAIN LECTURE NOTES Slide 41 Exit Home BASIM ZWAIN LECTURE NOTES BASIM ZWAIN LECTURE NOTES Slide 42 Exit Home BASIM ZWAIN LECTURE NOTES BASIM ZWAIN LECTURE NOTES Cell Physiology Plasma membrane Active Processes Bulk (vesicular) transport Endocytosis (Pinocytosis, phagocytosis and receptor mediated endocytosis) Exocytosis (and transcytosis) Slide 43 Exit Home BASIM ZWAIN LECTURE NOTES BASIM ZWAIN LECTURE NOTES Slide 44 Exit Home BASIM ZWAIN LECTURE NOTES BASIM ZWAIN LECTURE NOTES Cell Physiology Plasma membrane Types of junctions Tight junctions Desmosomes (anchoring junctions) Gap (or communicating) junctions Slide 45 Exit Home BASIM ZWAIN LECTURE NOTES BASIM ZWAIN LECTURE NOTES Slide 46 Intercellular Communication Slide 47 47 Communication between cells requires: ligand: the signaling molecule receptor protein: the molecule to which the receptor binds -may be on the plasma membrane or within the cell Intercellular Communication Slide 48 48 Slide 49 49 There are four basic mechanisms for cellular communication: 1. direct contact 2. paracrine signaling 3. endocrine signaling 4. synaptic signaling Intercellular Communication Slide 50 50 Direct contact molecules on the surface of one cell are recognized by receptors on the adjacent cell Intercellular Communication Slide 51 51 Paracrine signaling signal released from a cell has an effect on neighboring cells Intercellular Communication Slide 52 52 Endocrine signaling hormones released from a cell affect other cells throughout the body Intercellular Communication Slide 53 53 Synaptic signaling nerve cells release the signal (neurotransmitter) which binds to receptors on nearby cells Intercellular Communication Slide 54 54 When a ligand binds to a receptor protein, the cell has a response. signal transduction: the events within the cell that occur in response to a signal Different cell types can respond differently to the same signal. Intercellular Communication Slide 55 55 A cells response to a signal often involves activating or inactivating proteins. Phosphorylation is a common way to change the activity of a protein. protein kinase an enzyme that adds a phosphate to a protein phosphatase an enzyme that removes a phosphate from a protein Intercellular Communication Slide 56 56 Slide 57 57 Receptor Types Receptors can be defined by their location. intracellular receptor located within the cell cell surface receptor or membrane receptor located on the plasma membrane to bind a ligand outside the cell Slide 58 58 Receptor Types There are 3 subclasses of membrane receptors: 1. channel linked receptors ion channel that opens in response to a ligand 2. enzymatic receptors receptor is an enzyme that is activated by the ligand 3. G protein-coupled receptor a G- protein (bound to GTP) assists in transmitting the signal Slide 59 59 Slide 60 60 Intracellular Receptors steroid hormones -have a nonpolar, lipid-soluble structure -can cross the plasma membrane to a steroid receptor -usually affect regulation of gene expression An inhibitor blocks the receptor from binding to DNA until the hormone is present. Slide 61 61 Intracellular Receptors A steroid receptor has 3 functional domains: 1. hormone-binding domain 2. DNA binding domain 3. domain that interacts with coactivators to affect gene expression Slide 62 62 Slide 63 63 Receptor Kinases receptor tyrosine kinases -membrane receptor -when bound by a ligand, the receptor is activated by dimerization and autophosphorylation -activated receptor adds a phosphate to tyrosine on a response protein -an example is the insulin receptor Slide 64 64 Slide 65 65 Slide 66 66 Receptor Kinases kinase cascade a series of protein kinases that phosphorylate each other in succession -amplifies the signal because a few signal molecules can elicit a large cell response mitogen-activated protein (MAP) kinases are activated by kinase cascades Slide 67 67 Slide 68 68 Slide 69 69 G-Protein Coupled Receptors G-protein protein bound to GTP G-protein-coupled receptor (GPCRs) receptors bound to G proteins -G-protein is a switch turned on by the receptor -G-protein then activates an effector protein (usually an enzyme) Slide 70 70 Slide 71 71 G-Protein Coupled Receptors Once activated, the effector protein produces a second messenger. -second messenger generates the cellular response to the original signal For example one common effector protein is adenylyl cyclase which produces cAMP as a second messenger. Other second messengers: inositol phosphates, calcium ions (Ca 2+ ) Slide 72 72 Slide 73 73 Cell-to-Cell Interactions Cells can identify each other by cell surface markers. -glycolipids are commonly used as tissue- specific markers -major histocompatibility complex (MHC) proteins are used by cells to distinguish self from non-self Slide 74 74 Cell-to-Cell Interactions Cells within a tissue are connected to each other by cell junctions 1. tight junctions create sheets of cells 2. anchoring junctions connect the cytoskeletons of adjacent cells 3. communicating junctions permit small molecules to pass between cells a. gap junctions in animal cells b. plasmodesmata in plant cells Slide 75 75 Slide 76 76 Slide 77 77 Slide 78 Cell Physiology Exit Home BASIM ZWAIN LECTURE NOTES BASIM ZWAIN LECTURE NOTES