Cell Communication

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reactions that activale the target molecules 3. Cellular Response A change in metabolism, a change in charge across the membrane, & change in gene expression I Forms of Signaling Cells Sending the signal synthesize & secrete ligands, that will be recieved by the receiving cell at a receptor protein. Ligands can be proteins or steriods, where some bind to nearby. cells or to themselves. 4 Categories of chemical signaling: 1. Direct Contact Signaling-Signaling across gap junctions. 2. Autocrine Signaling-Self signaling 3. Parachne signaling- Nearby Signaling 4. Endocrine Signaling-Long distance Signaling. Direct Contact Signaling Gap junctions in animals & plasmodesmata in plants are connections between the plasma membranes of neighboring cells. • Connections filled w/ cytoplasm Signaling cell Gap 104 which allows diffusion of small ligands tions into neighboring cells •Molecular specificity of gap junctions. & Plasmodesmata ensures that the cells remain independent while allowing signals to be transmitted easily & quickly! Self = Autocrine Signaling] کھا ا ا ا ا ای کرکر کے cell targets itself Target cell connexions cell wall -cytoplasm -Vacuole LPlasmodesma Produced when signaling cell + target cell are the same/similar cell •Occurs during early development of an organism to ensure cells develop into correct tissues. Regulates: 1. Pain sensation. 2. Inflammatory Responses 3. Programmed cell death 4. cellorar differentiation during development Paracrine Signaling Signals that act locally between cells that are close together Paracrine Signals: 1. Diffusion through extracellular matrix 2. Quick responses that last a short time. 3. ligands degraded by enzymes or removed by neighboring cells Synaptic Signaling - the transfer of signals across synapses between nerve • When these impulses reach the end. of the axon, the signal continues on to a dendrite of the next cell by the release of chemical ligands called neurotransmitters •Signals within the nerve cells are grown by Past moving eletrical potses sending cell 2005 Neurotransmitter-chemical ligand that Cames a signal from one nerve cell to the next. Signaling cell Signaling cell bloodstream Target cell Endocrine Signaling orginated from Long-distance signals sent from distant cells (endocume cells Target cell neurotransmitter MEHM-receptor TReceiving cell •Slow response but long-lasting effect •Hormones released. Hormones travel large distances. between endocrine cells & their target. cells via bloodstream. Hormones get diluted & are present in low Concentrations 77777777 • Types of Ligands + Receptors. Types of Receptors Receptors are protein molecules in the target cell or on its surface that bind ligands 2 Types: Internal receptors & cell-surface receptors. intracellular or (hydrophobic) cytoplasmic Internal Receptors -Bind to ligands that pass through. Signaling Extracellular fluid SA Plasma membrane cytoplasm Intraceptor- Transmembrane Receptor Nucleus the plasma membrane MNM DNA •Located in cytoplasm • Bind to proteins that act as regulators of MRNA Synethsis to mediate gene expression. •Ligand binds to internal receptor, which exposes DNA-binding site on protein •Ligand-receptor complex moves to nucleus, then binds to chromosomal DNA GInitiate transcription wmil you'll awasilis of quera glogy anh Cell-Surface Receptors - Plasma membrane integral proterns that bind to a ligand outside the cell. • Transmits signal from outside of cell to inside ligand doesn't enter ↳ Signal Transduction 4. Subclasses of Receptors: Cell-Surface Channels →1. Ion channel linked receptors -open in response to ligand Protem 2. Enzymatic Receptors - Enzyme activated by ligand 3.G₁ Protein-linked (coupled) Receptor - Assits transmitting the signal GTP $4. Tyrosine kinase Receptors - Mediate cell to cell communication bound to Ilon channel-linked receptors - Bind a ligand + open a NOWMAN 2269 MAN tuo nediskanale 240 2 channel through membrane that allows. specific ions to pass through.. •Membrane spanning region. •Hydrophilic inside allows passage. of water & iono لسله الجن • Change in protein's structure allows other rons to pass through •Transfer phosphate group to tyrosine moteates. • Signating molecules loond to extracelular domain of 2 RTK. • Receptors bind together. •Phosphates added to tyrosine on intracelular domain of receptors. Ballery velg N MAHMOUR WIS Enzyme-linked Recepfors- intracellular domams that are w/ hydrophsoic an enzyme. •When ligand binds to extracellular domain, signal transferred through mumbovane, activating enzyme. Tyrosme kinase Receptor (RTK). kinase-enzyme that transfers phosphate from ATP to another protein. 8 y & vomit you 003 are c ap G Protein- linked Receptors -Bind ligand & activate membrane Protein called "G-Protein". G-Proten-Potem bound to GTP & Protem-coupled receptor - recepiter bound to fr Proten. Hedve Land GTP GOP socia Active upied of Myys Hormonesho ✪ How Four poke orvertoonvertoont 7. •fitp on active "d" is hydrolyzed to GDP. Encon •By suomit deactivated •Subunits gather •Inactive G-Protem bind to new Site on receptor • change in shape activates G- Protend paten • Releases GIDP, picks up GTTP •Subunits; a + By Steroid Hormones- Small hydrophobic ligands can diffuse to form inactive G-Protein way po baveus ferens 201 [relating vist – Juki Sharq Steroids are cholesterol-based lipids made of hydrocarbon skeletons w/ different fonctioner groups •Non polar, lipid-soluble structure through the membrane & interact w/ receptors inside the cell. intracellular receptors Lon Peptide Hormones - Polar, water-soluble ligands. Can't pass with a through membrane unaided. •Bind to cell-surface receptors. z60/q/85 Transduction A cell's response to a signal often involves activating or hadivating proteins. Phosphorylation is common way to change the activity of protein. Protein kinase-activation Phosphatase-Enzyme romoves phosphate from protem (deactivation) Kinase cascade -series of protein kinases that phosphorylate. each other in succession -1-0-1-0-1-) 201-B-0 MAP kinases - Activated by kinase cascades Amplification - Results b/c a few signal molecules elicit large cell response Adrenaline Rush sale Epinephrine is released & liberates gweose from glycogen •When epinephrine binds to receptor on muscle cell → triggers signal. transduction cascade Second messenger molecule called cyclic AMP CAMP is used •Cascade Heads to phosphorylation of 2 metabolic enzymes Phosphorylation cascade-Sequence of signaling pathway events. of where I enzyme phosphorylates another. Second Messengers-molecules that relay signals recieved at receptors on cell surface to target molecules in cytosol or nucleus. •Amplify the Strength of signal. N 11 MAIN