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Figure 11.0 Yeast Figure 11.1 Communication between mating yeast cells Cell Communication •Between separate organisms •Between cells within an organism Figure 11.2 Communication among bacteria Figure 11.3 Local and long-distance cell communication in animals Communicating cells can be close together or far apart. Paracrine Signaling •Histamine released by mast cells. •Inflammation of nearby tissue •Increased secretion of stomach acid Figure 11.4 Communication by direct contact between cells Three Stages of Cell Signaling 1. Reception: detection of signal 2. Transduction: signal converted to form that yields cellular response 3. Response Earl Sutherland Figure 11.5 Overview of cell signaling (Layer 1) Figure 11.5 Overview of cell signaling (Layer 2) Figure 11.5 Overview of cell signaling (Layer 3) Signal Reception • Receptors – – – – Membrane protein On surface of cell Specific Ligand binds receptor causing a change in conformation – Signal transduction pathway initiated • Types of membrane receptors – G-Protein Linked Receptors – Tyrosine kinase receptors – Ion-channel receptors Figure 11.6 The structure of a G-protein-linked receptor Figure 11.7 The functioning of a Gprotein-linked receptor Figure 11.8 The structure and function of a tyrosine-kinase receptor Figure 11.9 A ligand-gated ionchannel receptor Figure 11.10 Steroid hormone interacting with an intracellular receptor Signal Transduction Pathways • Process of relaying signal to produce response. • Often several steps/processes • Amplification • Involves second messengers – Cyclic AMP (cAMP), Ca2+ • Protein Kinase: Enzyme that transfers phosphate from ATP to a protein • Protein Phosphatase: enzyme that removes phosphate from a protein. Figure 11.11 A phosphorylation cascade Figure 11.12 Cyclic AMP Figure 11.13 cAMP as a second messenger Examples of Hormone-induced Cellular Responses Mediated by cAMP Target Tissue Thyroid gland Muscle Heart Hormone TSH Adrenaline Adrenaline Liver Glucagon Major Response TH synthesis/secretion Glycogen breakdown Increase heart rate/force of contract Glycogen breakdown Figure 11.14 The maintenance of calcium ion concentrations in an animal cell Figure 11.15 Calcium and inositol triphosphate in signaling pathways (Layer 1) Figure 11.15 Calcium and inositol triphosphate in signaling pathways (Layer 2) Figure 11.15 Calcium and inositol triphosphate in signaling pathways (Layer 3) Some Cellular Responses Mediated by G-Protein-linked Receptors Coupled to Inositol Phospholipid Signaling Pathway Target Tissue Liver Signaling Molecule Vasopressin Pancreas Acetylcholine Smooth Muscle Acetylcholine Mast cells Antigen Major Response Glycogen breakdown Amylase secretion Contraction Histamine secretion Figure 11.16 Cytoplasmic response to a signal: the stimulation of glycogen breakdown by epinephrine Figure 11.17 Nuclear response to a signal: the activation of a specific gene by a growth factor Amplification of Signal Response Figure 11.18 The specificity of cell signaling Figure 11.19 A scaffolding protein