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Explore the intricate processes of cell communication and response mechanisms in organisms, including yeast, bacteria, and animals. Learn about receptors, signal transduction pathways, and the amplification of cellular responses. Examine examples of hormone-induced cellular responses and the role of second messengers like cAMP and Ca2+. Understand the specificity of cell signaling and the involvement of scaffolding proteins.
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Figure 11.1 Communication between mating yeast cells • Cell Communication • Between separate organisms • Between cells within an organism
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
Three Stages of Cell Signaling • Reception: detection of signal • Transduction: signal converted to form that yields cellular response • Response Earl Sutherland
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 11.8 The structure and function of a tyrosine-kinase 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.
Examples of Hormone-induced Cellular Responses Mediated by cAMP
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
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