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Unformatted text preview: Biological Science I Tuesdays and Thursdays 8:00-9:15, HCB 102 Mondays 5:15-6:15, KIN 1024 23 February 2011 Lecture 15 CELL COMMUNICATION By the end of this lecture you should be able to: Describe the nature of a ligand-receptor interaction and state how such interactions initiate a signal- transduction system Compare and contrast G protein-coupled receptors, tyrosine kinase receptors, and ligand-gated ion channels List two advantages of a multistep pathway in the transduction stage of cell signaling Explain how an original signal molecule can produce a cellular response when it may not even enter the target cell Define the term second messenger; briefly describe the role of these molecules in signaling pathways Explain why different types of cells may respond differently to the same signal molecule Describe the role of apoptosis in normal development and degenerative disease in vertebrates 1. The Cellular Internet a. Cell-to-cell communication is essential for multicellular organisms b. Biologists have discovered some universal mechanisms of cellular regulation c. The combined effects of multiple signals determine cell response d. For example, the dilation of blood vessels is controlled by multiple molecules Concept 11.1: External signals are converted to responses within the cell 2. Evolution of Cell Signaling a. A signal transduction pathway is a series of steps by which a signal on a cells surface is converted into a specific cellular response b. Signal transduction pathways convert signals on a cells surface into cellular responses c. Pathway similarities suggest that ancestral signaling molecules evolved in prokaryotes and were modified later in eukaryotes d. The concentration of signaling molecules allows bacteria to detect population density 3. Local and Long-Distance Signaling a. Cells in a multicellular organism communicate by chemical messengers b. Animal and plant cells have cell junctions that directly connect the cytoplasm of adjacent cells c. In local signaling, animal cells may communicate by direct contact, or cell-cell recognition d. In many other cases, animal cells communicate using local regulators, messenger molecules that travel only short distances e. In long-distance signaling, plants and animals use chemicals called hormones 4. The Three Stages of Cell Signaling: A Preview a. Earl W. Sutherland discovered how the hormone epinephrine acts on cells b. Sutherland suggested that cells receiving signals went through three processes: b.i. Reception 1 Biological Science I Tuesdays and Thursdays 8:00-9:15, HCB 102 Mondays 5:15-6:15, KIN 1024 23 February 2011 Lecture 15 b.ii. Transduction b.iii. Response 2 Biological Science I...
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- Spring '08