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LuisWk7ans(2) - • Ligand binds to inactivate receptor •...

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Bio D103: Cell Biology Bio. Department Tutoring Winter 08: Week 7 Lectures 16-17 2/20/08 Wed. 1-3:00 SH157 1. You will be learning many signaling pathways. It is important not just to simply memorize the pathways but to understand and recognize the basic purpose and principles of signaling. In that case why is signaling needed? The plasma membrane isolates a cell from its environment. Cells require a method to sense their environment. Signaling allows a cell to receive information from its environment and to respond to the  signal. Unicellular organisms use signaling to sense nutrient supply and environmental  conditions. Metazoan organisms use signaling for same reasons, as well as to co-ordinate proper  control of development and homeostasis. Every metazoan organism uses similar types of signaling that evolved from early  primitive multi-cellular organisms. 2. Outline the basic steps of G-protein signal transduction?
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Unformatted text preview: • Ligand binds to inactivate receptor • Active GPCR has conformational change. • GPCR interacts with the alpha subunit of an inactive GDP-bound G protein • Alpha subunit has a conformational change which causes a high affinity for GTP • Conformational change causes GTP-bound active G protein. GTP addition mediates dissociation of alpha subunit form beta and gamma subunits • GTP-bound Alpha subunit regulates target proteins • GTP is hydrolyzed • G-alpha subunit reassembles to make inactive G protein 3. When a cell releases a signal molecule into the environment and a number of cells in the close vicinity respond, this type of signaling is A) typical of hormones. B) autocrine signaling. C) synaptic signaling. D) paracrine signaling. E) endocrine signaling. Autocrine signaling—when a cell releases a signal that acts upon itself Paracrine—acts LOCALLY only. Released in contained manner...
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LuisWk7ans(2) - • Ligand binds to inactivate receptor •...

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