exam II study guide

exam II study guide - Lecture Outline 6 Pages 201-217 I...

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Lecture Outline 6 Pages: 201-217 I. External Signals Transformed Cellular Responses (Signal Transduction Pathway) *2 sexes: 1. a- secrets a chemical signal called a factor, which can bind to specific receptor proteins on nearby alpha cells 2. alpha- secrete alpha factor, which binds to receptors on a cells *w/o actually entering the cells, the 2 mating factors cause the cells to grow results in the fusion/mating of 2 cells of opposite types *new cell contains all the genes of both original cells a. Long-distance signaling 1. Hormones (endocrine signaling)- specialized cells release hormone molecules into vessels of the circulatory system, by which they travel to target cells in other parts of the body 2. The signal must be recognized by a specific receptor molecule, & the info it carries must be transduced inside the cell before the cell can be respond. b. Short/Local distances 1. between adjacent cells: gap junctions 2. membrane bound surface molecules (cell-cell or self/non-self recognition) 3. growth factors- compounds that stimulate nearby target cells to grow & multiply 4. paracrine signaling- cells can simultaneously receive/respond to the molecules of growth factor produced by a single cell in their vicinity 5. synaptic signaling- an electrical signal along a nerve cell triggers the secretion of a chemical signal in the form of neurotransmitter molecules (nerve cell-cell signaling) II. Three Stages of Cell Signaling a. Reception: in general 1. Larger protein (receptor protein) embedded in cell membrane or within the cell receives a chemical signal (ex. Ligand) 2. Ligand binding causes larger protein to change conformation 3. This binding can occur at cell surface or internally (within) such as the nuclear envelope 4. A number of important ligands can move through the cell membrane and initiate their responses at some other location in the cell. examples: steroids, thyroid hormones, NO. 5. Note, testosterone is a steroid that slips through the cell membrane and then behaves as a transcription factor 6. Intracellular Receptors- proteins found in the cytoplasm or nucleus of target cells; hydrophobic/small enough to cross the phospholipids interior of the membrane
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*transcription factors- proteins that control which genes are turned on in a particular cell at a particular time b. Membrane Receptors (G-protein-linked) *most water-soluble signal molecules bind to specific sites on receptor proteins embedded in the cells plasma membrane, transmitting info by changing shape or aggregating when a specific ligand binds it 1. G-protein Receptors- a plama membrane receptor that works w/ the help of the G protein (many different receptor configurations) 2. The gross anatomy of a G-protein is highly conserved (similar for all) 3. Very diverse in their functions, extremely widespread *specific signal molecules- cause ligand-gated ion channels in a membrane to open or close, regulating the flow of specific ions
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exam II study guide - Lecture Outline 6 Pages 201-217 I...

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