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Unformatted text preview: Cell signals Signal transduction can coordinate responses to environment (ex. Food, light, gravity) and development (formation of tissues, timing of cell division, direction of cell enlargement, size and shape of organs) These processes occur properly because signals tell them what to do Ligand- something that a signal binds to Control of enzyme activity and gene expression often involve receptors in plasma membrane Receptors are proteins Dimerize- receptors touch to become active (ex. Kinase receptors in plasma membrane come together in the presence of a signal and dimerize to release phosphates) Polar/charged molecules (which cant get through a plasma membrane easily because they are polar and charged) have receptors in the plasma membrane (p.m. receptors) Hydrophobic signals can have cytoplasmic receptors Sodium, insulin, acetylcholine, pressure (non-chemical signal) all affect things on the signal Estrogen, cortisol, light have receptors inside the cell; move easily through plasma membrane After reception, the next step is to transduce the signal Transduction- events between the stimulus and response; signal binds to receptor and then things happen before the cell responds appropriately Different responses will have different transduction steps Some signals involved in transduction steps- Phosphorylation- kinase- adds phosphate; phosphoatase- removes phosphate Voltage change or ion transport across membrane Protein association/dissociation GTP, GTP hydrolysis (G proteins)- like ATP; catalyzed by G proteins Lipid metabolites (IP3: inositol triphosphate; DAG; diacyglycerol)...
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This note was uploaded on 12/08/2010 for the course BIS 2A taught by Professor Grossberg during the Fall '08 term at UC Davis.
- Fall '08