BIOL 103 Lecture Notes - Lecture 6: Cyclic Adenosine Monophosphate, Second Messenger System, Cell Membrane
11 Mar 2014
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Document Summary
Amines and proteins/peptide hormones generally share similar chem. properties and actions; steroid hormones act differently: amines. Derived from a. acid tyrosine ((nor)epinephrine) or tryptophan (melatonin) Target cell receptor on plasma membrane (except thyroid glands) Steroid hormones bound to large, soluble proteins in the blood that act as carriers. Acts in cell cytosol or nucleus; stimulates gene transcription. Ligand binds to a receptor protein on the plasma membrane. Hormones diffuse from the blood into the interstitial fluid, binding to a specific receptor proteins on the cell surface. Only cells w/ the proper receptors on their surfaces can respond to the hormone. ->hormone activates only specific cells in the body. Signal transduction can be rapid and involve enzymes. Also leads to changes in cellular activities that occur more slowly. ->usually requires activation/inhibition of various genes in the nucleus. Isoforms: different receptors that can recognize the same hormone. ->from different genes or alternative splicing of genes.
