11Communication11Sp

11Communication11Sp - Biology 6B 11 Cell Communication...

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1 11 & 48: Cell Communication Modes of communication Reception, transduction Nerve signals Yeast cell courtship Mating type is communicated by chemical signals. All cells communicate Bacterial cells communicating to form protective spores. Myxococcus xanthus All cells communicate regulates enzyme activity, gene All cells communicate Cells can communicate over long or short distances. Modes of Cell Communication Diffusible ligands (hormones) Reception, transduction Receptors Second messengers Signaling cascades Cell contact signaling Nerve signals Hormones are secreted into the bloodstream by endocrine organs. They have specific pathways; cells can have different responses to the same hormone. Endocrine signaling Biology 6B 11 Cell Communication Brian McCauley Spring 2011
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2 Polar molecules (such as protein hormones) act on cell-surface receptors. Cell surface receptors G-protein-coupled receptors: A class of receptors for polar molecules. Their ligands include hormones, neurotransmitters, smells, light (opsins), etc. Cell surface receptors G-protein-coupled receptor families G-protein-coupled receptors: All the G-protein- coupled receptors are homologous -- they’re descended from the same ancestral gene. GPCR evolution: paralogy Cell surface receptors act via second messengers. Signal Transduction ATP cyclic AMP AMP cAMP, a second messenger Biology 6B 11 Cell Communication Brian McCauley Spring 2011
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2nd messengers may initiate phosphorylation cascades. Signal Transduction Cascades amplify signals Different cell types may respond differently to the same hormone. Protein hormone response Protein hormones often regulate enzyme activity… and sometimes they regulate gene expression. Steroid hormone signaling Steroid hormones are nonpolar; diffuse across membranes, bind to cytosolic receptors. Steroid + receptor acts as transcription factor. Steroid hormones alter
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11Communication11Sp - Biology 6B 11 Cell Communication...

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