Cell Signaling of Health and Disease

Cell Signaling of Health and Disease - Cell Signaling of...

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Cell Signaling of Health and Disease [NPB 107] Exam One Notes: Lectures 1-6 Quorum sensing: used by decentralized groups to coordinate behavior o Vibrio fisheri produces light when there is a high enough density of vibrio fisheri regulated by transcription from the lux operon that is controlled by an autoinducer molecule. Transcription is initiated when the autoinducer reaches the critical concentration o Vibrio cholerae can communicate with each other through small, diffusible, self-produced molecules, a process called quorum sensing and then it can know when to maximize the ability to cause disease and when to conserve resources. Mating yeast o Haploid cells can mate with haploid cells of the opposite type to form a diploid cell and diploid cells can split into four haploid spores (two a and two alpha) under stressful conditions o Genetics in yeast is powerful and easy because we only need to look at a single cell in order to figure out a reasonably straight forward signaling pathway. We can then use this knowledge of signaling pathway to apply concepts to more complex organisms like mammals Major classes of biological signals o Environmental stimuli: sound, light, temperature, touch, taste, smell; molecules, xenobiotics, toxic substances, other stress factors o Between organisms: pheromones, gamones, sound, sight, touch, taste, smell o Between cells (intercellular): systemic mediators (hormones); local mediators (tissue hormones, cytokines, lipid mediators, neurotransmitters, nitrogen monoxide); cell surface proteins like cell adhesion molecules o Within cells (intracellular): second messengers like cyclic nulceotides, diacyglycerol, inositol phosphates, calcium; interaction domains of proteins Primarily mediated by reversible changes in the activity of cellular proteins achieved through allosteric (change in one place changes another) conformational changes o Within protein molecules: conformational changes Boolean "AND" and NMDA o coincidence detector, with NMDA where NMDA can act as a coincidence detector for glutamate AND depolarization of the cell b/c only occurs when cell is depolarized. The cell is depolarized when AMPA expression occurs because when AMPA receptors are activated the cell is depolarized Five different levels of signaling pathways
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1. Gap Junction: a gap junction directly connects the cytoplasm of two cells allowing communication though letting things like salt, amino acids, vitamins, inorganic ions, and small sugars pass between cells while keeping many large things like proteins, DNA, polysacharides etc separated. The two components where contact occurs are called hemichannels and the opening and closing can be regulated by pH levels to prevent adjacent cell damage i. Strokes- if one area of cells has too much calcium gap junctions begin to close to prevent cell damage ii.
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