MCB 32 Lecture 7 - Molecular Cell Biology 32 Professor...

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Molecular Cell Biology 32 Professor Terry Machen 9/16/10 Lecture 7 ASUC Lecture Notes Online is the only authorized note-taking service at UC Berkeley. Do not share, copy, or illegally distribute (electronically or otherwise) these notes. Our student-run program depends on your individual subscription for its continued existence. These notes are copyrighted by the University of California and are for your personal use only. D O N O T C O P Y Sharing or copying these notes is illegal and could end note taking for this course. ANNOUNCEMENTS Review session next Thursday from 6–8 p.m. There will be a review handout. LECTURE Question from last lecture about what the van’t Hoff factor is Osmotic pressure is proportional to the amount of dissolved molecules. Osmotic pressure = ʌ ȆRVP 57 FRQF R = gas constant .0821 J/mol K ? Different depending on units T = temperature For ions: ȆRVP L57 FRQF i = van hoff factor = # ions dissolved NaCl i = 2 CaCl2 i = 3 Synapses Inactivation of neurotransmitter Transmitter activation of postsynaptic receptor Synaptic integration between different cells EPSP’s and IPSP’s in postsynaptic nerve CNS Anatomy Somatic sensory pathway Somatic motor pathway Reflexes: An action potential is propagated and the signal causes the release of neurotransmitter vesicles from the presynaptic nerve to the postsynaptic nerve where it binds to a receptor. The neurotransmitters that move across the synapse must be inactivated. The inactivation process is out of sync of what you normally might think. The synaptic chemical is released and, if it remains, changes can lead to many consequences. However, we want the signal to turn on quick and turn off quick. The picture below shows a presynaptic and postsynaptic nerve which are bound by lipid bilayers. Neurotransmitters are contained in sacs, i.e. acetylcholone. Acetylcholineesterase breaks down acetylcholone into actetate and choline, and the enzyme cleaves it into these 2 molecules. Figure 1. Electron micrograph of 1 myelinated nerve boutan (has synaptic vesicles with acetylcholine)
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MCB 32 ASUC Lecture Notes Online: Approved by the UC Board of Regents 9/16/10 D O N O T C O P Y Sharing or copying these notes is illegal and could end note taking for this course. 2 Anatomy emphasizes the constraints present in synapses. The cleft is so small (less than 1 micron) so that the neurotransmitters can diffuse quickly over a short distance. Acetylcholinesterase is contained in the membrane, adjacent to acetylcholine receptor (nicotinic). Nicotine can activate the receptor. Summary: Acetylcholine is cleaved by Ach esterase to acetate and choline. They are recycled into the presynaptic nerve and re-synthesized into acetylcholine, packaged into vesicle and then it repeats. If acetylcholine esterase is blocked, there is a buildup of ACh in this space and leads to persistent activation. It will happen all across body and can be deadly. An example is the sarin gas attack in a Tokyo subway some years ago. Someone released
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MCB 32 Lecture 7 - Molecular Cell Biology 32 Professor...

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