bio quiz - 1 Outline molecular mechanism of memory in...

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1. Outline molecular mechanism of memory in Aplesia . In the vertebrate brain, a form of learning, called long-term potentiation involves an increase in the strength of synaptic transmission that occurs when presynaptic neurons produce a brief, high-frequency series of action potentials. Because LTP can last for days or weeks, it may be a fundamental process by which memories are stored or learning takes place. Sensitization involves interneurons that make synapses on the synaptic terminals of the siphon sensory neurons. When the tail is shocked, the interneurons release seratonin, which activates a signal transduction passageway that closes K + channels in the synaptic terminals of the siphon sensory neurons. As a result, action potentials in the siphon sensory neurons produce a prolonged depolarization of the terminals. That allows more Ca 2+ to diffuse into the terminals, which causes the terminals to release more of their excitatory neurotransmitter onto the gill motor neurons. In response, the motor neurons generate action potentials at a higher frequency, producing a more forceful gill withdrawl. 2. Outline events at a typical synapse A synapse is the site of communication between a synaptic terminal and another cell. Most synapses are chemical synapses, which involve the release of a chemical neurotransmitter by the presynaptic neuron. The presynaptic neuron synthesizes the neurotransmitter and packages it in synaptic vesicles, which are stored in the neuron’s synaptic terminals. When an action potential reaches a synaptic terminal, it depolarizes the terminal membrane, opening voltage -gated calcium channels in the membrane. Calcium ions (Ca 2+ ) then diffuse into the terminal, and the rise in Ca 2+ concentration in the terminal causes some of the synaptic vesicles to fuse with the terminal membrane, releasing the neurotransmitter by exocytosis. The neurotransmitter then diffuses across the synaptic cleft, which separates the presynaptic neuron from the postsynaptic cell. 3 . Diagram muscle structure and outline how it works. See page 1066, Figure 49.27 for the diagram The action of a muscle is always to contract; muscles can extend only passively. Therefore, the ability to move parts of the body in opposite directions requires that muscles be attached to the skeleton in antagonistic pairs, each member of the pair working against the other. We flex an arm by contracting the biceps, with the hinge joint of the elbow acting as the fulcrum of a lever. To extend the arm, we relax the biceps while the triceps on the opposite side contracts. 1066-1077 goes into specific detail on different muscle contraction, which isn’t the question, but it’s there if you want to read it. 4. List major characters and plot outline in
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bio quiz - 1 Outline molecular mechanism of memory in...

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