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QUESTION 3 The calcium channel in the SR is considered to be gated

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QUESTION 3

1. The calcium channel in the SR is considered to be gated. That calcium channel is specifically  requiresdoes not requireAChcalciumchemicallyclosesmechanicallyopenssodium and potassiumSR membranet-tubulesvoltage-gated. That means that it  requiresdoes not requireAChcalciumchemicallyclosesmechanicallyopenssodium and potassiumSR membranet-tubulesvoltage when the action potential runs along the  requiresdoes not requireAChcalciumchemicallyclosesmechanicallyopenssodium and potassiumSR membranet-tubulesvoltage. The gating of the channel  requiresdoes not requireAChcalciumchemicallyclosesmechanicallyopenssodium and potassiumSR membranet-tubulesvoltage ATP to occur.Meanwhile, on the postsynaptic membrane of the neuromuscular junction there are also gated channels. These are also called  requiresdoes not requireAChcalciumchemicallyclosesmechanicallyopenssodium and potassiumSR membranet-tubulesvoltage receptors. These channels are considered to be  requiresdoes not requireAChcalciumchemicallyclosesmechanicallyopenssodium and potassiumSR membranet-tubulesvoltage-gated. In order to open, it  requiresdoes not requireAChcalciumchemicallyclosesmechanicallyopenssodium and potassiumSR membranet-tubulesvoltage ATP. When these gated channels are open they allow  requiresdoes not requireAChcalciumchemicallyclosesmechanicallyopenssodium and potassiumSR membranet-tubulesvoltage to pass through them.

   QUESTION 4

   1. Please keep in mind that an answer can be used more than once.In a sarcomere there are both actin and myosin filaments. The  actin filamentmyosin filamentactin-binding sitemyosin-binding siteATP-binding siteATPasetroponinheadtailhinge has tropomyosin associated with it. When a muscle fiber is resting, the tropomyosin blocks the  actin filamentmyosin filamentactin-binding sitemyosin-binding siteATP-binding siteATPasetroponinheadtailhinge on each actin protein. After calcium is available, tropomyosin is tugged out of the way by  actin filamentmyosin filamentactin-binding sitemyosin-binding siteATP-binding siteATPasetroponinheadtailhinge. This enables each myosin  actin filamentmyosin filamentactin-binding sitemyosin-binding siteATP-binding siteATPasetroponinheadtailhinge group to attach to the thin filament with its  actin filamentmyosin filamentactin-binding sitemyosin-binding siteATP-binding siteATPasetroponinheadtailhinge. When the powerstroke occurs, the myosin protein bends at the  actin filamentmyosin filamentactin-binding sitemyosin-binding siteATP-binding siteATPasetroponinheadtailhinge on its neck. The powerstroke pulls on the entire  actin filamentmyosin filamentactin-binding sitemyosin-binding siteATP-binding siteATPasetroponinheadtailhinge so that the Z-lines are pulled inward. In order to do this again, another adenosine triphosphate molecule has to bind to the  actin filamentmyosin filamentactin-binding sitemyosin-binding siteATP-binding siteATPasetroponinheadtailhinge on the  actin filamentmyosin filamentactin-binding sitemyosin-binding siteATP-binding siteATPasetroponinheadtailhinge region of the myosin molecule so that the cross-bridge can disconnect. To become re-energized, the head group has to break down the ATP molecule using its  actin filamentmyosin filamentactin-binding sitemyosin-binding siteATP-binding siteATPasetroponinheadtailhinge function. Throughout this entire time, the  actin filamentmyosin filamentactin-binding sitemyosin-binding siteATP-binding siteATPasetroponinheadtailhinge region of the myosin molecules are not doing anything but remaining stuck within the  actin filamentmyosin filamentactin-binding sitemyosin-binding siteATP-binding siteATPasetroponinheadtailhinge to hold all the myosin molecules together.

   QUESTION 6

   1. Examine the steps below and put them in the correct order. - 1. 2. 3. 4. 5. 6. 7. 8. 9. 10.  Calcium unbinds from the troponin  - 1. 2. 3. 4. 5. 6. 7. 8. 9. 10.  An action potential is generated in the muscle fiber  - 1. 2. 3. 4. 5. 6. 7. 8. 9. 10.  Power stroke carried out by myosin heads  - 1. 2. 3. 4. 5. 6. 7. 8. 9. 10.  Calcium ions bind to troponin allowing formation of cross bridges  - 1. 2. 3. 4. 5. 6. 7. 8. 9. 10.  DHP receptor changing shape causes calcium ion to be released from the sarcoplasmic reticulum into the cytosol.  - 1. 2. 3. 4. 5. 6. 7. 8. 9. 10.  ACh levels rise in the neuromuscular junction  - 1. 2. 3. 4. 5. 6. 7. 8. 9. 10.  Myosin heads release and elastic filaments pull filaments back to relaxed position.  - 1. 2. 3. 4. 5. 6. 7. 8. 9. 10.  Na+ enters into the muscle fiber through ACh receptor channels.  - 1. 2. 3. 4. 5. 6. 7. 8. 9. 10.  Calcium ions are pumped by active transport into sarcoplasmic reticulum  - 1. 2. 3. 4. 5. 6. 7. 8. 9. 10.  Action potential travels along sarcolemma and t-tubules causing the DHP receptor to change shape