Science Homework Help

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