[cs_content][cs_section parallax=”false” separator_top_type=”none” separator_top_height=”50px” separator_top_angle_point=”50″ separator_bottom_type=”none” separator_bottom_height=”50px” separator_bottom_angle_point=”50″ style=”margin: 0px;padding: 45px 0px;”][cs_row inner_container=”true” marginless_columns=”false” style=”margin: 0px auto;padding: 0px;”][cs_column fade=”false” fade_animation=”in” fade_animation_offset=”45px” fade_duration=”750″ type=”1/1″ style=”padding: 0px;”][cs_text]The Biochemistry of Movement > 9.7.5. Muscle cells cause movement by contraction along their length > Muscle Cell Contractions >[/cs_text][cs_text style=”color: #800000;font-family: “Oxygen”,sans-serif;”]Identify the cause of the muscle cell contraction as the release of calcium ions after a nerve impulse activates the muscle cell membrane[/cs_text][cs_text]
- “Sliding filament theory”
- Ca2+ ions interact with tropomyosin and troponin, exposing the active sites on the actin filament and allowing the myosin head to bind there.
- This allows myosin to catalyse the hydrolysis of ATP, resulting in the energy release, which causes the myosin head to move into a higher energy state.
- The higher energy state permits the head to bind to an active site further along the actin/tropomyosin/troponin strand. This leads to the release of phosphate group and eventually ADP.
- When the nerve impulse ceases, the myosin head resumes its normal resting position.
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