1. During muscle contraction, calcium ions bind to ... A. the actin myofilament.
ID: 3477006 • Letter: 1
Question
1. During muscle contraction, calcium ions bind to ...
A. the actin myofilament.
B. the troponin molecule
C. the sarcoplasmic reticulum.
D. the sarcolemma.
E. the tropomyosin molecule.
2. the bond between the actin and myosin head is broken when ....
A. an ATP molecule binds to the actin molecule.
B. an ATP molecule breaks down the myosin head.
C. ADP and phosphate bind to the myosin head.
D. and ATP molecule binds to the myosin head.
E. an ATP molecule breaks down on the actin molecule.
3. Energy is released when...
A. ADP and phosphate combine to form ATP.
B. ADP is broken down into ATP and phosphate.
C. ATP is broken down into ADP and phosphate.
D. ATP and phosphate combine to form ADP.
E. AMP and two phosphates combine to form ATP.
Explanation / Answer
1. The answer is: B. the troponin molecule
In skeletal muscle contraction, calcium ions bind to troponin molecule which moves tropomyosin from blocking active site on actin, such that myosin head can now bind to actin.
2. The answer is: D. an ATP molecule binds to the myosin head.
When an ATP molecules bind to myosin head, it releases from actin molecule.
3. The answer is: C. ATP is broken down into ADP and phosphate
When this energy is released the myosin head realigns itself to its starting position.
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