What protein is arranged along the length of actin filaments and is involved in regulation of skeletal muscle contraction?
1. | Troponin | 2. | Calmodulin |
3. | Tropomyosin | 4. | Light meromyosin |
Which of the following masks the active sites on actin when a skeletal muscle is relaxed?
1. | Tropomyosin | 2. | Troponin |
3. | Calmodulin | 4. | Ubiquitin |
1. | shortening of both actin and myosin myofilaments |
2. | shortening of actin and lengthening of myosin myofilaments |
3. | the sliding of the thin filaments over the thick filaments |
4. | the sliding of the thick filaments over the thin filaments |
1. | a motor neuron and all of the skeletal muscle fibers innervated by the neuron's axon terminals. |
2. | all motor neurons and all of the skeletal muscle fibers innervated by them in a muscle. |
3. | a motor neuron and one skeletal muscle fiber innervated by the neuron. |
4. | a motor neuron and a sensory neuron. |
Statement I: | The junction between a motor neuron and the sarcolemma of the muscle fibre is called the neuromuscular junction. |
Statement II: | A neural signal reaching the neuromuscular junction releases a neurotransmitter, Acetyl choline, which generates an action potential in the sarcolemma. |
The neurotransmitter released by the motor neurons at the neuromuscular junction is:
1. | Acetylcholine | 2. | Noradrenaline |
3. | GABA | 4. | Adrenaline |
1. | binds to the actin and myosin and makes them work together. |
2. | breaks apart ATP to ADP and P. |
3. | removes the tropomyosin block. |
4. | causes the release of acetylcholine. |
The critical event for the contraction of striated muscles would be that calcium ions:
1. | are released from troponin C |
2. | bind to tropomyosin |
3. | bind to troponin |
4. | are taken up by the sarcoplasmic reticulum |
1. | the myosin head binds to the exposed active sites on actin utilising the energy from ATP hydrolysis |
2. | the myosin head binds to the exposed active sites on actin and then the ATP binds to its site on myosin head |
3. | the actin binds to the exposed active sites on myosin head utilising the energy from ATP hydrolysis |
4. | the actin binds to the exposed active sites on myosin head and then the ATP binds to its site on actin |
During muscle contraction, when the myosin head releases ADP and iP it:
1. forms cross bridge with actin
2. pulls actin towards M-line
3. goes back to its relaxed state
4. gets detached from the cross bridge