The function of the protein dystrophin a. is to enable calcium to be taken back

Question

The function of the protein dystrophin a. is to enable calcium to be taken back up into the sarcoplasmic reticulum at the end of contraction b. is to link the protein myosin to the Z- disc c. it is a receptor protein on the surface of the sarcolemma for acetylchline d. it links the actin proteins to integral proteins of the sarcolemma e. is to bind to calcium and stimulate the tropomyosin protein to slide on the actin protein ATP is used in the process of muscle contraction for which functions listed below? a. detachment of myosin heads from actin b. attachment of myosin heads to actin c. active transport of calcium back into the sarcoplasmic reticulum by calcium pumps d. generation of the action potential along the sarcoplasm e. both a and c Which of the following regions of the sarcomere is extensible? a. the I -band b. the A-band c. the M-line d. the Z-disc e. both a and b Terminal cisterna merge into which of the following structures within the muscle cel

Explanation / Answer

41.d.The Dystrophin protein provides a structural link between the muscle cytoskeleton and extracellular matrix to maintain muscle integrity. Recently, Dystrophin has also been found to act as a scaffold for several signaling molecules, but the roles ofdystrophin-mediated signaling pathways remain unknown.

42.e.ATP then binds to myosin, moving the myosin to its high-energy state, releasing the myosin head from the actin active site. ATP can then attach to myosin, which allows the cross-bridge cycle to start again; further muscle contraction can occur.

43.a.Upon muscle contraction, the A-bands do not change their length (1.85 micrometer in mammalian skeletal muscle),whereas the I-bands and the H-zone shorten. This causes the Z lines to come closer together.

44.e.The Calcium Release Unit of muscle consists of the terminal cisternae of the sarcoplasmic reticulum and its adjacent transverse or T-tubule that is the invaginated part of the surface membrane.

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