Please explain why D is the correct answer 4 pts. 6. Which one of the following
ID: 3511672 • Letter: P
Question
Please explain why D is the correct answer
4 pts. 6. Which one of the following statements about smooth muscle is incorrect? (d) a. The function of dense bodies in smooth muscle is similar to that of z-disks in skeletal muscle b. Although the mechanisms differ, the function of myosin light chain kinase in smooth muscle is c. In both smooth & skeletal muscle, myosin is a complex of 6 proteins: 2 heavy chains and 4 light d. An intracellular signaling pathway that increases activity of myosin light chain kinase and similar to that of troponin in skeletal muscle chains decreases the activity of myosin light chain phosphatase would likely cause relaxation of smooth muscle cells e. In a smooth muscle cell, inhibition of myosin light chain phosphatase would make the cell more sensitive to intracellular Ca2, i.e., a given increase in Ca2 would cause a stronger contractionExplanation / Answer
Option D. is incorrect.
Explanation - Contraction of smooth muscle occur by Phosphorylation of Myosil light chain (MLC). This process is catalysed by enzyme MYOSIN LIGHT CHAIN KINASE (MLCK). Increased intracellular Calcium induce activation of this enzyme which then phosphyrylate MLC thus initiating process of smooth muscle contraction. MLCK help in contraction of SM.
Relaxation of smooth muscle occur when this MLC is Dephosphyrylated (opposite to what happened during contraction) and the enzyme responsible for this is MYOSIN LICHT CHAIN PHOSPHATASE (MLCP). MLCP dephosphyrylate MLC (ie removes phosphate bond) and this inactivate MLC which then return to their normal/relaxed position. MLCP help in relaxation of SM.
From above two statements we see that in order to relax smooth muscle (The correct statements are) -
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