Cell biology help The figure (Figure 2) below shows the pathway through which ni

Question

Cell biology help

The figure (Figure 2) below shows the pathway through which nitric oxide (NO) triggers smooth muscle relaxation in a blood-vessel wall. Which of the following situations would lead to relaxation of the smooth muscle cells in the absence of acetylcholine? Explain your answer.

a) A smooth muscle cell that has a defect in guanylyl cyclase such that it cannot bind NO.

b) A muscle cell that has a defect in guanylyl cyclase such that it constitutively converts GTP to cyclic GMP.

c) A muscle cell that has cyclic GMP phosphodiesterase constitutively active.

d) A drug that blocks an enzyme involved in the metabolic pathway from arginine to NO

acetylcholine activated NO synthase NOS arginine NO RAPIDDIFFUSION OF NO ACROSS MEMBRANES endothelial cell Figure 16-11b Essential Cell Biology,4th ed. (PGarland Science 2014) NO bound to guanylyl cyclase cyclic GTP GMP RAPID RELAXATION OF SMOOTH MUSCLE CELL smooth muscle cell

Explanation / Answer

ANSWER IS OPTION B

A MUSCLE CELL THAT HAS A DEFECT IN GUANYLYL CYCLASE SUCH THAT IT CONSTITUTIVELY CONVERTS CTP TO CYCLIC GMP.

IN ABSENCE OF ACETYLCHOLINE NITRIC OXIDE ACTS AS REGULATORY MOLECULE DIFFUSES INSIDE THE CELL AND ACTIVATE THE GUANYLYL CYLASE LOCATED IN CYTOSOL OF TARGET CELL CONVERTING GTP O CYCLIC GMP

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