Question

Researchers conducted an experiment to investigate the effects of a valinomycin treatment on skeletal muscle cells. Valinomycin is a naturally occurring substance that can be used as a drug. The results of the experiment are presented in the table. Which of the following claims about the effects of the valinomycin treatment is best supported by the data presented in the table?
A. The valinomycin treatment caused an increase in the activity of the rough endoplasmic reticulum.

B. The valinomycin treatment caused an increase in the activity of the Golgi complex.

C. The valinomycin treatment caused a decrease in the activity of the lysosome.

D. The valinomycin treatment caused a decrease in the activity of the mitochondria.​

Answer 1

The valinomycin treatment caused a decrease in the activity of the mitochondria.  

Explanation:

When valinomycin treatment was given, the rate of ATP production is reduced in the cells treated. Since mitochondria are involved in ATP synthesis, it clearly shows that valinomycin inhibits mitochondrial action.  

Valinomycin being a selective K+ ionophore, it can transfer potassium ions through selective lipid membranes. This can cause potassium effux in organelles like mitochondria leading to marked loss of potential of mitochondrial membrane and apoptosis in cells.

The effux of K+ ions forms a complex with valinomycin and slows down the mitochondrial part of ATP synthesis by reducing the proton-motive force, but does not block any oxygen electron transfer .