AMP-PNP is the abbreviation for a structural analogue of ATP in which the second and third phosphate groups are linked by an NH group (instead of an oxygen atom). AMP- PNP can bind to the ATP-binding site of most ATPases. It differs from ATP in that the terminal phosphate cannot be removed by hydrolysis (so you cannot create ADP, therefore, you cannot get energy from AMP-PNP). Based on this information, explain the following

a. When isolated myofibrils are placed in a flask containing Ca2+ and AMP-PNP, contraction is quickly arrested. Where in the contraction cycle will contraction stop? Be specific.
b. What affects would you predict for cilia on a paramecium to which AMP-PNP is added? Be specific as to the proteins / molecules whose function would be inhibited and what would be the overall affect?
c. When researchers incubated purified vesicles, axoplasm (containing motor proteins), and MT from the giant squid axon and added AMP-PNP, the vesicles did not move along the MT. Explain this observation using specific proteins / processes affected.