APU Biology Maintaining Organ Hemostasis Worksheet

1.You monitor the movement of marvelous macrophages. You find that upon injection of the drug phalloidin, your macrophages show a transient increase in cellular extensions and movement at the leading edge of the cells. Interestingly, this forward movement of the cells stops almost immediately. Describe at least one possible explanation. Assume that the external chemoattractant, which stimulates cell movement, is unchanged during the experiment.

2.You isolate muscle tissue from the stiff rats and treat it with a non-hydrolyzable analog of ATP. What orientation do the myosin-ATP heads have with respect to actin?

45 degree? parallel? perpendicular?

3.i) First you put it in a low-calcium buffer with ATP; this treatment causes the muscle to relax. Why? choose one [ Select ] [“Myosin reorients itself with respect to actin“, “Tropomyosin reorients itself with respect to actin“, “Actin reorients itself with respect to tropomyosin“, “Tropomyosin reorients itself with respect to myosin“]

ii) Next you move the same muscle cells into a high-calcium buffer with ATP. What will happen to the cells? choose one [ Select ] [“Tropomyosin releases troponin“, “Troponin releases tropomyosin“, “Actin releases tropomyosin“, “Troponin reorients itself with respect to actin“]

iii) You add an antibody to troponin, then move the cells back to a low-calcium buffer with ATP. How does this effect the cells? choose one – nothing , Relaxes, contract