Becker's World of the Cell 9th Edition by Lewis Kleinsmith, Jeff Hardin, Gregory Paul Bertoni

Exercise 5

Interpreting Data. Each of the following statements summarizes the results of an experiment related to exocytosis or endocytosis. In each case, explain the relevance of the experiment and its result to our understanding of these processes.
(a)Addition of the drug colchicine to cultured fibroblast cells inhibits movement of transport vesicles.
(b)Certain pituitary gland cells secrete laminin continuously but secrete adrenocorticotropic hormone only in response to specific signals.
(c)Certain adrenal gland cells can be induced to secrete epinephrine when their intracellular calcium concentration is experimentally increased.
(d)Cells expressing a temperature-sensitive form of dynamin do not display receptor-mediated endocytosis after a temperature shift, yet they continue to ingest extracellular fluid (at a reduced level initially, and then at a normal level within 30-60 minutes).
(e)Brefeldin A inhibits cholesterol efflux in adipocytes (fat cells)without affecting the rate of cellular uptake and resecretion of apolipoprotein A-I in adipocytes.