Cell biology quiz-1
2014/3/27
1. read the following observations and answer the question:
the neurotransmitter acetylcholine is made in the cytosol and then transported into
synaptic vesicles, where its concentration is more than 100-fold higher than that in the
cytosol. you isolated synaptic vesicles from neurons and suspended them in a solution
with similar compositions to the cytoplasm of the neurons. you found the following:
1) the synaptic vesicles can take up additional acetylcholine added to the solution in
which they are suspended, but only when atp is present.
2) na+ ions are not required for acetylcholine uptake.
3) when you raise the ph of the solution in which the synaptic vesicles are
suspended, the rate of the acetylcholine uptake also increases.
4) when you add a drug that makes the membrane of the synaptic vesicle permeable
to h+ ions, the transport of acetylcholine across the membrane is blocked.
question:
according to the observations above, suggest a mechanism for the accumulation of
acetylcholine in the synaptic vesicle in nerve cells.