What is the rate-limiting factor in the synthesis of acetylcholine

What is the rate-limiting factor in the synthesis of acetylcholine?
A.  The activity of choline acetyltransferase.
B.  The availability of acetyl-CoA.
C.  The activity of acetylcholinesterase.
D.  The availability of choline.
E.  The activity of butyrylcholinesterase.


Which of the following pairs are the structural units of the conjugate protein rhodopsin?
A.  Opsin and beta-carotene
B.  Opsin and vitamin A alcohol
C.  myosin and retinal
D.  myosin and beta-carotene
E.  Opsin and cis-retinal


The two pocket model used to explain the activity of acetylcholinesterase
A.  accounts for the changes in membrane potential.
B.  accounts for an acetyl-enzyme intermediate.
C.  suggests only a hydrophobic interaction with acetylcholine.
D.  is required to explain the post-translation action on the enzyme.
E.  requires covalent binding of choline.