Rank the sequence of events at the nmj that initiate an action potential in the muscle fiber, from first to last.

- action potential arrives at the axon terminal.
- acetylcholine binds to its receptors on the junctional folds.
- calcium ions enter the axon terminal.
- synaptic vesicles fuse to membrane of axon terminal.
- junctional folds become depolarized.
- action potential is initiated on the sarcolemma.
- acetylcholine is released into the synaptic cleft.

The correct order is:

- Action potential arrives at the axon terminal.

- Calcium ions enter the axon terminal.

- Synaptic vesicles fuse to membrane of axon terminal.

- Acetylcholine is released into the synaptic cleft.

- Acetylcholine binds to its receptors on the junctional folds.

- Junctional folds become depolarized.

- Action potential is initiated on the sarcolemma.

Action potential travels through the membrane of the presynaptic cell causing the channels permeable to calcium ions to open. Ca2+ flow through the presynaptic membrane and increase the Ca concentration in the cell which will activate proteins attached to vesicles that contain a neurotransmitter (e.g. acetylcholine). Vesicles fuse with the membrane of the presynaptic cell, thereby release their contents into the synaptic cleft-space between the membranes of the pre- and postsynaptic cells. Neurotransmitter binds to its receptors on the postsynaptic membrane and its binding causes depolarization of the target cell (muscle cell).

enzyme active site and substrate specificity

enzymes bind with chemical reactants called substrates. there may be one or more substrates for each type of enzyme, depending on the particular chemical reaction. in some reactions, a single-reactant substrate is broken down into multiple products

1. what is the relationship between the shape of an enzyme and the reactions they catalyze?

2. how does an enzyme inhibitor work?

separate your answers so i dont get confused : )