Molecular Biology Of The Cell 6th Edition by Bruce Alberts, Alexander Johnson, Julian Lewis, David Morgan, Martin Raff, Keith Roberts, Peter Walter

Exercise 10

Discuss the following problems.
-1 Acetylcholine-gated cation channels at the neu- romuscular junction open in response to acetylcholine released by the nerve terminal and allow ions to enter the muscle cell, which causes membrane depolarization and ultimately leads to muscle contraction. a. Patch-clamp measurements show that young rat muscles have cation channels that respond to acetylcho- line (Figure Q11-4). How many kinds of channel are there? How can you tell? b. For each kind of channel, calculate the number of ions that enter in one millisecond. (One ampere is a cur- rent of one coulomb per second; one pA equals ampere. An ion with a single charge such as carries a charge of coulomb.)