29 Figure Q12-4 shows a recording from a patch-clamp expeniment in which the electrical current passing across a patch of membrane is measured as a function of time The membrane patch was plucked from the plasma membrane of a muscle cell by the technique shown in figure 12-24 in the textbook and contains molecules of the acetylcholine receptor, which is a ligand-gated cation channel that is opened by the binding of acetylcholine to the extracellular face of the channel To oblain a recording acetyicholine was added to the solution inside the microelectrode a) Describe what you can learn about the channels from this recording b) How would the recording difer if acetylcholine were () omited or (il) added to the solution outside the microelectrode only? 2 pA 10 msec Paragraph ▼ |B 1 |ΕΞΙίΞ A) from, this channel you visualize the action potential generated by applying a stimulus 29 Figure Q12-4 shows a recording from a patch-clamp expeniment in which the electrical current passing across a patch of membrane is measured as a function of time The membrane patch was plucked from the plasma membrane of a muscle cell by the technique shown in figure 12-24 in the textbook and contains molecules of the acetylcholine receptor, which is a ligand-gated cation channel that is opened by the binding of acetylcholine to the extracellular face of the channel To oblain a recording acetyicholine was added to the solution inside the microelectrode a) Describe what you can learn about the channels from this recording b) How would the recording difer if acetylcholine were () omited or (il) added to the solution outside the microelectrode only? 2 pA 10 msec Paragraph ▼ |B 1 |ΕΞΙίΞ A) from, this channel you visualize the action potential generated by applying a stimulus
From the figure, it can be understood that when the cation channel is opened, the ion moves across it and creates either a positive or a negative current. A positive current is flowing through the cation channel as seen in the figure. Current readings will be absent in both the cases when acetylcholine is omitted or added in the solution outside the microelectrode. The current readings upon acetylcholine binding will only be given by the gated cation channel that spans the microelectrode tip.
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