Exam 2 Powerpoint 10 Flashcards
H and H experiments predicted
existence of channels
Predictions (4)
Channels must allow ions to move across the membrane at a high rate
Channels make use of electrochemical gradients
Discriminating –specific for specific ions
Voltage sensitive; inactivating in some cases
Technical impediment H and H faced
Voltage clamp allowed recording of
aggregate currents (thousands of channels): needed a new
method
Patch Clamping was invented in
1976
Patch clamping was made to
record activity of a single ion channel or whole cell currents
Patch clamping forms a
high resistance seal between cell membrane and glass wall of
the micropipette (apply suction)
Patch clamp recording allows
Allows recording from one ion channel
No ions escape b/c it is a very tight seal
Low level of background noise
Can alter the potential across the patch simply by applying
voltage to the pipette
https://www.youtube.com/watch?v=mVbkSD5FHOw
https://www.youtube.com/watch?v=TUoCQTwewVo
Sodium currents Recorded in the
presence of _____ which blocks
__________ channels
Cs+
Potassium
Macroscopic recordings are from
multiple channels
Microscopic recordings are from
1 channel
Depolarization increases the probability of
channel opening
Potassium currents
in in presence of _____
which blocks __________________
TTX
sodium
channels
___genes are associated with K channels
78
____genes are associated with Na channels
29
More than _____ genes encode for channels. Can vary due to RNA editing and splice variants.
230