Intracellular Neurotransmission Flashcards
Circle the best answer
(Electrical/Chemical) signals used for long-distance (Intra/within neurons)
Electrical
Circle the best answer
(Electrical/Chemical) signals used for short-distance (Inter/between neurons)
Chemical
True or False
Fast intracellular communication within neurons used for long-distance is primarily mediated by V.G. Ion Channels
True
True or False for the following statements
__ Axon is 10m.
__ Corticospinal tract is the largest nerves in the body
__ Electrical signals take about 10-100msec.
False, Axon is 1m.
False, Sciatic nerve is the largest nerves in the body
True
Complete the sequence of ion channel activation and inactivation that occur during an action potential. (Use the image to help to answer)
Initial depolarization changes membrane potential from rest (___mV)
To (activate/inactive) threshold potential of V.G. (Na+/K+/Cl-) (____mV)
Leading to the V.G. (K+/Na+/Cl-) channels to open allowing _____ ions to flow in (mass amount)
Membrane potential changes from (____mV) to (____mV)
V.G. (K+/Na+/Cl-) channels (activate/inactive) and delayed V.G. (K+/Na+/Cl-) channels to open
Causing the opposite current, damper the curve of Action potential
Membrane potential chnages from ____mV back to _____mV.
-70mV
activate ; Na+ ; -55mV
Na+ ; Na+
-70mV ; 40mV
Na+ ; inactive; K+
40mV ; -70mV
What is the real reason for the Action Potential?
(Hint: It is an ion that causes physiological changes, a key mediator of cellular electrical activiity)
Ca2+
V.G. Ca2+ channels open, Ca2+ rush in
Coupling the membrane potential to intracellular events
What does the effect of Ca2+ influx result in this system?
In Skeletal muscle? __________
In neurons or neurons to skeletal muscle? ____________
In Excitation-transcription? ______________
In excitation-metabolic? _______________
Excitaion-contraction
Excitation-secretion
Turn on gene expression
Affect on mitochondria
What are the modular domains of the voltage-gated ion channel subunits?
Voltage Sensor Module is the first four subunits
The Linker/Coupling Module is the protein connecting 4 and 5 subunits.
Channel/Pore Module is the 5 and 6 subunit.
The Voltage sensor module will act independently and while it is activated, the linker will perform allosteric coupled to yield the channel to open an influx of ions.
True or False for the following statements
____ The Voltage sensing module(VSM) for Kv channels are S1-S4.
____ The VSM subunits move dependently.
____ The S4 segmented instead of having hydrophobic a.a. in the membrane is has positive charge a.a. at every third position.
____ When depolarization occurs it will induce a local change in the S4 segment and then the VSM which will allosteric coupled to a local change in pore activation gate, making the Kv channel open and active.
____ Bacterial Proto-K Channels were not voltage-gated. The VSM was basically added to create a voltage-gated ion channel.
True
False, The VSM subunits move independently. When one subunit depolarize, each subunit move to the active phase while the pore remains close until all subunit is active that is when the pore is open. (Allosterically coupling occurs)
True
True
True
What is one distinct difference between the V.G. K+ channels and the V.G. Na+ channels?
V.G. Na+ Channels are made by one subunit with pseudo subunits that fused together to become a pseudo tetramer.
How do the pseudo subunits interact with one another to form the channel>
Pseudo dimer fused together to become a pseudo tetramer and assemble in a water-like cavity.
True or False
Nav and Cav channels in humans are in different genes and have different cell tissue expression. A mutation to their gene will cause a disease impact.
True
Ion channel permeability
(Na+/K+) channels can have a flux rate of 10^6 ions/sec
can select (Na/K) over (K/Na)
They can do this by using a ___________
If it is blocked then it can not filter the ions
K+
K+
Na+
selective filter
How does inactivation occur in most V.G. Na+ channels and a certain v.g. K+ channels
Ball and chain model, the ball is swinging randomly in the cytosol
When researchers will looking at fruit flies and saw that wildtype flies had a rapid activating/deactivating current on top of a sustained current and comparing that with mutant flies that had the slow sustained current only.
What did the researcher hypothesis?
What were the methods?
Why is this related to K+ channels?
That the shake gene encodes K+ channel
They mapped the gene, they cloned it and that is where they got the gene structure and sequence of K+ channel.
They immediately realized that 4 of these subunits come together to form a channel.
