Lec 9-10 Flashcards
Channel and pump proteins allow for the passive and active
displacement of which key ions?
sodium, chlorine, and potassium
What is the resting membrane
potential:
-70 millivolts (inside is 70mV lower than outside).
The resting potential is the voltage difference of the plasma membrane before any action potential
Whar do we call the way information travels through the nervous system?
Propagation of an action potential
The plasma membrane is modelled as an electrical circuit by… (model name)
Hodgkin-Huxley Model
Draw and explain the Hodgkin-
Huxley Model. In this model what is represented by the components of the circuit?
◆ The caparictor represents…
◆ The resistors represent…
◆ The batteries represent…
◆ The current sources represent…
In this model:
◆ The lipid bilayer is represented by the capacitance (C)
◆ Voltage-gated ions channels are represented by the resistors (g)
◆ The electrochemical gradients driving ion flow are represented by the batteries (V)
◆ The active pumps are represented by the current source in the circuit (between
“Extracellular” and “Intracellular” above)
Explain the “N-doped” area of the P-N (or N-P) junction.
In the “N-doped” area, group 5 elements are added in small quantities. The single fifth
electron will be mobile in the system.
Explain the “P-doped” area of the P-N (or N-P) junction.
In the “P-doped” area, group 3 elements are added in
small quantities. The “gap” left by the missing valence electron will lead to current generation when free electrons from the N-doped region migrate to the P-doped region.
The potential of a membrane can be computed using either the Nernst equation or Goldman equation. Whats the difference in how they should be used.
Goldman equation takes into account all ions, each with their difference in permeability across the membrane, whereas Nernst equation considers only the membrane potential of one ion.
Describe what the patch clamp technique is.
This technique involves touching the membrane with a sharp pipette tip containing liquid. As
ions move in and out of the pipette, a small current can be measured. This allows for the study
of individual ion channels in the membrane.
Lipid rafts form as a result of what?
The natural motion of the membrane and phase separation (the aggregation of similar molecules).
Phase separation explains what model of the membrane?
Phase separation causes compartmentalization within membranes, creating the fluid mosaic model. It is split into actin-induced compartments each with its mesoscale raft domain.
What ions tend to be outside the cell and which ones inside the cell in the resting membrane potential state? What is the charge on either side? Where is the charged concentrated?
Extracellular space: Na+, Cl- (net positive charge)
Intracellular space: A4- K+ (net negative charge)
The charge is concentrated along the cell membrane.
What structures are used to allow facilitated diffusion?
Transmembrane integral proteins. Specifically ion channels.
What structures are used to allow to transport ions aginst the concentration gradient?
Ion pumps.
Describe how Resting K+ Channels work
Resting K+ Channels:
● Generate the resting potential across the
membrane
Voltage-Gated Channels work?
Voltage-Gated Channels:
● Responsible for propagating action potential
along the plasma membrane in neurons
● A specific voltage (provided by a stimulus) is
needed to activate these channels