Lecture 9

Question 1

Plasma Membrane Structure

Answer 1

The membrane is formed by a phospholipid bilayer
● Cells interact with their external environment through the plasma
membrane
● Phospholipid bilayer is a great example of self-assembly with purpose

Question 2

Resting K+ Channels

Answer 2

Generate the resting potential across the
membrane
● The resting potential is the voltage difference
of the plasma membrane before any action
potential
● The resting potential is usually around ~70
mV

Question 3

Voltage-Gated Channels

Answer 3

Responsible for propagating action potential
along the plasma membrane in neurons
● A specific voltage (provided by a stimulus) is
needed to activate these channels

Question 4

Ligand-Gated Channels

Answer 4

Have a binding site for a specific
extracellular neurotransmitter, which
when bound activates the channel
● Respond to external stimuli

Question 5

Signal-Gated Channels

Answer 5

Respond to intracellular signals
resulting from a neurotransmitter
binding to a distant receptor

Question 6

hodgkin-huxley model

Answer 6

Question 7

Calculating electric potentials across plasma
membranes

Answer 7

Question 8

Positive-Negative (P-N) Junction

Answer 8

Electrical current only passes through the junction in one direction

Question 9

Doping

Question 10

Explain why the lipid
bilayer can be modelled as a
capacitor.

Answer 10

A capacitor consists of two conducting surfaces,
separated by an insulator. Capacitors are used to
store charge in electric circuits.
The phospholipid bilayer is an excellent insulator
separating the intracellular and extracellular ionic
(conducting) media, it is functionally equivalent to
a capacitor.
The insulating properties of the membrane allow
it to hold enormous electrical charge.