1 Flashcards
The cell membrane is made of a __________ that is impermeable to __________.
Phospholipid bilayer,
ions.
Ion channels are ________, which means
transmembrane proteins,
They’re made of a string of amino acids in a simple sequence.
A typical ion channel doesn’t just have _____ alpha helix
one
Ion channels are made of what?
Proteins
What structural feature of an ion channel spans the lipid membrane?
Alpha helix
The ion channel pore is largely composed of what?
Water
Which statement about transporters is NOT true?
- Transporters move ions at slower rates than ion channels.
- Transporters passively transport ions along the electro-chemical gradient.
- Transporters do not have an aqueous pore.
Transporters passively transport ions along the electro-chemical gradient.
Ion channels are characterized by gating and ______.
selectivity
Ion channels can flip from open (conducting) to closed (non-conducting) states on the _______ timescale.
microsecond
Changing the open probability of ion channels is an important way to regulate transmembrane _____.
current flow
Selectivity is a preference of ion channels to conduct a _____.
specific ion
The degree of selectivity can vary between different _______.
ion channels
There are _____ types of non-selective channels
many
Transporters move ions at a _____ rate than ion channels
slower
Transporters can work against the ______.
electro-chemical gradient
Transporters do not have an _____ pore.
aqueous
The ______ causes an attraction or a repulsion for ions of a given charge.
membrane potential
If there is a negative potential on the inside, then _____ ions will be attracted inside, down the electric-field gradient.
potassium
One major determinant of ionic movement across ion channels is the _______. The other major push that moves ions from one side of a membrane to another is _______.
electric field,
concentration.
______ and ______ gradients are the two main forces that drive electrochemical diffusion across the plasma membrane.
electrical,
concentration.
If we make the inside of a cell more negative, then that will then try to attract _____ ions inside the cell.
positive
The potassium ions are high ________, and low ______.
intracellularly (at about 150 mM)
extracellularly (aroung 4 mM)
Sodium ions are low _______, and high _______.
inside cells (around 12 mM)
outside the cell (140 mM)
Chloride concentration is low ______ the cell, and high ______ the cell.
inside (4 or 5 mM)
outside (120 mM)
