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34 Cards in this Set

  • Front
  • Back
What type of molecules do not require a transport mechanism?
lipid-soluble molecules, typically hydrophobic
What type of barrier is the cell membrane?
selectively permeable
What is passive transport? active?
Passive - 1 molecule using a channel or transporter and goes down its concentration gradient
Active - Requires energy from either ATP or symport or antiport of 2 or more molecules
What are 3 ways of driving active transport? Why is active transport required?
Coupled, ATP, light (bacteria)
moving a molecule against the gradient
What is the term for maintenance of physiological variables within precise limits?
What is the positive Ca feedback system in T cells?
Ca released through IP3R -> Ca binds IKCa1 which releases K+ from the cell -> creates an electromagnetic gradient -> allows CRAC channel to let more Ca into the cell
That will eventually activate a promoter
What is a CRAC channel? Once opened when does it close?
Ca release-activated Ca channel
When intracellular [Ca] reaches a certain level, it closes. called negative feedback
What moves molecules faster a channel or a transporter?
What do symport and antiport do?
use one molecule with its concentration gradient to push another molecule against its concentration gradient, active transport
Explain Na, K, Glu interactions in lumen of intestine.
1. Symport of Na and Glu, Na with the gradient, Glu against. from the lumen
2. Antiport of Na and K. K travels with its gradient into the cell to push Na out of the cell into the paracellular space
3. Glu leaves the cell as a uniporter into the capillary
What are the three types of ATP pumps and describe them?
1. P-type - uses phosphate and energy from ATP to move ions out of cell
2. F-type (V-type) proton pump - makes ATP from ADP & Pi
3- ABC transporter - hydrolyzes 2 ATP to move the two sides of the pump
What is an example of a p-pump? the one used in t-cells to get 2 Ca into the cell?
SERCA pump. moves 2 Ca+
What is the most common CFTR mutation in humans?
(Cystic fibrosis something) what is the channel regulated by?
what does the mutation mess up?
delta F508
enzyme activity
protein folding
What domain is unique to CFTR?
R domain
What is the difference between channel activity in wild type CFTR and in CF mutants? graphed current/s
Wild type has many peaks so plentiful chloride release
mutants not nearly as many peaks so chloride release is minimal
What is the biggest thing targeted by current drug therapies?
What can control the gates of ion channels?
membrane potential, neurotransmitters, second messengers (ligands), environment (hot/capsaicin, cold/menthol, stretch/shear)
What is a non-selective ion channel?
channel that would allow several ions to pass
What is a VSD and PD for gating mechanisms?
VSD: voltage sensing domains
PD: pore domain
How do voltage sensing domains work?
They have a series of positive amino acid residues (Arginine) that reside in the membrane. When the membrane potential changes, they are forced outside the membrane, which causes a conformational change of the pore domain
What is the ball and chain model?
When the membrane is polarized, the channel is closed.
Depolarized - channel is open, but can be inactivated by sticking the ball (NH2) into the open channel.
Why is ion selectivity important? What are 2 key factors to selectivity?
Allows selective transport
Size and shape
What are common amino acids in coding for pore loops of channels?
What makes a K+ channel selective?
In the filter, it makes 4 transient bonds which give the energy to break bonds with water.

A Na+ molecule can't form all the same bonds so it is usually pushed out of the filter
What provides the selectivity of potassium channels?
of Calcium channels?
backbone carbonyl groups
Ca: Glu/Asp side chains
What was the point mutation on the Orai of CRAC? and what did it do?
It was changing a glutamic acid into a aspartic acid.
Altered the functionality of the ion filtering site such that Ca flows out of the cell (outward rectifying) instead of into the cell (inward rectifying)
What is the simplest voltage clamp? what does it allow?
A single pipette with no feedback amplifier
single channel resolution at millisecond time scale
Ion channel configurations: 1. Cell-attached, 2. inside-out, 3. outside-out, 4. whole-cell, 5. perforated-patch
1. pipette is sealed on the cell and left attached
2. pipette removes a channel with a bubble putting into the pipette
3. pipette removes a bubble with the bubble facing away from the pipette
4. pipette creates a gap straight into the cytoplasm of cell
5. modified cell-attched with stuff in the pipette
What is a calcium buffer called, and what are two examples?
EGTA and BAPTA, chelators
What are two properties of calcium indicators? And what can fluorescence be used to do?
They need to bind Ca and to be visible so give off fluorescence

Find concentrations
What percentage of the human genome do ion channels account for?
What are the 4 classes of mammalian K+ channels?
One Pore - 1: 2 transmembrane segments(2T). 2: 6T
Two pore - 1: 4T
2: 8T
What ion channelopathies look like in the:
1: CNS
2: Heart
3: Skeletal muscle
4: Vascular smooth muscle
1: Seizures, ataxia, migraine
2: Arrhythmia
3: paralysis, myotonia, paramyotonia, hyperthermia
4: hypertension
What ion channelopathies look like in the:
1: Renal
2: lung
3: Endocrine
4: T cells
1: electrolyte abnormalities
2: cystic fibrosis
3: diabetes
4: severe combine immune deficiency