Membrane Transport (Lecture 9) Flashcards
What would pure lipid bilayers only be permeable to?
gases, small uncharged polar molecules
True or False: Life wouldn’t be possible with a pure lipid bilayer.
True
A _____ K value means hydrophobic and easier to cross the lipid bilayer.
High
What are the 3 types of membrane transport protein ?
Channels
Transporters (uniporter, antiporter, symporter)
ATP-powered pumps
Channels move molecules ______ the concentration gradient.
Down
Uniporters move 1 molecule ______ the concentration gradient.
Down
______ and ______ transport 2 molecules: one down its concentration gradient, and one up its concentration gradient.
Symporter and antiporters
What is secondary active transport?
uses energy of an existing electrochemical gradient
True or False: ATP-powered pumps is the slowest form of transport.
True
True or False: ATP-powered pumps use energy of ATP hydrolysis to transport up a chemical concentration gradient, electric potential, or both.
True
What are the three types of free transport?
Simple diffusion, channel, uniporters
What are the three types of costly transporters.
Symporters, antiporters, ATP-powered pumps
True or False: Conformational changes are essential for transport proteins.
True
How do multiple membrane transporters work together?
Na+/K+ pump (ATPase) pumps Na+ out of the cell and K+ inward
Sets up gradients of Na+ and K+ across the membrane
Primary active transport
Na+/lysine symporter brings lysine into cell along with two Na+
Na+ gradient used to power import of lysine
Secondary active transport
K+ channel releases K+ down its gradient
Maintains electric potential across membrane (+ out, - in)
Facilitated transport
True or False: Uniport is faster and more specific than diffusion.
True
______ is the maximum transport rate (when all of the available uniporters have substrate and are working at the maximal rate)
Vmax
______ is a measure of affinity for the substrate (“how good it is at binding”), and is the concentration of substrate at half Vmax
Km
True or False: The partition coefficient is irrelevant when using a uniport.
True
True or False: The lower the value of Km, the more tightly the substrate binds to the transporter.
True
True or False: The higher the Km the faster the reaction.
False, the lower the Km
What is the first step in metabolism of glucose?
Phosphorylation
True or False: Conformational changes are reversible.
True
True or False: Aquaporins Increase Water Permeability of Cellular Membranes.
True
True or False: The aquaporin has conformational changes.
False, they do not
