Membrane Transport Flashcards
A high partition coefficient (Kow) indicates that a molecule is
highly oil-soluble
An aquaporin is
a transmembrane water channel constitutively allowing passive
diffusion
An ion channel which opens when a molecule binds to it is
ligand-gated
Two molecules being transported in the same direction across a
membrane is an example of
symport
Facilitated diffusion generally requires
a change in conformation of a transmembrane carrier protein
Rate of uptake via facilitated diffusion graph description
approaches an asymptote which indicates Vmax
A low Km for a substrate indicates
high affinity for its transporter
GLUT-1
ubiquitous- low Km for glucose
GLUT-2
Liver, pancreatic beta cells- high Km and high Vmax for glucose
GLUT-3
Brain- transports glucose in the brain
GLUT-4
Muscle, adipocytes- insulin recruits transporter to membrane
GLUT-5
Fructose
GLUT1-4 transporters transport glucose via
facilitated diffusion
The transporter with a high Km and high Vmax for glucose is useful
when blood glucose levels are high
Na⁺/K⁺-ATPase in the sarcoplasmic reticulum is an example of
primary active transport
The binding of sodium in Na⁺/K⁺-ATPase causes a conformational
change via
Autophosphorylation of the transporter
A drug which blocks Na⁺/K⁺-ATPase is
oubain
Heart failure may be helped by blockade of Na⁺/K⁺-ATPase due to
an increase in intracellular Ca²⁺ concentration
SGLUT
important for the absorption of dietary glucose
Na⁺/K⁺-ATPase moves
sodium out, potassium in, in a 3:2 ratio
Secondary active transport is used in cholera treatment to
drive sodium replacement via a high intestinal glucose concentration
Vibrio cholerae causes over-secretion of
Cl
