Passive and Active Transport Flashcards
What are the (3) factors that determine transport rate?
Draw and describe how the glucose carrier works
Describe the kinetics of the GLUT1 transporter
What are the examples of couples transport discussed in class?
What is the difference between the glucose transporters?
Define chemical potential energy and electricochemicalpotential energy. How do you calculate these values? In what situation would the equation for electrochemical potential reduce down to Vm = E[ion]?
Na+/Glucose transporter (SGLT2 and SGLT1); Cl-/HCO3- exchanger; Na+/Ca2+ exchanger
SGLT2 >> 1:1 ratio; SGLT1 >> 2:1 ratio
Chemical potential energy: energy stored w/in bonds of the molecule itself
Electrochemical potential energy: basically chemical potential energy considering the charge contribution of the solute as well
How would you calculate the concentration of glucose that enters the cell via the SGLT 2 vs 1 transporters?
Since the SGLT1 mechanism creates a heavy osmotic load, how does the cell circumvent this problem?
Describe how the AE1 transporter works
Draw and describe how NCX1 (Na/Ca exhanger) works
Describe how the sodium potassium atpase/sodium pump works
Describe the roles of ouabain and degoxin/phospholemman in regulating the sodium pump
Oubain blocks the pump, which prevents Na+ from leaving the cell, thereby preventing afterhyperpolarization
Phospholemman binds the alpha subunit and reduces Na+ transport. When phosphorylated, PLM increases the pump’s affinity for Na+ and K+
Describe how the NCX circumvents the action of ouabain
What are the Ca2+ transporters discussed? Do all of these use ATP?
SERCA
NCX
PMCA
Nope. NCX used the Na+ gradient to drive Ca2+ entry into the cell.
Describe how SERCA, PMCA and NCX work. (i.e. which direction are these moving Ca2+)
SERCA = sarcoplasmic/ endoplasmic reticulum channel; pumps 2x Ca2+ inside
PMCA (Plasma membrane Calcium channel): pumps 1x Ca2+ out
NCX: usually pumps out 1x Ca2+ and 3x Na+ inside (can be reversed, depending on cell’s needs)
What are the 2 Cu2+ transporters discussed and how do they work?
ATP7A - Cu2+ absorption (export) from intestinal cells to interstitium
ATP7B - Cu2+ export from hepatocytes to bile
Which diseases result from defects in ATP7A and ATP7B?
Menke’s disease: ATP7A defect; inadeaquate Cu2+ absorption
Wilson’s disease: ATP7B defect: not enough C2+ export from liver = Cu2+ accumulation
Draw and describe the role of the H+/K+ ATPase.
Descibe how SGLT2 (Na-Glucose co transporter)
