6.19-6.21 Flashcards
2 of the major components of the electrochemical gradient across the euk pm
Na+ and K+
what does the (-) resting membrane potential regulate
- osmotic pressure
- allows for secondary Na+-dependent transport of molecules
Na+/K+ belongs to family of ________________
P-type ATPases
P-type ATPases
autophosphorylates aspartic acid residue as an intermediate during ion transport
- terminal phosphate transferred from ATP to active site in the enzyme
for each ATP hydrolyzed, the Na+/K+ ATPase does what?
move 3 Na+ out and 2 K+ in
true or false: the Na+/K+ ATPase is reversible
true: but not under physiologic conditions
what would a reversible Na+/K+ ATPase look like
Na+ in and K+ out: net inward current
what targets the Na+/K+ ATPase
plant steroids like cardiac glycosides
ex. of cardiac glycosides
ouabain, digitalis
what do plant steroids specifically do to the Na+/K+ ATPase
inhibit ion transport
where is digitalis from
foxglove plants
how can digitalis be used to treat heart failure
- inhibits transport of Na+
- higher cytosolic Na+ concentration
- Ca2+ can’t be pumped out as efficiently, leading to higher cytosolic Ca2+ concentration
- Ca2+ increases contractility of the heart
purpose of F1F0 -ATP synthase
couples energy of proton gradient (proton motive force) to ATP synthesis
where is F1F0 -ATP synthase in proks
plasma membrane
where is F1F0 -ATP synthase in euks
mitochondrial inner membrane
F0 region of F1F0 -ATP synthase
- transmembrane
- involved in translocation of protons down their electrochemical gradient
- rotates
F1 region of F1F0 -ATP synthase
- globular domain
- contains catalytic sites responsible for ATP synthesis
where is F1 region in proks
cytoplasmic side
where is F1 region in euks
mito matrix side
how many protons are transported per ATP synthesized for the F1F0 -ATP synthase
4
true or false: the F1F0 -ATP synthase can work in reverse
true
vacuolar-type proton pumps
H+-ATPases that are essential for maintaining the pH of organelles such as lysosomes and endosomes that ned a more acidic environment than the cytosol
2 functional domains of H+-ATPases
- V1
- V0
V1
- cytosolic
- binds and hydrolyses ATP for energy for proton translocation
V0
- membrane-bound
- where proton translocation occurs
