Question

[Ca2+] within the endoplasmic reticulum (ER) is 10-3M. Cytosolic [Ca2+] is 10-7M. Lysosomes in mammalian cells have an internal pH of 4.0. Cytosolic pH of a typical mammalian cell is 7.0. Which transport reaction has a greater (more positive) Delta Gc, H+ import into lysosomes or Ca2+import into the ER?

A.

H+ import into the lysosome because it has the steeper concentration gradient.

B.

Ca2+ import into the ER because it has the steeper concentration gradient.

C.

H+ import into the lysosome because it is a monovalent cation.

D.

Ca2+ import into the ER because it is a divalent cation.

E.

Delta Gc is the same for both ions because their concentration gradients are the same.

Answer 1

For deta G positive the reaction must be non spontaneous that means transport must be occurs opposite to the concentration gradients. Concentration of H and is Greater in lysosome and concentration of calcium ion is Greater in endoplasmic reticulum show the direction of passive transport is from lysosome to cytoplasm and from endoplasmic reticulum to cytoplasm. But for Greater value of deta G the direction of transport must be opposite. And the answer will be A and B