Question

Ca2+-pumps in the plasma membrane and endoplasmic reticulum are important for _____________.

(a) maintaining osmotic balance.
(b) preventing Ca2+ from altering the activity of molecules in the cytosol.
(c) providing enzymes in the endoplasmic reticulum with Ca2+ ions that are necessary for their catalytic activity.
(d) maintaining a negative membrane potential.

Answer 1

Ca2+-pumps in the plasma membrane and endoplasmic reticulum are vital for preventing Ca2+ from altering cytosolic activity, by using ATP to regulate Ca2+ concentration for signaling purposes.

Step-by-step explanation:

Ca2+-pumps in the plasma membrane and endoplasmic reticulum are important for preventing Ca2+ from altering the activity of molecules in the cytosol. The free concentration of calcium ions (Ca2+) within a cell is very low because ion pumps use adenosine-5'-triphosphate (ATP) to actively remove it, thereby regulating its concentration for cell signaling purposes.

Ca2+ is stored in the endoplasmic reticulum, or accessed from outside the cell, and when needed, it is released into the cytosol to activate various cellular responses such as insulin release from ß-cells or muscle contractions. These pumps are crucial for maintaining cellular function and signaling pathways.