What explains the increased concentration of Ca⁺⁺ in the ER?
A) Calcium ions are actively imported from the cytoplasm into the ER.
B) Calcium concentration is kept low in the cytoplasm because of its high usage level.
C) Calcium cannot enter the plasma membrane through ion channels.
D) Calcium levels in the blood or other body fluids are extremely low.
E) The Ca ions are recycled from other molecules in the ER.

Question

Quizplus · Accepted Answer

Calcium ions are actively imported from the cytoplasm into the ER, which leads to an increased concentration of Ca⁺⁺ ions in the ER. This active transport process is carried out by Ca²⁺ pumps that use ATP to pump Ca²⁺ ions into the ER lumen. This helps to maintain a low concentration of calcium ions in the cytoplasm and allows the ER to function properly in processes such as protein folding and lipid synthesis.

What Explains the Increased Concentration of Ca⁺⁺ in the ER