Question

Intracellular calcium levels are kept in the submicromolar range (<10-6 molar) by which of the following mechanisms?

A. Calcium pumps in the plasma membrane.
B. Calcium-binding proteins.
C. Calcium channels in the endoplasmic reticulum.
D. All of the above.

Answer 1

Intracellular calcium levels are maintained in the submicromolar range by calcium pumps, calcium-binding proteins, and calcium channels in the endoplasmic reticulum.

Step-by-step explanation:

Intracellular calcium levels are kept in the submicromolar range (<10-6 molar) by all of the above mechanisms.

1. Calcium pumps in the plasma membrane continuously remove calcium ions from the cytoplasm.
2. Calcium-binding proteins help to buffer and regulate the concentration of calcium ions in the cytoplasm.
3. Calcium channels in the endoplasmic reticulum can release stored calcium ions into the cytoplasm when needed.

These mechanisms work together to maintain the low concentration of intracellular calcium, which is essential for proper cellular function.