Question

In certain kinds of muscle cells, calcium ions are stored in ________?

1) the smooth ER
2) the rough ER
3) both smooth and rough ER
4) the cytoplasm

Answer 1

In muscle cells, calcium ions are stored in the sarcoplasmic reticulum, a specialized form of the smooth endoplasmic reticulum.

Step-by-step explanation:

In muscle cells, calcium ions are stored in a specialized smooth endoplasmic reticulum (SER) known as the sarcoplasmic reticulum (SR). This storage is crucial for triggering the coordinated contractions necessary for muscle function. While the rough endoplasmic reticulum is involved in protein synthesis and has a distinct appearance due to the presence of ribosomes, it does not specialize in calcium ion storage. In contrast, the sarcoplasmic reticulum is adapted specifically for this role within muscle cells, aiding in the release and retrieval of calcium ions during muscle contraction.1) the smooth ER