62.4k views
0 votes
Which of the following statements about calcium ions is true?

Ca2+ enters cells through Ca2+ channels that can be voltage-, ligand- or mechanically-gated.

Most intracellular Ca2+ is stored within the nucleus.

Ca2+ binds to the protein calmodulin.

Ca2+ binding to the regulatory protein troponin initiates muscle relaxation.

Ca2+ binding to regulatory proteins triggers endocytosis of secretory vesicles.

The Ca2+ concentration is higher in the ECF compared with the ICF.

User Amateur
by
8.5k points

1 Answer

1 vote

Final answer:

Calcium ions (Ca2+) enter cells through various gated channels and bind to proteins like calmodulin and troponin, triggering physiological responses such as muscle contractions. Highest Ca2+ concentrations are present in the extracellular fluid. Ca2+ plays a versatile role in cellular processes.

Step-by-step explanation:

Among the statements provided about calcium ions (Ca2+), there are certain true aspects relevant to Ca2+ physiological roles and mechanisms in the cell:

Ca2+ enters cells through Ca2+ channels that can be voltage-, ligand-, or mechanically-gated.

Ca2+ binds to the protein calmodulin.

Most intracellular Ca2+ is stored within cytoplasmic compartments such as the sarcoplasmic or endoplasmic reticulum, not the nucleus.

Ca2+ binding to the regulatory protein troponin initiates muscle contraction, not relaxation.

Ca2+ concentration is higher in the extracellular fluid (ECF) compared with the intracellular fluid (ICF).

The exchange of Ca2+ through cellular mechanisms is crucial for various cellular processes, including muscle contractions and neurotransmitter release at synapses. The role of Ca2+ is multifaceted, depending on the cell type and context within the physiological processes.

User Slanden
by
8.5k points
Welcome to QAmmunity.org, where you can ask questions and receive answers from other members of our community.

9.4m questions

12.2m answers

Categories