Phosphate Ion Has the Structure PO₄³⁻

question 71

Multiple Choice

Phosphate ion has the structure PO₄³⁻.This ion is reversibly added to and removed from many different protein molecules in the cell as a means of regulating the proteins' functions.Water's solvent properties are important in understanding the modification of proteins by phosphate ion because

• A) biochemists use water as the solvent in laboratory experiments aimed at mimicking the internal workings of a cell.
• B) when proteins are removed from cells and placed in solvents from the lab, their functions change.
• C) the external cell environment is composed of water, and many signaling molecules move through aqueous environments to bind to receptors on cell surfaces.
• D) the internal cell environment is composed of water, and all cellular reactions occur within this aqueous solvent.
• E) the phosphate ion has different solubilities in different solvents.

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