A Number of Systems for Pumping Ions Across Membranes Are

question 31

Multiple Choice

A number of systems for pumping ions across membranes are powered by ATP. Such ATP-powered pumps are often called ATPases, although they do not often hydrolyze ATP unless they are simultaneously transporting ions. Because small increases in calcium ions in the cytosol can trigger a number of different intracellular reactions, cells keep the cytosolic calcium concentration quite low under normal conditions, using ATP-powered calcium pumps. For example, muscle cells transport calcium from the cytosol into the membranous system called the sarcoplasmic reticulum (SR) . If a resting muscle cell's cytosol has a free calcium ion concentration of 10⁻⁷ while the concentration in the SR is 10⁻², then how is the ATPase acting?

• A) ATPase activity must be powering an inflow of calcium from the outside of the cell into the SR.
• B) ATPase activity must be transferring ᵢ to the SR to enable this to occur.
• C) ATPase activity must be pumping calcium from the cytosol to the SR against the concentration gradient.
• D) ATPase activity must be opening a channel for the calcium ions to diffuse back into the SR along the concentration gradient.

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Definitions:

Division Revenues

The total amount of income generated by a specific division or section of a company through its operations and sales.

Parent Company

A company holding a sufficient amount of another firm's voting shares to influence or determine its board of directors, thereby controlling its management and operational decisions.

Incentives

Benefits or rewards offered to encourage specific actions or behaviors.

Divisional Conflict

Conflicts that arise within sections of an organization, often due to differing objectives, resources, or priorities.