[Campbell Biology P.274] Based on Figures 11.13 and 11.14, what is the primary functional di... | Practice Question

Based on Figures 11.13 and 11.14, what is the primary functional difference in terms of calcium ion Ca2+ transport between the Ca2+ pump shown in Figure 11.13 and the IP3-gated calcium channel shown in Figure 11.14?

  • A: The Ca2+ pump transports Ca2+ against its concentration gradient using ATP, while the IP3-gated channel allows Ca2+ to flow down its concentration gradient without direct ATP use.
  • B: Both transport Ca2+ against its concentration gradient, but the pump is found in the plasma membrane while the channel is in the ER.
  • C: The Ca2+ pump moves Ca2+ into the cytosol, whereas the IP3-gated channel moves Ca2+ out of the cytosol.
  • D: The Ca2+ pump is regulated by IP3, while the IP3-gated channel is continuously active.
  • E: Both are examples of passive transport, but they operate in different cellular compartments.

Explanation

The Ca2+ pump shown in Figure 11.13 uses ATP to actively transport Ca2+ against its concentration gradient from low concentration in cytosol to high concentration in ER lumen or extracellular fluid . In contrast, the IP3-gated calcium channel in Figure 11.14 is a passive channel that, when opened by IP3, allows Ca2+ to flow down its concentration gradient from high concentration in ER lumen to low concentration in cytosol without direct ATP consumption.