In intestinal epithelial cells, a transport protein moves glucose into the cytoplasm against its concentration gradient at the same time that it transports Na⁺ into the cell down its electrochemical gradient. Which of the following CORRECTLY describes this cotransport of glucose and sodium? A)Primary active transport by a symporter. B)Secondary active transport by an antiporter. C)Secondary active transport by a symporter. D)Primary active transport by an antiporter.

Question

Quizplus · Accepted Answer

The movement of glucose into the cell against its concentration gradient implies that an energy source is required, making it an example of secondary active transport. Furthermore, the fact that Na⁺ is also transported into the cell down its electrochemical gradient suggests that it is being used as the energy source to move glucose against its gradient. This is indicative of symport, where two substances are transported in the same direction across a membrane. Therefore, the correct choice is secondary active transport by a symporter (choice C).

In Intestinal Epithelial Cells, a Transport Protein Moves Glucose into the Cytoplasm