Final answer:
Multiple transporters performing one physiological task include the sodium-glucose symporter (SGLT) and GLUT proteins facilitating glucose uptake in cells; another example is the group translocation in bacterial cells through the phosphotransferase system.
Step-by-step explanation:
An example of multiple transporters performing one physiological task can be seen in the coordinated effort of transporter proteins in the absorption of glucose into cells. In the small intestine, the sodium-glucose symporter (SGLT) utilizes sodium ions to facilitate the uptake of glucose against its concentration gradient into intestinal cells. Cells also have GLUT proteins that allow glucose uniport, the transport of glucose on its own into cells.
Another example is the action of the sodium-potassium pump, which maintains a gradient that allows sodium ions to enter cells via a symporter, subsequently enabling glucose to be absorbed. Moreover, in bacterial cells, group translocation involves the modification of a molecule (e.g., glucose) via the phosphotransferase system as it is transported into the cell, preventing the necessity of transport against an unfavorable concentration gradient.
These transport mechanisms involve different types of carrier proteins, such as uniporters, symporters, and antiporters, to facilitate the movement of molecules across cell membranes. Uniporters transport a single molecule or ion, symporters move two different substances in the same direction, and antiporters exchange two different substances in opposite directions. These carrier proteins undergo allosteric changes during transport and can be regulated by different factors, such as the hormone insulin in the case of glucose transport in certain cells.