Glucose enters the epithelial cells of the small intestine against its concentration gradient. Select the BEST explanation from
the following. Glucose is co-transported in the Na /K pump. Glucose is co-transported with Na , which moves down its concentration gradient into the cell. Glucose follows the water that is pumped into the cell. Glucose is transported through a glucose pump in the apical membrane that hydrolyzes ATP to ADP and Pi. Glucose enters by diffusion.
Glucose is co-transported with Na , which moves down its concentration gradient into the cell.
Explanation:
Na/K pump is a pump located on the plasma membrane which uses ATP to move 3 Na ions out the cell and brings in 2 K ions into the cell. It is an example of primary active transport. As a consequence,concentration of Na is higher outside the cell, while K concentration is higher inside the cell.
Glucose is transported in the cell against its gradient, together with Na ions (symport) which move down their concentration gradient.
This is an example of secondary active transport because it uses the energy from the primary active transport to move other substances such as glucose against their own gradients.
Colchicine inhibits the formation of microtubules by inhibiting tubulin, a protein required for microtubule synthesis. Microtubules in the form of spindle fibers during cell division pull the DNA from the center of the mother cell into the new daughter cells. If microtubules are not formed DNA will not move into new cells. Hence new cell formation will be inhibited in the metaphase stage. Thus the correct answer is option D.
