What is active transport? Explain with examples.

Active transport is the process by which substances are moved across a cell membrane from a region of lower concentration to a region of higher concentration, against the concentration gradient, using energy in the form of ATP.

This process requires specialized proteins called carrier proteins or pumps present in the cell membrane. These proteins actively transport molecules by utilizing energy.

A common example is the sodium-potassium pump in animal cells, which maintains the balance of sodium and potassium ions inside and outside the cell. Another example is the absorption of nutrients like glucose and amino acids in the small intestine, where they are transported into cells even when their concentration is higher inside.

Active transport is essential for maintaining ion balance, nutrient uptake, and proper functioning of cells.

Thus, it is a vital mechanism that allows cells to accumulate necessary substances despite unfavorable concentration gradients.