Question

Differentiate between primary active transport and secondary active transport. Be specific with at least 100 words

Answer 1

1.Primary(direct) active transport is coupled directly with a metabolic source of energy,such as ATP hydrolysis, or absorption of light by carrier protein in halobacteria. Transport of Na ion and K ion by carrier protein, Na ion & K ion ATPase is the most common example of primary active transport.

* Virtually every animal cell maintain lower Na ion concentration and high K ion concentration than they are found in its surrounding.This balance is established and maintained by an active transport system in the plasma membrane, involves the carrier protein Na & K ATPase coupled with breakdown of ATP.

2.Secondary active (indirect) transport occurs when endergonic (uphill) transport of one solute is coupled with the exergonic(downhill) flow of a different solute that was originally pumped uphill by primary active transport.Secondary active transport is either symport or antiport, depending on whether the two solutes move in the same or opposite directions.

*A common example of secondary active transport is the symport of Na ions and glucose. The transmembrane protein Na- glucose transporter allow Na ion and glucose to enter the cell together.It present on the apical surface of the epithelium cells of the small intestine and actively transport glucose molecules into the cell from the gut.The Na ion flow down their concentration gradient while the glucose molecules are transported against their concentration gradient into the cell.