What is active transport?

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

It is essential when cells need to accumulate specific substances that are not available in sufficient concentration outside the cell.

How active transport works:

1. Against concentration gradient
Substances move from low concentration to high concentration, which is not possible through passive processes like diffusion.

2. Energy requirement (ATP)
Cells use energy released from ATP to power the transport process.

3. Use of carrier proteins
Specific membrane proteins (pumps or carriers) bind to substances and transport them across the membrane.

4. Selective and regulated process
Only specific molecules or ions are transported, ensuring precise control.

Examples:

• Uptake of mineral ions (like potassium, sodium) by plant roots

• Sodium-potassium pump in animal cells

Importance:

• Maintains ion balance in cells

• Supports nerve impulse transmission

• Helps in nutrient absorption

Difference from passive transport:

• Active transport requires energy; passive transport does not

• Moves against gradient; passive moves along gradient

In simple terms: Active transport uses energy to move substances into or out of the cell against their natural flow.