🧬 Key Terms:

• Hypotonic: Less solute (more water)
• Hypertonic: More solute (less water)
• Isotonic: Equal solute concentration on both sides

🔍 Aquaporins: Special channel proteins that help water move faster during osmosis.

💪 Active Transport – “Push Against the Flow”

Unlike passive transport, active transport needs energy (usually in the form of ATP) to move molecules from low to high concentration.

🔋 1. Active Transport through Carrier Proteins

🔬 Definition:
Carrier proteins use ATP to push substances against their concentration gradient.

📌 Example: Sodium-potassium pump in nerve cells.

🧠 Mnemonic:
“Low to High? Use ATP to Fly!”
This reminds you that going against the gradient needs energy.

📌 Real-life example: Think of carrying water up a hill – you need energy to do that.

🍽️ 2. Endocytosis – “Eating In”

🔬 Definition:
Cell engulfs large or bulky materials by folding its membrane around them and forming a vesicle.

🔍 Types:

• Phagocytosis – “cell eating” (solids)
  • e.g., white blood cells engulfing bacteria
• Pinocytosis – “cell drinking” (liquids)
  • e.g., cell taking in nutrient-rich fluid

🧠 Mnemonic:
“Endo = Enter”
Phago = food
Pino = potion/drink

🚪 3. Exocytosis – “Sending Out”

🔬 Definition:
Cell releases waste or large molecules by fusing vesicles with the plasma membrane, spilling contents outside.

📌 Example: Hormone release from endocrine cells, waste removal.

🧠 Mnemonic:
“Exo = Exit”