Lecture Notes: Active Membrane Transport

Introduction

• Presenter: Dr. Mary
• Topic: Active Membrane Transport
• Previous topics included diffusion and facilitated diffusion under passive membrane transport, which requires no energy.

Active Membrane Transport

• Active transport requires energy input from the cell.
• Unlike passive transport, it moves molecules against the concentration gradient (from low to high concentration).

Types of Active Transport

1. Primary Active Transport

   • Direct use of ATP to transport molecules.
   • Example: Sodium-potassium pump, crucial in the nervous system.

2. Secondary Active Transport

   • Does not use ATP directly.
   • Relies on diffusion of one molecule to drive the transport of another.
   • Example: Sodium-glucose co-transport
     • High concentration of sodium outside the cell drives glucose transport into the cell.
     • Sodium travels down its concentration gradient while glucose "catches a ride."
   • Known as co-transport, as it involves moving two molecules across the membrane together.

Vesicular Transport

• Another form of active transport requiring ATP.

Types of Vesicular Transport

1. Exocytosis

   • Movement of materials out of the cell via vesicles.
   • Vesicles merge with the cell membrane to release contents.

2. Endocytosis

   • Movement of materials into the cell.
   • Cell membrane engulfs materials, forming a vesicle.

Conclusion

• Active membrane transport is energy-dependent and crucial for various cellular functions.
• Involves both direct energy expenditure (primary) and indirect (secondary) methods.
• Next topic: Molecular Genetics
• For questions, review the material or bring them to class for further clarification.

Notes prepared from Dr. Mary's lecture on active transport mechanisms.