MooMooMath and Science Lecture Notes

Cell Theory and Homeostasis

• Cells are alive and maintain homeostasis by moving objects in and out.
• Key processes for movement include diffusion, facilitated diffusion, and active transport.

Diffusion

• Definition: Movement of particles from high to low concentration.
• Mechanism: Occurs through the cell membrane (a phospholipid bilayer).
  • Phospholipids have polar heads and non-polar tails.
• Characteristics:
  • Moves with the concentration gradient (high to low).
  • Does not require energy.

Facilitated Diffusion

• Definition: Diffusion with the assistance of proteins.
• Mechanism: Uses channel or carrier proteins to aid movement.
• Example: Glucose moves from high to low concentration using a carrier protein.
• Characteristics:
  • Does not require ATP.

Active Transport

• Definition: Movement of substances against the concentration gradient (low to high).
• Energy Requirement: Requires ATP.

Types of Active Transport

1. Membrane Pumps
   • Example: Sodium-potassium pump.
     • Moves sodium (Na+) and potassium (K+) against their concentration gradients.
     • Involves the attachment and detachment of phosphate groups to change protein shape.
2. Endocytosis
   • Movement of large objects into the cell by engulfing them.
   • Types:
     • Phagocytosis: Engulfing solids.
     • Pinocytosis: Engulfing liquids.
     • Receptor-mediated endocytosis: Specific molecules are captured by receptor proteins and taken into the cell.
3. Exocytosis
   • Expels objects out of the cell.
   • Objects are encased in vesicles that merge with the cell membrane to release contents.

Additional Resources

• A playlist is available for further learning on active transport.
• New math and science videos are regularly uploaded by Moving Math.