Lecture Notes: Active Transport and Movement of Molecules

Overview

• Diffusion and Osmosis: Movement of gases and water from high to low concentration.
• Active Transport: Movement of molecules from low to high concentration, against the concentration gradient.

Active Transport

• Characteristics:
  • Requires energy (unlike diffusion and osmosis).
  • Moves substances against the concentration gradient.
  • Utilizes protein carriers in the cell membrane.

Process

• Protein Carriers:
  • Have specific binding sites for molecules.
  • Bind to molecules on the low concentration side.
  • Use energy from respiration (ATP) to move molecules.
  • Release molecules on the high concentration side.

Energy Requirement

• Comparison:
  • Diffusion: No energy needed, moves down the gradient (like sliding down).
  • Active Transport: Requires energy, moves up the gradient (like climbing a ladder).

Examples of Active Transport

• Root Hair Cells: Absorb mineral ions from the soil.
• Kidneys: Reabsorb essential substances like glucose and sodium ions.

Cellular Adaptations

• Cells involved in active transport often have numerous mitochondria to provide necessary energy.

Conclusion

• Understanding of how cells take in substances and expel waste through:
  • Diffusion: High to low concentration.
  • Osmosis: Movement of water.
  • Active Transport: Low to high concentration, requiring energy.