CIE IGCSE Biology

Revision Notes

3.3 Active Transport

What is Active Transport?

  • Active transport is the movement of particles through a cell membrane from a region of lower concentration to a region of higher concentration using energy from respiration
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Examples of Active Transport

  • Energy is needed because particles are being moved against a concentration gradient, in the opposite direction from which they would naturally move (by diffusion)
  • Examples of active transport include:
    • uptake of glucose by epithelial cells in the villi of the small intestine and by kidney tubules in the nephron
    • uptake of ions from soil water by root hair cells in plants

 

Active transport across the cell membrane, IGCSE & GCSE Biology revision notesActive transport across the cell membrane

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How Protein Molecules Move Particles

  • Active transport works by using carrier proteins embedded in the cell membrane to pick up specific molecules and take them through the cell membrane against their concentration gradient:
    1. Substance combines with carrier protein molecule in the cell membrane
    2. Carrier transports substances across membrane using energy from respiration to give them the kinetic energy needed to change shape and move the substance through the cell membrane
    3. Substance released into cell

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