Proteins & Active Transport (CIE IGCSE Biology)
Revision Note
Author
LáraExpertise
Biology Lead
Importance of Active Transport: Extended
- Energy is needed because particles are being moved against a concentration gradient, in the opposite direction from which they would naturally move (by diffusion)
- Active transport is vital process for the movement of molecules or ions across membranes
- Including:
- 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
Protein Carriers: Extended
- 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:
-
- Substance combines with carrier protein molecule in the cell membrane
- 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
- Substance released into cell
Carrier proteins in active transport
Exam Tip
You don't need to know anything about the phospholipid bilayer when it comes to active transport!
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