3.3) 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 the energy from respiration.
Examples of active transport include:
- uptake of glucose by epithelial cells in the villi of the small intestine (and by kidney tubules)
- uptake of ions from soil water by root hair cells in plants
Carrier proteins pick up specific molecules and take them through the cell membrane against the concentration gradient.
- Substance combines with carrier protein molecule
- Carrier transports substances across membrane using energy from respiration
- Substance released into cell
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