Facilitated Diffusion and Active Transport
- Created by: Jasmine
- Created on: 19-02-16 16:16
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- Facilitated Diffusion and Active Transport
- Facilitated Diffusion
- Moves particles down a concentration gradient (higher to a lower concentration)
- Does not use energy
- Carrier Proteins
- Move larger molecules (glucose and amino acids)
- Can be polar molecules and ions
- 1) large molecule attaches to a carrier protein binding site in the plasma membrane
- 2) Then protein changes shape
- 3) Releases the molecule on the opposite side of the membrane where there is a lower concentration of them molecules
- Move larger molecules (glucose and amino acids)
- Channel Proteins
- Form pores in the membrane for smaller ions and polar molecules to diffuse through down a concentration gradient
- 1) Move from a high concentration of charged particles
- 2) Down the channel protein, across the plasma membrane
- 3) Into the area where there is a lower concentration of charged particles
- Moves particles down a concentration gradient (higher to a lower concentration)
- Active Transport
- Uses energy to move molecules and ions across the plasma membrane- against a concentration gradient
- Involves carrier proteins
- Same as carrier protein but energy is used (ATP) to move the solute against the concentration gradient
- Endocytosis
- Largest molecules- eg proteins, lipids and some carbohydrates
- Cell surrounds substance with a part of their plasma membrane
- Pinches off and forms a vesicle
- Processes uses energy (ATP)
- Excocytosis
- Substances eg hormones need to be released from the cell
- Vesicles pinch off from Golgi Apparatus sacs and move to the plasma membrane
- Release their contents outside the cell
- Some are not released so they go straight to the plasma membrane
- Release their contents outside the cell
- Process uses energy (ATP)
- Facilitated Diffusion
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