Crossing Membranes
- Created by: Nicola Carter
- Created on: 12-12-12 12:06
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- Crossing Membranes
- Passive Processes
- Diffusion
- The tendency to even out is diffusion
- Gas/liquid molecules spread out from the high concentration
- Is the net movement of molecules from a region of high concentration to a region of lower concentration down a concentration graident
- No energy
- The rate of diffusion is affected by:
- Temperature
- Concentration graident
- Stirring/moving
- Surface area
- Distance
- Size of molecule
- The tendency to even out is diffusion
- Diffusion
- Active Processes
- The needs of the cell aren't always met by diffusion. Sometimes it may need more of a particular substancesin the cytoplasm than is present outside the cell or may need to move materials into or out of the cell more quickly than diffusion allows.
- Active Transport
- Refers to the movement of molecules or ion across membranes which uses ATP
- Carrier proteins
- Shape is complementryto the molecule they carry
- Carry molecules against the concentration graident
- Bulk Transport
- Endocytosis
- Which involves bringing materials into the cell
- Exoctysis
- Which involves moving material out of the cell
- Possible because membranes can easily fuse, separate and 'pinch off'
- Requires energy
- Used to move the mebranes around to form the vesicles that are needed and to move the vesicles around the cell
- Endocytosis
- Water
- Water Potential
- Is the measure of the concentration of water molecules thjat are able to diffuse.
- Solute - a substances that dissolves in a liquid
- Solvent - a liquid that dissolves substances
- Solution - a liquid containing dissolved substances
- Water Potential
- Passive Processes
- Carry larger/charged molecules through membranes
- Carrier proteins
- Shape is complementryto the molecule they carry
- Carrier proteins
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