cell transport

• Diffusion is the movement of particles from high concentration to low concentration to reach equilibrium.
• The space outside the membrane is filled with the fluid that has caused plasmolysis.
• For particles to move directly through a membrane, they must be small, non-polar, non-charged and lipid soluble.
• The rate of diffusion depends on the steepness of the concentration gradient, temperature, size of molecules, whether molecules are polar or non-polar, nature of the membrane through which they are moving, surface area, concentration gradient, and length of the diffusion pathway.
• Water, carbon dioxide and oxygen are able to easily diffuse through membranes.
• Facilitated diffusion is a process where large molecules and polar substances diffuse through channels created by pore proteins in the membrane.
• Movement of water molecules from an area of high water potential to an area of low water potential through a semi-permeable membrane to reach equilibrium is known as osmosis.
• Water potential is the energy of the water to be able to move.
• The highest value for psi is 0.
• With solutes, psi is negative.
• Hypertonic conditions have more psi inside the cell, causing water to move out of the cell.
• Isotonic conditions are when there is equilibrium.
• Hypotonic conditions have lower psi inside the cell, causing water to move into the cell.
• Muscle cells have many channel proteins to allow as much glucose to pass into the cell as possible.
• Channel proteins are specific, only letting certain substances through, and they can open and close.