Ch. 3 - Movement in and out of cells

Diffusion refers to the random movement of particles from a region of high concentration to low concentration. It is a passive process, which means no extra energy is required for the process. However, the process uses kinetic energy.

• Distance • Concentration Gradient • Temperature • Mass of the particle • Membrane permeability • Surface area

Osmosis refers to the random movement of solvent particles from a region of high concentration to a region of low concentration via a semi-permeable membrane. It is a passive process.

Animal cell: 1. Process - Osmosis (Cell-membrane acts as a semi-permeable membrane) 2. Water will move into the cell 3. Result - Cell swells up and finally bursts Plant cell: 1. Process - Osmosis (Cell-membrane acts as a semi-permeable membrane) 2. Water will move into the cell 3. Result - Cell swells up, but due to the protection of the cell wall, it will not burst

Animal cell: 1. Process - Osmosis (Cell-membrane acts as a semi-permeable membrane) 2. Water will move out of the cell 3. Result - Cell shrinks and becomes floppy Plant cell: 1. Process - Osmosis (Cell-membrane acts as a semi-permeable membrane) 2. Water will move out of the cell 3. Result - Cell becomes flaccid, but shape does not change due to cell wall. The cell membrane and cytoplasm shrink inward inside the rigid cell wall. When the cell membrane tears itself off the cell, this process is called plasmolysis

Active transport refers to the movement of particles from a region of low concentration to a region of high concentration, using energy from respiration. Requires the help of protein carriers As it requires energy, it is an active process

Protein carries help energy pass through by changing its shape. • The molecule from outside the cell wants to pass through • Thus the protein carrier changes shape to accomodate the molecule, and then changes shape again to push the molecule into the cell. This changing of shape requires energy.