Moving Materials Into and Out of the Cell

Transport through the cell membrane Extracellular fluid ~ The fluid that surrounds cells. (Interstitial fluid) Intracellular fluid ~ The fluid inside of a cell. (Cytosol)

Plasma Membrane Regulates what enters and leaves the cell and also provides protection and support. Phospholipid bilayer

Plasma Membrane Semi-permeable or selectively permeable Proteins – channels and pumps that help to move material across the cell membrane. Carbohydrates – act like chemical identification cards

Solution Solvent – substance that contains substances; responsible for doing the dissolving Solute – substance dissolved in the solvent Ex: salt water Salt = solutewater = solvent

Concentration Cytoplasm contains a solution of may different substances in water Amount of substances vs amount of water Concentration gradient – drives diffusion and osmosis

Hypotonic, Hypertonic, Isotonic Hypotonic – lower concentration of solutes Hypertonic – higher concentration of solutes Isotonic – concentration is the same

Extracellular Fluid Intracellular Fluid

Extracellular Fluid Intracellular Fluid

Isotonic solution ~ The concentration of dissolved salts in the intracelluar fluid is the same as it is in the extracellular fluid. Note that normal red blood cells look a bit like Cheerios. They are round and flat with a dent in the middle.

Hypertonic solution ~ The concentration of dissolved materials is greater in the extracellular fluid than it is in the intracellular fluid. Plasmolysis ~ Cell shriveling due to a decrease in internal pressure.

Hypotonic solution ~ The concentration of dissolved materials in the intracellular fluids is greater than that in the extracellular fluid. Cytolysis ~ Cell bursting due to internal pressure.

Dynamic equilibrium The point at which concentrations of a molecule or compound is equal both inside and outside.

Passive Transport Passive transport is the movement of materials through the cell membrane that does not require the use of energy. Diffusion ~ The movement of particles from an area of high concentration to low concentration Osmosis ~ The diffusion of water through a semi- permeable membrane. In the case of cells, this will be the cell membrane.

Passive Diffusion Movement of substances is through the cell membrane from a high concentration to low concentration Osmosis is a type of passive diffusion where water molecules across the cell membrane

Facilitated Diffusion Substances cross the cell membrane through protein channels (specifically designed for that substance) No energy is used

Active Transport Movement of substances into and out of the cell using energy Protein pumps are necessary; changes in protein shapes is vital for this to occur

Active Transport Requires the use of cell energy (ATP) Endocytosis: process of taking material into the cell by folding of the cell membrane. Phagocytosis: “cell eating” Pinocytosis: cell takes in liquid from outside the cell

Active Transport Exocytosis: release of materials from the cell Membrane of the vacuole surrounding the material fuses with the cell membrane, forcing the contents out of the cell

Videos!! Plasma Membrane: zY&feature=related zY&feature=related Facilitated diffusion: Y&NR=1 Y&NR=1 Active Transport: L4