Cell Membrane and Transport

Cell Membrane aka plasma membrane Regulates what enters and leaves the cell – Semi-permeable Provides structure and support Components – Lipid bilayer – double layer of phospholipids – Proteins – act as channels or pumps – Carbohydrates – chem ID cards

Cell Wall Plants, algae, fungi, bacteria Outside of cell membrane Main function - provides support and structure Composed of cellulose

Diffusion Substances move across the cell membrane – From High to Low concentration Reach equilibrium – The conc is the same throughout the system Does NOT require energy (ATP)

Osmosis The movement of water across a cell membrane Moves from High to Low conc – Until equilibrium is reached Does NOT require energy (ATP) Isotonic – Solute solution is “same strength” Hypertonic – “above strength” Hypotonic – “below strength”

When cells are placed in the following solutions

Facilitated Diffusion Protein channels Moves larger molecules: ex) glucose From High to Low conc Does NOT require energy (ATP)

Active Transport From Low to High conc Requires energy (ATP) Certain proteins act as pumps Endocytosis – taking materials into the cell by folding the cell membrane Exocytosis – vacuole fuses with cell membrane and pushes contents OUT of the cell