Cell Membrane and Transport Cell Membrane aka plasma

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 • •