Warm-up What are the 3 components of cell theory? Balloon with vanilla

Explore---In groups A Family has 2 pets Large dog Nice and sweet But behaves poorly if no one is watching Tears up the yard…terrorizes cats Barks until everyone hates him Little Cat Everyone loves this cat…she’s purrrrfect! Your job…next slide

Your Job Come up with a solution for the pet owners The dog can’t go outside unless the owners are home The cat can come and go as she pleases Keep in mind that the dog is 2.5ft tall….the cat is about 8 inches tall Be very specific about the size and location of your solution

The Plasma (Cell) Membrane

Plasma Membrane Maintaining Balance Separates living cell from nonliving environment Allows steady flow of nutrients in an out of cell Homeostasis Maintain the cell’s environment Selective permeability Allows some molecules into the cell while keeping others out

Structure of Phospholipid Bilayer Two layers of phospholipids back to back Lipid with a phosphate group attached

Phospholipid Head is polar – interact with aqueous external environment (loves water = Hydrophilic) Tails are non polar – avoid water, afraid of water = Hydrophobic Water – soluble molecules will not pass through easily

Phospholipid Bilayer polar hydrophilic Heads nonpolar hydrophobic tails polar hydrophilic Heads

Fluid Mosaic Model Model of the plasma membrane - fluid due to flexible nature of membrane - phospholipids move like water current - proteins in membrane create pattern (mosaic) on membrane surface It’s like a fluid… It’s like a mosaic… It’s the Fluid Mosaic Model!

MosaicFluid

Other Components Cholesterol Helps stabilize phospholipids. Stops fatty acid chains from sticking together. Proteins on membrane surface aid in cell identification. Transport Proteins Span the width of the membrane Regulates which molecules may pass through the membrane.

Various Functions Outside Plasma Membrane Inside Cell Transporter Enzyme Activity Receptor Identity MarkerCell AdhesionAttach to Cytoskeleton