Plasma Membrane Structure and Function PDF

The Plasma Membrane - Gateway to the Cell 1 Photograph of a Cell Membrane 2  Cell Membrane The cell membrane is flexible and allows a unicellular organism to move 3  Homeostasis (Remember this?) Balanced internal conditi...

The Plasma Membrane - Gateway to the Cell 1 Photograph of a Cell Membrane 2  Cell Membrane The cell membrane is flexible and allows a unicellular organism to move 3  Homeostasis (Remember this?) Balanced internal condition of cells Also called equilibrium Maintained by plasma membrane controlling what enters & leaves the cell 4  Functions of Plasma Membrane ✓ Protective barrier ✓ Regulate transport in & out of cell (selectively permeable) ✓ Proteins on cell membrane allow cell recognition ✓ Provide anchoring sites for filaments of cytoskeleton 5 Structure of the Cell Membrane 6  Membrane Components Phospholipids Proteins (various types Cholesterol and duties) 7  Phospholipids Make up the cell membrane Contains 2 fatty acid chains that are nonpolar Head is polar & contains a Phosphate 8 group  FLUID MOSAIC MODEL other mosaics FLUID- because individual phospholipids and proteins can move around freely within the layer, like it’s a liquid. MOSAIC- because of the pattern produced by the scattered protein molecules when the membrane is viewed from above. 9  Cell Membrane Polar heads are hydrophilic “water loving” Nonpolar tails are hydrophobic “water fearing” Makes membrane “Selective” in what crosses10 11  Cell Membrane The cell membrane is Hydrophobic made of 2 layers of molecules pass phospholipids called the lipid bilayer easily; hydrophilic DO NOT 12  Solubility Materials that are soluble in lipids can pass through the cell membrane easily 13  Cholesterol Only present in animal cells Stabilizes the membrane by reducing membrane fluidity and permeability to some smaller solutes 14 Semipermeable Membrane Small non-charged molecules move through easily. Examples: O2, and CO2 15 Semipermeable Membrane Ions, and large molecules such as glucose and amino acids do not move through the membrane on their own. They must use transport proteins 16 Assignment: - Cell Membrane Diagram Produce a hand drawn diagram (on physical paper. No digital work accepted) showing a cross section of a cell membrane that has all of the parts, structures and terms that we have gone over in class today. This is to be done on an A4 or A3 printer paper. Labels and annotations required. 17