The Plasma Membrane - Gateway to the Cell 4/22/2017 The Plasma Membrane - Gateway to the Cell G. Podgorski, Biol. 1010

Photograph of a Cell Membrane The Plasma Membrane 4/22/2017 Photograph of a Cell Membrane G. Podgorski, Biol. 1010

The Plasma Membrane 4/22/2017 Cell Membrane The cell membrane is flexible and allows a unicellular organism to move G. Podgorski, Biol. 1010

Homeostasis Balanced internal condition of cells The Plasma Membrane 4/22/2017 Homeostasis Balanced internal condition of cells Also called equilibrium Maintained by plasma membrane controlling what enters & leaves the cell G. Podgorski, Biol. 1010

Functions of Plasma Membrane The Plasma Membrane 4/22/2017 Functions of Plasma Membrane Protective barrier Regulate transport in & out of cell (selectively permeable) Allow cell recognition Contains the cytoplasm (fluid in cell) G. Podgorski, Biol. 1010

Structure of the Cell Membrane The Plasma Membrane 4/22/2017 Structure of the Cell Membrane G. Podgorski, Biol. 1010

Membrane Components Phospholipids Proteins (peripheral and integral) The Plasma Membrane 4/22/2017 Phospholipids Proteins (peripheral and integral) Cholesterol Carbohydrates (glucose) G. Podgorski, Biol. 1010

Phospholipids Make up the cell membrane The Plasma Membrane 4/22/2017 Phospholipids Make up the cell membrane Contains 2 fatty acid chains that are nonpolar Head is polar & contains a –PO4 group & glycerol G. Podgorski, Biol. 1010

The Plasma Membrane 4/22/2017 FLUID MOSAIC MODEL 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. G. Podgorski, Biol. 1010

Cell Membrane Polar heads are hydrophilic “water loving” The Plasma Membrane Cell Membrane 4/22/2017 Polar heads are hydrophilic “water loving” Nonpolar tails are hydrophobic “water fearing” Makes membrane “selective” in what crosses G. Podgorski, Biol. 1010

The Plasma Membrane 4/22/2017 G. Podgorski, Biol. 1010

Cell Membrane Hydrophobic molecules pass easily; hydrophilic DO NOT The Plasma Membrane Cell Membrane 4/22/2017 The cell membrane is made of 2 layers of phospholipids called the lipid bilayer Hydrophobic molecules pass easily; hydrophilic DO NOT G. Podgorski, Biol. 1010

The Plasma Membrane 4/22/2017 Solubility Materials that are soluble in lipids can pass through the cell membrane easily G. Podgorski, Biol. 1010

Semipermeable Membrane The Plasma Membrane Semipermeable Membrane 4/22/2017 Small molecules and larger hydrophobic molecules move through easily. e.g. O2, CO2, H2O G. Podgorski, Biol. 1010

Semipermeable Membrane The Plasma Membrane Semipermeable Membrane 4/22/2017 Ions, hydrophilic molecules larger than water, and large molecules such as proteins do not move through the membrane on their own. G. Podgorski, Biol. 1010