7.2 Plasma Membrane 7.4 Cellular Transport QUESTIONS OF THE DAY! What biological macromolecule makes up the plasma membrane? What is the term associated with the movement of water? What is the term associated with the movement of particles? Water can easily pass into and out of a cell. How do you think large molecules like proteins and sugars enter into and out of a cell?

7.2 Plasma Membrane Function of the Plasma Membrane Makes a barrier between internal and external environment Controls what enters and leaves the cell. (Selective permeability) Allows certain materials in and keeps others out. Small uncharged particles pass through the membrane. Large particles do not easily pass through the membrane.

7.2 Plasma Membrane Structure of the PM Phospholipid bilayer 2 layers of phospholipids arranged tail to tail. Polar heads face towards outside and inside of cell.

7.2 Plasma Membrane Other Membrane Components Proteins and carbohydrates outside the membrane signal other cells (Peripheral) Inner proteins are anchor points for cell components. (Peripheral) Integral proteins create transport channels. Cholesterol is within the lipid areas and adds fluidity

7.2 Plasma Membrane Fluid Mosaic Model – the plasma membrane moves like water and is made of many parts.

7.4 Cellular Transport QUESTION! A plasma membrane is like a fence around a community. Small animals may easily go into and out of the fence. However, large trucks with deliveries may not get through. How would these large delivery trucks get into the cell (community)?

7.4 Cellular Transport Passive Transport - High to low concentration (no energy) Facilitated Diffusion (helping) - Movement from high to low concentration. Proteins will aid particles in crossing the membrane. Osmosis (Water) Water moves from high to low concentration to reach equilibrium and does not use ATP (energy) to do it. Diffusion - Movement of particles (not water) from High concentration to low concentration to reach equilibrium (equal on both sides)

7.4 Cellular Transport QUESTION! If 100 students were crammed into this classroom, would it take energy for me to pull more students from the hallway and push them into the classroom?

7.4 Cellular Transport

7.4 Cellular Transport Active Transport - Low to high concentration (Requires Energy ATP) ***ONLY ONE THAT NEEDS ENERGY*** Particles move against the concentration gradient. Concentration: # of particles in a given space. Gradient: Difference of concentration across a membrane.

7.4 Cellular Transport 3 Types of environments where a cell exists.

7.4 Cellular Transport Isotonic – equal concentration of water and particles inside and outside the cell. No net movement of water. Hypotonic – the cell grows. More particles inside the cell than outside.The concentration of water is higher outside of the cell. Water moves into the cell Plant cells swell. The cells could pop or burst. (cytolysis) Hypertonic – the cell shrinks. More particles (high concentration) outside the cell than inside. Water moves from inside to outside the cell Plants wilt. The cells shrink and die (plasmolysis)

7.4 Cellular Transport Endocytosis – The cell eats (endo = in) Exocytosis – The cell removes waste. Particles exit. (exo=exit)

7.4 Cellular Transport CONCLUSION! All cells have a plasma membrane that regulates movement of molecules into and out of the cell. Membrane is a phospholipid bilayer that is fluid and made up of proteins, cholesterol, and carbohydrates. Diffusion is the movement of particles. Osmosis is the movement of water. Active transport requires energy in order to move particles against the concentration gradient. There are 3 environments in which cells live...isotonic, hypertonic, hypotonic. Cells utilize exocytosis to remove products and endocytosis in order to receive products

7.4 Cellular Transport TASKS! 1. Draw a plasma membrane labeling it's parts 2. How is active transport different from facilitated diffusion? 3. How is diffusion different from osmosis? 4. If a cell is dropped into a very salty solution, what would happen to the cell? Would it swell, shrink, or stay the same? Where would the water go?