7.3 Movement Through the Membrane

Obvious Questions: What do we breath in? Why? What do we breath out? Why do we eat? Where does our waste come from?

Introduction to Movement Through the Membrane Selectively Permeable – Some things can pass through and others cannot oxygen Carbon dioxide water proteins food

Cell Membrane Regulates what enters and leaves the cell, and also provides protection and support

The Structure of the Cell Membrane Section 7-3 Core is lipid bi-layer Proteins form channels and pumps that help to move material into and out of cell Carbohydrates act as identification cards (immune system). Outside of cell Cell membrane Proteins Protein channel Lipid bilayer Carbohydrate chains Inside of cell (cytoplasm) :

Diffusion Movement of molecules from a high to low concentration sugar High concentration of sugar 20 gram/Liter Cell membrane Low concentration of sugar 10 grams/Liter

Osmosis – Diffusion of water Osmosis – Diffusion of water across a selectively permeable membrane. Example (oatmeal, raisin)

Osmosis Cell membrane Section 7-3 Water molecules Higher Concentration of Water Cell membrane Lower Concentration of Water Sugar molecules

Solutions add the salt Isotonic – the solution outside the cell is equal to the solution of the cytoplasm. Iso means the same. Water will move equally in both directions. No net movement across cell membrane. 90% 90% Isotonic solution

Solutions Hypertonic – the solution outside the bag is “hyper” meaning it is above strength. Hyper means high so the solution is high in solute, low in water. Water will move in both directions but more will move to an area of low concentration. This will cause the cell to lose water. H2O 90% 70% Hypertonic solution More solute = less water

Solutions Hypotonic – the solution outside the bag is “hypo” meaning below strength. Hypo means below so the solution is low in solute and high in water. Water will move in both directions but more will move inside the cell. H2O 70% 90% Hypotonic solution

Same as inside the cell. High in solute Low in water. Low in solute High in water Cell will swell Cell will not change Cell will shrink

Diffusion and Osmosis through the cell membrane (small molecules such as H2O, O2, CO2)

Facilitated Diffusion Section 7-3 Glucose molecules High Concentration Cell Membrane Low Concentration Protein channel Facilitated Diffusion – diffusion through a protein channel Larger molecules like sugars – because to large to pass through. No energy required from cell. Go to Section:

Active Transport Section 7-3 Molecule to be carried Molecule being carried Energy Low Concentration Cell Membrane Active transport is an energy requiring process moving molecules from a low concentration to a high concentration. High Concentration Low Concentration Cell Membrane High Concentration Go to Section:

Active Transport Methods Endocytosis (phagocytosis) – Taking things “into” the cell by infoldings or pockets of the cell membrane. Food, whole cells. #23 Forms a vacuole inside cell. Exocytosis – Exiting out of cell by the same process. Pocket forms with cell membrane to expel wastes. endocytosis (phagocytosis)