Starter Why can you smell the manure when it is being spread in fields miles away? Why can you smell perfume when a girl sprays it on herself from all the way across the room? What will happen when I drop food coloring into the flask at the front of the room?

Starter Based off of your lab, why must cells be small? How might temperature and size of molecules effect diffusion across the membrane? Essay: Using all of the animal cell organelles, explain how they all work together to run as an efficient system.

Starter Finish Lab How does this lab illustrate the definition of diffusion?

The Cell Membrane Movement Across

Structure Phospholipid Bilayer – Phosphate Heads Hydrophilic – Fatty Acid Tails Hydrophobic – 2 layers, tail to tail – Embedded Proteins Gets “things” in and out of the cell

What has to get in and out? Molecules, ions and….WATER! – Water is always moving across the membrane – Movement of these substances helps cells to maintain homeostasis Stable internal environment regardless of external conditions – Cell needs to be happy!

Passive vs. Active Transport Passive – No energy needed – High Concentration  low concentration Diffusion Facilitated Diffusion Osmosis Active – Energy is needed – Low concentration  High concentration Transport protein pumps Exocytosis Endocytosis

Diffusion Movement of molecules from an area of high concentration to low concentration – Always think “high to low” Air freshener Cow Manure Depends on temperature and size of molecule diffusing – Fast – hot/small – Slow – cold/large

Osmosis The diffusion of water across a semi- permeable membrane – Semi-permeable – only certain molecules can pass Water moves across a membrane from high water concentration to an area of low water concentration – Goes to where there is more “stuff”

Osmosis *****Water always moves to where there is more “stuff” (more concentrate)

Concentration? The amount of a particular substance in a certain amount of another substance – Huh? Orange Juice – Concentrate vs. Jug – Which has more “stuff”

Concentration Solution – Uniform mixture of two or more substances Salt water Solute – Substance that is dissolved Salt Solvent – Substance doing the dissolving Water

Solutions Hypertonic – More solute outside the cell Water rushes out Cell shrinks Hypotonic – More solute inside the cell Water rushes in Cell swells

Solutions Isotonic – Same concentration of solutes/water inside and outside of the cell Water still moves in and out – It is at the same rate! Cell stays the same

Facilitated Diffusion Carrier proteins Carrier proteins – Large and not liked by the fatty acid tails – Recognize specific molecules to bring into the cell – Must be the proper molecule to enter Sugars Sugars