Cell (Plasma) Membrane What is it made of? Why is this a good material for a cell membrane?

Cell Membrane Phospholipid bilayer Hydrophilic head Hydrophobic tail

Cell Membrane Homeostasis – Steady state maintained by the body Selectively Permeable – Regulates what can come in and out of the cell

Selectively Permeable (6.3) CAN Small Nonpolar – (O 2 ) – (CO 2 ) – WATER CANNOT – Large (glucose) – Polar ( exception is water because its so small) – Ion (charged) Breathing

Proteins in the Cell Membrane “Fluid Mosaic Model” – Many proteins will help transport molecules across the membrane – Proteins drift freely

Membrane Proteins Embedded 1.Transport Proteins 2.Cell Recognition Proteins- sugars hang off proteins 3.Receptors Proteins- receive signals 4.Enzymes- proteins that make reactions happen

Cell Recognition Proteins Sugars hang off of proteins in the cell membrane Give us different blood types

Receptor Protein Receptor Protein- is a cell membrane protein that receives a signal

Transport

Passive Transport: Diffusion Diffusion The movement of particles HIGH concentration to LOW concentration Why? Molecules are always in random motion Ex. Perfume, food coloring, tea bag

Equilibrium- particles equally spread out

Osmosis Water ONLY! -Diffusion of water from HIGH to LOW concentration Solute: Substance in solution that is dissolved (ex. Sugar or Salt) Solvent: Substance in solution that does the dissolving ( ex. Water)

Hypotonic Environment Hypertonic Environment Isotonic Environment TONICITY

Isotonic 97% H 2 O Diagram Where is the most water? Which way does water go? Result? Big words Examples 97% H 2 O Same Inside and outside Even, same concentration overall “dynamic equilibrium” “homeostasis contact lens solution, Gatorade 97% H 2 0

Hypotonic Diagram Where is the most water? Which way does water go? Result? Big words Examples 97% H 2 O Outside Inside Burst, get bigger; firm “cytolysis”- to burst; “turgid”- get firm; “turgor pressure” :pressure inside plant cells to help stand upright - Distilled water ( 100% Water) - Plants standing upright 92 % H 2 0

Hypertonic Diagram Where is the most water? Which way does water go? Result? Big words Examples 80% Water Inside Outside Smaller, shrink, go limp “plasmolysis”- to wilt, shrivel, loss of pressure; “flaccid”- go limp 97% H 2 0

Hypertonic Red Blood Cells

Check Yourself Is the lettuce in a hypertonic isotonic hypotonic environment and why?? Poll

Passive Transport: Facilitated Diffusion Facilitated Diffusion -diffusion across a membrane through transport proteins Ex. sugars, ions, alcohol NO ENERGY: From HIGH to LOW concentration

Active Transport Movement of molecules across a membrane require energy From LOW to HIGH concentrations! Why? To maintain a certain internal environment: 1. Sodium Potassium Pump

Active Transport Exocytosis & Endocytosis 1. Exocytosis -Removal of materials -Vesicle fuses with membrane, forcing contents out

Active Transport 2. Endocytosis process of taking in materials by infolding of the cell membrane Pocket breaks and forms a vesicle in the cell Ex. Pinocytosis: take in fluid Phagocytosis: Large particle/food Amoeba

Concentration Gradient measurement of how the concentration of measurement of how the concentration of something changes from one place to another something changes from one place to another B. Passive Transport: molecules go DOWN concentration gradient from molecules go DOWN concentration gradient from HIGH to LOW concentration HIGH to LOW concentration C. Active Transport: molecule go UP concentration gradient from LOW to HIGH concentration molecule go UP concentration gradient from LOW to HIGH concentration

Review Video of Transport

Elodea Plasmolysis

Th0PuORsWY

“Egg”citing “Eggs”periment Cell membrane

Egg Lab: Osmosis

Why does a plant like hypotonic but an animal does not? ace/labbench/lab1/watpot.html ace/labbench/lab1/watpot.html