Notes on Chapter 6.2 & 6.3 Movement through the Membrane

Homeostasis Examples:Examples: Body temperatureBody temperature SweatingSweating ShiveringShivering DehydrationDehydration Over-hydrationOver-hydration Definition: Process by which organisms maintain a relatively stable internal environment

A. Definitions 1. Semi-permeable: allows only certain substances to pass allows only certain substances to pass Ex: cell membranes and nuclear Ex: cell membranes and nuclear membranes membranes 2. Permeable: allows all substances to pass through through II. SEMI/SELECTIVELY PERMEABLE MEMBRANE

3. Impermeable: no substances can 3. Impermeable: no substances can pass through pass through B.Live cell membranes are semi-permeable semi-permeable C. Examples of semi-permeable membranes: plastic bags, dialysis tubing membranes: plastic bags, dialysis tubing

D. Cell membrane Function Regulates the substances that enter and leave the cellRegulates the substances that enter and leave the cell

D. Cell Membrane Functions Con. ’ t A barrierA barrier ProtectionProtection SupportSupport CommunicationCommunication

E. Non-polar molecules like O 2 & CO 2 pass easily F. Sugars, ions (Na+, Cl -), large, or polar molecules more difficult

G.Lipid bilayer consists of: Phospholipids: phosphate/glycerol group + 2 fatty acids Phospholipids: phosphate/glycerol group + 2 fatty acids Cell Membrane Structure Bilayer = Double layerBilayer = Double layer ‘Head’: hydrophilic‘Head’: hydrophilic ‘Tails’: hydrophobic‘Tails’: hydrophobic Tough, flexible structureTough, flexible structure

Cell Membrane Structure 1.Marker/recognition proteins: attached to carbohydrate chains help other cells recognize their cell type 2.Receptor protein: recognizes & binds to substances outside of cell recognizes & binds to substances outside of cell 3. Enzyme: assists in chemical reactions 4. Transport protein: helps substances across membrane

H.Mosaic structure: many different elements that work together; flexible

III. Passive Transport A. Definition: Movement of molecules into and out of cell Movement of molecules into and out of cell that requires no energy that requires no energy B. Why?: Molecules are always in random motion! Molecules are always in random motion! Will always move from area of high Will always move from area of high concentration to low concentration to low

C. Types of passive transport:

1. Diffusion a. Movement of ANYTHING from high concentration to low concentration »Does not require energy! Examples:Examples: Food coloringFood coloring Tea bagTea bag PopcornPopcorn PerfumePerfume

2. Osmosis- Water Only! a. Definition: - Special kind of diffusion of water over selectively - Special kind of diffusion of water over selectively permeable membrane permeable membrane - From high concentration to low concentration - From high concentration to low concentration - Important vocab (write on side margin) - Important vocab (write on side margin) »Solute: substance in solution that is dissolved (ex: sugar or salt) substance in solution that is dissolved (ex: sugar or salt) »Solvent: substance in solution that does the dissolving (ex: water) substance in solution that does the dissolving (ex: water)

b. Examples:

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

Hypotonic Diagram Where is the most water? Which way does water go? Result? Big words Examples 92% H 2 O 97% H 2 O Outside Inside Burst, get bigger; firm “plasmoptysis”- to burst; “turgid”- get firm; “turgor pressure” :pressure inside plant cells to help stand upriight Distilled water; Contractile Vacuoles- organelle that soaks up and pumps out water

Paramecium

Hypertonic Diagram Where is the most water? Which way does water go? Result? Big words Examples 97% H 2 O 80% H 2 O Inside Outside Smaller, shrink, go limp “plasmolysis”- to wilt, shrivel, loss of pressure; “flaccid”- go limp Candy, sugar, salt on bushes/grass, gargle with salt water

Hypertonic

3. Facilitated Diffusion a. Definition: uses transport proteins to help certain molecules pass through membrane uses transport proteins to help certain molecules pass through membrane b. Ex: » Alcohol, H 2 O, small lipids » Allows in bigger molecules » No energy required! Fast & specific, high to low concentrationsFast & specific, high to low concentrations

IV. Active transport A. Definition: movement of molecules across a membrane requiring energy; from low to high concentration! movement of molecules across a membrane requiring energy; from low to high concentration! B. Why?: to maintain a certain internal environment; transport large molecules in or out of cell to maintain a certain internal environment; transport large molecules in or out of cell

Ex: Ex: Na/K Pump Na/K Pump - active transport moves 3 Na+ out of cell and - active transport moves 3 Na+ out of cell and 2 K + into cell 2 K + into cell

In active transport, materials move against concentration gradientIn active transport, materials move against concentration gradient C. Other Types: “ endocytosis ” & “ exocytosis ” “ endocytosis ” & “ exocytosis ” 1. “ Exocytosis ” a.Definition: removal of large amounts of materials/products Vesicle fuses with membrane, forcing out contents

2. Endocytosis a. Definition: process of taking in a. Definition: process of taking in materials by materials by infoldings of cell membranes infoldings of cell membranes Pocket breaks and forms vesicle in cellPocket breaks and forms vesicle in cell Large food & moleculesLarge food & molecules b. Examples: b. Examples: Pinocytosis: takes in fluidPinocytosis: takes in fluid Phagocytosis:Phagocytosis: extensions of cytoplasm surround/engulf large particles/food extensions of cytoplasm surround/engulf large particles/food (Seen in macrophages, amoeba) (Seen in macrophages, amoeba)

V. Concentration Gradient A. Explanation: 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 molecule go UP concentration gradient from LOW to HIGH concentration to HIGH concentration