CELL MEMBRANENOTES

Notebook Pg. 56-57

Textbook: Chapter 3.3, 3.4, 3.5Pg.s 81-95

I. CELL MEMBRANEA. Purpose•Maintains homeostasis!•regulates the movement of dissolved molecules in and out of cell•Provides structure and Provides structure and supportsupport

I. CELL MEMBRANEB. StructureB. Structure•Semipermeable Lipid BilayerSemipermeable Lipid Bilayer•Hydrophilic Phosphorus Heads – love waterHydrophilic Phosphorus Heads – love water•Hydrophobic lipid tails – repel waterHydrophobic lipid tails – repel water•E (exterior) face and P (protoplasmic) face

The Fluid Mosaic Model

THE FLUID MOSAIC MODEL

Fluid Mosiac Video

• B. Structure B. Structure continuedcontinued…Write on membrane picture…Write on membrane picture

• ProteinsProteins– Integral – transport large materials in and outIntegral – transport large materials in and out– Peripheral - Many jobs including lipid digestion and signalingPeripheral - Many jobs including lipid digestion and signaling

• CarbohydratesCarbohydrates– Glycolipids - Glycolipids -  provide energy and also serve as markers for cellular recognition.– Glycoproteins – involved in immunity to diseasesGlycoproteins – involved in immunity to diseases

• Cholesterol Cholesterol – maintains integrity of membrane, keeps it from turning – maintains integrity of membrane, keeps it from turning to mush.to mush.

• CytoskeletonCytoskeleton (on P Face) - (on P Face) - shape, support, and movement.

I. CELL MEMBRANE

Other functions of membrane proteins

II. TERMS TO KNOW• SOLUTION - a

mixture of two or more substances.

• SOLUTE – The particles in the solution

• SOLVENT – Dissolves the solute

• CONCENTRATION– Refers to the

percentage of solutes in a solution.

II. TERMS TO KNOW

EquilibriumIn a solution, particles move constantly, collide with one another, and tend to spread out randomly and evenly until they reach equilibrium.

II. TERMS TO KNOW

III. PASSIVE TRANSPORT - No Energy is Required!

A. DIFFUSION• particles in a

solution move from high concentration to an area of low concentration until equilibrium is reached

Food Coloring Diffusion

• B. OSMOSIS - specifically the diffusion of water

70%

100%

If the concentration of water inside was 70% and the concentration of water outside was 95%, what would happen to size of the cell?

III. PASSIVE TRANSPORT - No Energy is Required!

Osmosis Further Explained100% Concentration(High)

0% Concentration(Low)

50% Concentration(Equilibrium)

50% Concentration(Equilibrium)

`

Is this really Osmosis???

III. PASSIVE TRANSPORTNo Energy Required

• C. Facillitated Diffusion– Helps large molecules move

through the protein channels in membrane

– Depends on random particle movements

• No energy required

IV. Active Transport• A. Protein Pumps

– Force large molecules to move in and out through protein pumps gainst a concentration gradient. (opposite direction)

– ATP Energy is required

https://Sodium Potassium Pump

IV. Active Transport

• B. Endocytosis– Cell “eats” material by infolding the cell membrane with

vesicles• Phagocytosis - cell engulfs large food particles• Pinocytosis - cell takes in liquid

https://Amoeba Endocytosis

IV. Active Transport• C. Exocytosis

– Cell releases large amounts of material

https://Paramecium Exocytosis

V. TYPES OF SOLUTION• A. HYPERTONIC SOLUTION

“Hyper” = more

– Concentration of SOLUTES is MORE

– Water concentration is LESS

– Water flows out of cell– The cell shrivels and may

die - Plasmolysis

Paramecium in Salt Water

Plant Cells in Salt Water

V. TYPES OF SOLUTION• HYPOTONIC

"HYPO" means less

• Concentration of solutes is LESS

• Water concentration is HIGH

• Water flows in • The cell swells with water,

becomes “turgid”, and dies - Cytolysis

Turgid Elodea cells

• C. IsotonicIso = equal

• Concentration is the same inside and out

• No net movement• The cell stays the

same

V. TYPES OF SOLUTION

Osmosis Summary

• Which fish is in a hypertonic solution?

• Which fish is in a hypotonic solution?

• What would have happened to Nemo (a saltwater fish with 40% solute) if he was caputured by someone who didn’t know about osmosis and put him in a freshwater tank with 0% solute?