Structure Fits Function The Plasma Membrane 3 parts

Structure Phospholipid Bilayer – lipid (glycerol and 3 fatty acids) Lipids make up fatty acid tails and are hydrophobic (afraid of water) Phosphates are circular in shape and are hydrophilic (love water)

Structure 2. Proteins Transport proteins allow needed substances or waste material to move through the plasma membrane Chemical Markers (cell surface identity marker)– help cells to identify each other Cell Signaling (cell surface receptor) – messages from outside of cell are communicated to inside

Structure 2. Proteins Click here video on cell membrane Link to protein molecules

Structure Cholesterol: (found in animals) lipid gives stability to the membrane

Structure Fluid Mosaic Model Fluid refers to the movement of the phospholipids inside the membrane Mosaic refers to the pattern the proteins create that are moving among the phospholipids

Function Protects inside of cell, provides a boundary Plasma Membrane – job  to maintain homeostasis in the cell! Selectively Permeable - Membrane allows certain molecules to pass through while keeping others out Permeable – pass through Selective - chooses

Transport across the membrane

Cell transport Movement of material across the plasma membrane In solution Solute  particles that are dissolved (Kool aid or salt or sugar) Solvent  the substance in which the solute dissolves (water)

Concentration Amount of solute in a solution. (Think Kool-Aid) High Concentration = lots of solute Low Concentration = low amount of solute

Concentration Gradient Simply means there is a difference in concentration.

Passive Transport Requires no energy Moves with the concentration gradient across the cell membrane, move from an area of high concentration to low concentration Passive Transport keeps the cell in equilibrium

Passive Transport Three types of Passive Transport: Diffusion (oxygen and Carbon dioxide) Osmosis (water) 3. Facilitated Diffusion - transport of large molecules by a channel protein (glucose) - small molecules can go across the membrane but large ones need help

Diffusion Particles Travel HIGH Low Movement of particles from an area of high concentration to an area of low concentration Driven by: Concentration Gradient (a difference in concentration over a given space.) Equilibrium – Molecules are equal throughout. Result: Equilibrium

High concentration Concentration gradient Low concentration The greater the concentration gradient the faster the molecules move

Diffusion

Will salt diffuse into or out of the cell? Diffusion 3% salt 16% salt solution Will salt diffuse into or out of the cell?

Will salt diffuse into or out of the cell? Diffusion 3% salt 16% salt solution Will salt diffuse into or out of the cell?

OSMOSIS Diffusion of water Passive movement of water from high concentration to low concentration across a membrane

Which side needs to be diluted? So water will go to side? More water on side A because fewer particles

Water will move to side? Why?

Selectively permeable membrane 5% sugar solution 20% sugar solution 80% water 95% water Low High Selectively permeable membrane

**Cell will stay the same!! Isotonic: (ISO means equal) the concentration of dissolved material is equal inside and outside the cell. O S M O T I C S O L U T I O N S 70% Water 30% Salt Cell water **Cell will stay the same!!

Hypertonic: Concentration of dissolved material is higher outside the cell than inside. O S M O T I C S O L U T I O N S 80% Water 20% Salt 50% Water 50% Salt Cell water **Cell will Shrink.

Hypotonic: (Hypo means under or below) Concentration of dissolved material is lower outside the cell than inside the cell. O S M O T I C S O L U T I O N S 50% Water 50% Salt 90% Water 10% Salt Cell water **Cell will Swell. Helpful Reminder: Hypo (Cell Swells) is like Hippo (large hippopotamus)

Isotonic solution RBC Blood plasma No Change

Hypotonic Solution RBC Why does the RBC increase In size? Pure water

Hypertonic Solution RBC Very salty water Why has the RBC shriveled up?

C E L L O S M O S I S 3% solute 7% solute 4% solute 8% solute Hypotonic Hypertonic Isotonic Swells Shrivels Stays the same Swells, could burst Animals homeostasis in out equal 3% solute 7% solute 4% solute Plant Animal Water Flows 97% water 93% water 96% water Cell 8% solute 2% solute 4% solute 92% water 98% water 96% water Write the % of water in each cell and solution. Draw an arrow to show water movement

Turgor Pressure: water pressure in the plant cell that causes the cell membrane to press against the cell wall. It occurs in a hypotonic solution. Plasmolysis – loss of water from a plant cell, causing pressure to drop in the cell and the cell membrane will shrink. It happens in a hypertonic solution. Paramecium – contain contractile vacuoles to pump out excess water.

Active Transport Requires energy Moves against concentration gradient from low concentration to high concentration Three types of Active Transport: 1. Carrier proteins pump particles across the membrane using energy (energy, protein, and against the concentration gradient) Which way would the particles flow if it was passive transport? Which way would the particles be pumped if it was active transport? What would the result be if active transport is used? A B From side A to side B From side B to side A Unequal Concentration

Three types of Active Transport: (cont.) 2. Endocytosis- process by which materials are engulfed by the cell Endo: into cell a. Pinocytosis – cells bringing in fluids b. Phagocytosis – cells bringing in food 3. Exocytosis – process of materials leaving the cell Exo = Exit