Beginning Vocab. Words  Solute = substance being dissolved Solvent = substance that dissolves the solute (usually water) Solution = solute + solvent

Movement of Materials Into & Out of the Cell Active & Passive Transport

Define: Selectively Permeable Membrane A membrane that allows only certain materials to cross it Materials pass through pores in the membrane

Define: Selectively Permeable Membrane (continued) This membrane is a complex structure that is responsible for: separating the contents of the cell from its surroundings, for controlling the movement of materials into and out of the cell, and for interacting with the environment surrounding the cell.

Define: Selectively Permeable Membrane (continued) All living things have certain requirements they must satisfy in order to remain alive – maintain homeostasis These include exchanging gases (usually CO2 and O2), taking in water, minerals, and food, and eliminating wastes. These tasks happen at the cellular level. Molecules move easily through the cell membrane by diffusion Not all substances can easily diffuse through the membrane…

Types of Cellular Transport Passive Transport cell doesn’t use energy Diffusion Facilitated Diffusion Osmosis Active Transport cell does use energy Protein Pumps Endocytosis Exocytosis

This is gonna be hard work!! Types of Cellular Transport ___________ transport high low Weeee!!! high low This is gonna be hard work!! Passive = high to low Active = low to high ___________ transport

PASSIVE TRANSPORT

Passive Transport Movement of materials into and out of a cell No energy required Moves from [high] to [low] (Concentration gradient = difference between region of high concentration and region of low concentration (3) types: Diffusion, Facilitated diffusion, Osmosis

P.T.  Diffusion (High to Low) Diffusion: random movement of particles from an area of high concentration to an area of low concentration. (High to Low) Diffusion continues until all molecules are evenly spaced (equilibrium is reached)-Note: molecules will still move around but stay spread out. Occurs when small molecules pass through the lipid bilayer of a cell membrane http://bio.winona.edu/berg/Free.htm

Example of Diffusion

Food Coloring example

P.T.  Facilitated Diffusion B P.T.  Facilitated Diffusion 2. Facilitated diffusion: diffusion of specific particles through transport proteins found in the membrane Transport Proteins are specific – they “select” only certain molecules to cross the membrane Transports larger or charged molecules Facilitated diffusion (Channel Protein) Diffusion (Lipid Bilayer) Follows the same rules as regular, simple diffusion (high to low concentration and no energy input) BUT, uses protein carrier molecules to allow substances to move through Fac. Diffusion depends on carrier proteins embedded in the membrane to allow specific substance to pass through that might not be able to diffusion through the cell/plasma membrane Carrier Protein http://bio.winona.edu/berg/Free.htm

P.T.  Facilitated Diffusion Cellular Transport From a: Glucose molecules High Concentration Cell Membrane Low Concentration Protein channel Transport Protein Through a  Channel Proteins animations Go to Section:

Osmosis animation P.T.  Osmosis 3.Osmosis: diffusion of water through a selectively permeable membrane Water moves from [high] of water (less solute dissolved in it) to [low] of water (more solute dissolved in it) Water crosses from dilute solution (less dissolved)to concentrated solution (more dissolved) Water moves freely through pores. Solute (green) is too large to move across.

Effects of Osmosis on Life Water is so small and there is so much of it the cell can’t control it’s movement through the cell membrane.

 Lower concentration of solute (sugar) Higher of sugar Same concentration Selectively permeable mem- brane: sugar mole- cules cannot pass through pores, but water molecules can More free water molecules (higher concentration) Water molecules cluster around sugar molecules Fewer free water molecules (lower Water moves from an area of higher free water concentration to an area of lower free water concentration  Osmosis

Osmosis In this picture a red blood cell is put in a glass of distilled water (all water with no salt or sugar in it).  Because there is a higher concentration of water outside the cell, water enters the cell by OSMOSIS.  In this case too much water enters and the cell swells to the point of bursting open. 

Solutions Part 2

Solutions Any homogeneous mixture Homogeneous mixture-mixture that is evenly distributed, but can be separated Example: salt water, to separate- evaporate water and then salt is left over

Talking about solutions = Talking about “Tonicity” The amount of solutes in a solution 3 types: hypertonic, hypotonic, isotonic

Hypotonic Solution Hypotonic: The solution has a lower concentration of solutes and a higher concentration of water than inside the cell. (Low solute; High water) Result: Water moves from the solution to inside the cell): Cell Swells and bursts open (Cytolysis)!

Turgor Pressure The pressure in a plant cell due to osmosis (diffusion of H2O into the cell).

Turgor Pressure

Hypertonic Solution Hypertonic: The solution has a higher concentration of solutes and a lower concentration of water than inside the cell. (High solute; Low water) shrinks

Cytolosis A red blood cell is put in a glass of distilled water.  Water enters the cell.  In this case too much water enters and the cell swells to the point of bursting open (cytolosis). 

Plasmolysis The shrinking of the cytoplasm (cell) due to loss of H2O. Normal Plasmolysis

Isotonic Solution Isotonic: The concentration of solutes in the solution is equal to the concentration of solutes inside the cell. *same [dissolved substances] in solution as in the cell Result: Water moves equally in both directions and the cell remains same size! (Dynamic Equilibrium)

http://www.nclark.net/osmosisPocus.gif

B C A What type of solution are these cells in? Hypertonic Isotonic Hypotonic

ACTIVE TRANSPORT

Movement of materials against a concentration gradient Active Transport Movement of materials against a concentration gradient Moves from [low] to [high] Bicycle and hill example

Active Transport, type 1 Transport or Surface Proteins Substance moves across a membrane by binding to transport protein (similar to facilitated diffusion except moving from low to high conc.) Needs energy!

A.T.  Ex. of transport proteins Sodium Potassium Pumps (Active Transport using proteins) A.T.  Ex. of transport proteins Protein Pumps -transport proteins that require energy to do work Example: Sodium / Potassium Pumps are important in nerve responses. Ex of transport Protein changes shape to move molecules: this requires energy!

Endocytosis and Exocytosis Active Transport, type 2 Material enters or exits a cell by becoming enclosed in a membrane vesicle Endocytosis and Exocytosis

Examples of Membrane Bound Active Transport Endocytosis: transporting material into cell by vesicle Exocytosis: transporting material out of cell by vesicle Requires energ

Types of Active Transport 2. Endocytosis: taking bulky material into a cell Uses energy Cell membrane in-folds around food particle “cell eating” forms food vacuole & digests food This is how white blood cells eat bacteria!

Pinocytosis: small liquids are taken into cell by vesicle Endocytosis Pinocytosis: small liquids are taken into cell by vesicle Phagocytosis: solid particles ingested into cell by vesicles

Figure 7.20 Exploring Endocytosis in Animal Cells PHAGOCYTOSIS PINOCYTOSIS

Types of Active Transport 3. Exocytosis: Forces material out of cell in bulk membrane surrounding the material fuses with cell membrane Cell changes shape – requires energy EX: Hormones or wastes released from cell Endocytosis & Exocytosis animations

Exocytosis

http://programs. northlandcollege http://programs.northlandcollege.edu/biology/biology1111/animations/transport1.html