Diffusion and Osmosis Start

TABLE OF CONTENTS Diffusion Osmosis Living Cell Osmosis Diffusion and Osmosis

DIFFUSION Dialysis Equipment Equipment Set Up Results Diffusion and Osmosis

Diffusion (Dialysis Equipment) glass dish dialysis tubing glucose test strips closures pipet Diffusion and Osmosis

dialysis tubing Starch Glucose Water Diffusion and Osmosis Initially, the dialysis tubing is filled with a super saturated glucose + starch solution Starch Glucose Water dialysis tubing continue animation Diffusion and Osmosis

The dialysis tubing membrane is selectively permeable The filled dialysis tubing is placed in a dish with a solution of iodine and water Starch Glucose Water Iodine Water The dialysis tubing membrane is selectively permeable continue animation Diffusion and Osmosis

Diffusion (Equipment Set Up) DIALYSIS TUBING starch, glucose and water iodine and water Diffusion and Osmosis

In DIFFUSION, particles travel from an area of high concentration to an area of low concentration As particles migrate through a membrane in this way, movement is described to be traveling “down a concentration gradient” Diffusion and Osmosis

When particles migrate through a selectively permeable membrane some particles are able to pass through but not others Diffusion and Osmosis

There is a GLUCOSE gradient across the membrane Starch Glucose Water Iodine Water NONE HIGH GLUCOSE molecules fit through the membrane and travel “down a concentration gradient” to the outside of the dialysis tubing … testing indicates GLUCOSE now in dish continue animation Diffusion and Osmosis

There is a IODINE gradient across the membrane HIGH Water Starch Water Glucose NONE IODINE molecules fit through the membrane and travel “down a concentration gradient” to the inside of the dialysis tubing … testing indicates IODINE now in dialysis tubing as Starch turns PURPLE continue animation Diffusion and Osmosis

There is a STARCH gradient across the membrane Iodine Water NONE HIGH Starch Water Glucose However, STARCH molecules cannot fit through the dialysis tubing membrane … water in dish is not PURPLE continue animation Diffusion and Osmosis

There is a WATER gradient across the membrane Iodine Water HIGH LOW Starch Water Glucose WATER molecules fit through the membrane and travel “down a concentration gradient” to the inside of the dialysis tubing … dialysis tubing is much fuller than before continue animation Diffusion and Osmosis

Diffusion (Results) dialysis tubing in iodine and water Diffusion and Osmosis

OSMOSIS Osmometer Equipment Equipment Set Up Results Diffusion and Osmosis

OSMOSIS (Osmometer Equipment) cup animal disc membrane bell straw rubber band cover pipet Diffusion and Osmosis

ASSEMBLING THE OSMOMETER straw inserted into narrow end of bell cup with lid bell opened at both ends selectively permeable membrane stretched across wide end of bell continue animation Diffusion and Osmosis

FILLING THE OSMOMETER Diffusion and Osmosis The position of the solution in the bell is marked The bell is filled with a super saturated lactose solution (lactose and water) The solution is dyed to make it visible in the bell The cup is filled one half full of water continue animation Diffusion and Osmosis

A super saturated solution has a relatively low water concentration because of a VERY HIGH solute concentration The osmometer solution has a large amount of lactose solute dissolved in a small amount of water Diffusion and Osmosis

The osmometer is assembled continue animation Diffusion and Osmosis

Osmosis (Equipment Set Up) fluid level super saturated lactose and water solution water Diffusion and Osmosis

OSMOMETER Diffusion and Osmosis Diffusion of water takes place through the membrane. Water is pulled from an area of high concentration (in the cup) to an area of low concentration (in the bell) continue animation Diffusion and Osmosis

OSMOMETER Diffusion and Osmosis As water diffuses through the membrane “down the gradient” from the cup into the bell the overall fluid level rises up the straw continue animation Diffusion and Osmosis

OSMOMETER Diffusion and Osmosis The membrane is selectively permeable the lactose solute particles because of their larger size are prevented from migrating through the membrane and rise up the straw along with the water continue animation Diffusion and Osmosis

Osmosis (Results) fluid level Diffusion and Osmosis osmometer solution rises up the straw water is pulled in through selectively permeable membrane Diffusion and Osmosis

LIVING CELL OSMOSIS Elodea Before NaCl Application 400x Elodea After NaCl Application 400x Elodea After NaCl Application 1000x Diffusion and Osmosis

Elodea Before NaCl Application 400x Diffusion and Osmosis

Elodea Before NaCl Application 1000x cell wall cell membrane chloroplasts continue animation Diffusion and Osmosis

The cell is initially in an isotonic solution Water within the cell keeps the cell membrane against the cell wall 100% water Chloroplasts are evenly spread throughout the cytoplasm continue animation Diffusion and Osmosis

The cell is placed in a hypertonic salt solution Elodea 1000x The cell is placed in a hypertonic salt solution continue animation Diffusion and Osmosis

When the cell is placed in a hypertonic solution there is a salt gradient across the cell wall and membrane Water goes “down the gradient” from a high water concentration inside of the cell ... 90% water 10% salt Hypertonic Solution 100% water water to a low water concentration outside of the cell continue animation Diffusion and Osmosis

Elodea After NaCl Application 400x continue animation Diffusion and Osmosis

The rigid cell wall is porous and remains intact The rigid cell wall is porous and remains intact ... but without water inside of the cell, the cell membrane is pulled from the cell wall water water Hypertonic Solution Hypertonic Solution water water Chloroplasts are draw in with the cell membrane and collect in the middle of the cell continue animation Diffusion and Osmosis

Elodea After NaCl Application 1000x cell membrane cell wall Water is pulled out of cell through the cell wall into hypertonic solution chloroplasts The cell membrane separates from the cell wall The cell membrane crenates pulling chloroplasts into a small bunch End Diffusion and Osmosis