Activating Prior Knowledge

• What is an egg?• A chicken egg to be

more precise…

• Egg Osmosis• Soak a chicken egg in

vinegar to – Remove the cell, and

– Denature the outer protein

• Then you have a big cell to experiment with!

• View and Interpret

Egg Osmosis Video

After this lesson, you should be able to

• explain the impact of water on life processes (i.e., osmosis, diffusion, SB1d).

• explain the role of the cell membrane, in maintaining homeostasis (transporting materials in/out of cell).

• Use vocabulary:– hypertonic, hypotonic, isotonic

– Passive Transport: diffusion, osmosis, facilitated diffusion

– Active Transport: sodium/potassium pump and endo/exocytosis

Solution Review• Solvent – the larger

material {liquid} that dissolves the solute

• Water is considered the “universal” solvent

• Solute – smaller substance that is dissolved by the solvent. Ex. tea & sugar

• Solution – Complete mixture of solute and solvent

• Ex. Sweet tea

Quick Check!I mixed Kool-Aid powder in water. Describe the mixture using the terms: solute, solvent, and solution.

Words to know:HypertonicMore soluteHyper means higher{more concentrated}

HypotonicLess soluteHypo means lowerless concentrated

IsotonicSolution has achievedequilibrium

Equilibriumachieving balance or equal

Diffusion Demonstration• Equal volume of cold and

warm water, each in separate clear cups

• What will happen if we drop equal amounts of food coloring in each?

• Let’s try it and observe.

• youtube

• Explain what you see.

• Lead discussion to develop diffusion definition including

– Movement of a substance

– Random molecular motion

– Kinetic energy

– Concentration gradient

– equilibrium

Diffusion• Movement of substances

from high concentration to low concentration

• Movement “down a concentration gradient”

• Due in part to random, rapid motion of molecules.

• Net Movement

• Equilibrium State

• Simple Diffusion.

• Roles in the Body

• Factors that Affect Rate:– permeability of membrane

– Size of gradient

– temperature

Passive Transport

• Movement of materials in & out of the cell without {NO} Energy

High LowHypertonic hypotonic

Hypertonic

Hypotonic

Diffusion • Passive

• O2, CO2, H2O across cell membrane

• Smells spreading

• Movement of any molecules from a high concentration to a low concentration.

OsmosisDiffusion of water

across a semi-

permeable

membrane

Osmosis• Diffusion of water through

a selectively permeable membrane.

• Movement of water – from “less salty” to “more

salty” side of membrane– from low solute

concentration to high solute concentration.

– from high water concentration to low water concentration.

• Hypertonic

• Hypotonic

• Isotonic

• In everyday life:– Preservation of food

– Eating of salty or sugary foods

– Salt on a slug

– contractile vacuoles

– turgur pressure in plants

Diffusion and Osmosis Experiment

Initial Contents

Initial Solution Color

Final Solution Color

Initial Presence of Glucose

Final Presence of Glucose

Dialysis Tubing or Plastic Bag

Beaker or Clear Cup

OSMOSIS DEMONSTRATION(DIALYSIS BAGS)

Interpret this experiment!

OSMOSIS IN PLANT CELLSWhat’s happening to the water in the cell?

HYPERTONIC SOLUTION= PLASMOLYSIS

HYPOTONIC SOLUTION= NORMAL TURGOR PRESSURE

OSMOSIS IN PLANT CELLS (Elodea)

Plasmolyzed cells

Solution Concentrations• Isotonic Solution

– When a cell is in a solution that has the same concentration of water and solutes

• Hypotonic Solution– A cell is in a solution that has a lower concentration of

solute

• Hypertonic Solution– A cell is in a solution that has a higher concentration

of solute outside of the cell

Quick CheckKnowing what we know about osmosis,

what would happen to the water in a cell in:

1. an isotonic solution?

2. a hypotonic solution?

3. a hypertonic solution?

Osmosis • Passive

• Hyper to Hypo

• Diffusion of water molecules across a membrane.

• Net movement of water toward high solute (hypertonic) side of membrane

Osmosis and Animal Cells

CRENATION WILL LYSENO CHANGE

Facilitated Diffusion• Passive• Diffusion that uses

channel proteins• Hyper to Hypo • Large molecules like

glucose

Facilitated Diffusion

• Movement from high concentration to low concentration through carrier proteins.

• Used to move ionic or large substances into or out of cells

• Passive process

• Carrier proteins are specific (will only move one substance)

• Important for moving sugars and amino acids into cells

Active Transport Low to High

• Movement of materials in & out cell WITH energy

High

Low

Quick Check!What is the main difference between active and passive transport?

Ion or Solute pump

• Active

• Protein channel

• hypotonic to hypertonic

• Ex. Na+ K + pump

• To “pump” means it uses energy (ATP)

Active Transport

• Movement of substances against a concentration gradient.– From low concentration

to high concentration.

• requires energy• pumping a substance• ATP must be hydrolyzed

to fuel this process

• Sodium-Potassium Pump

• Pumps sodium out of cells and potassium into cells.

• Important for the functioning of nerves and muscles.

• Pump is a membrane protein and an enzyme--ATPase.

Sodium-Potassium PumpSodium-Potassium Pump

(this allows for nerve (this allows for nerve function!)function!)

3 Na+ pumped in for every 2 K+ pumped out; creates a membrane

potential

Moving the “Big Stuff”Moving the “Big Stuff”

Molecules are moved out of the cell by vesicles Molecules are moved out of the cell by vesicles that fuse with the plasma membrane.that fuse with the plasma membrane.

ExocytosExocytosisis-

moving things out.

This is how many hormones are secreted and how This is how many hormones are secreted and how nerve cells communicate with one anothernerve cells communicate with one another.

PinocytosisPinocytosis

• Cell forms an Cell forms an invaginationinvagination

• Materials dissolve Materials dissolve in water to be in water to be brought into cellbrought into cell

• Called “Cell Called “Cell Drinking”Drinking”

Endocytosis – Phagocytosis Endocytosis – Phagocytosis

Used to engulf large particles such Used to engulf large particles such as food, bacteria, etc. into vesiclesas food, bacteria, etc. into vesicles

Called “Cell Eating”Called “Cell Eating”

Three Forms of Transport Across the MembraneThree Forms of Transport Across the Membrane

Cellular TransportOn-Line Tutorial

(11 slides with animated molecules moving across cell membrane; includes quiz questions along the way)

• ANOTHER ONLINE TUTORIAL

Closing Challenge – Create a “Cell Transport Concept Map” with

these words:

Active TransportATP

Cell TransportConcentration Gradient

DiffusionEndocytosisExocytosis

Facilitated DiffusionPassive Transport

OsmosisO2, CO2, H2O

glucoseNa+ & K+ ions