Activating Prior Knowledge • Egg Osmosis • What is an egg?

• Soak a chicken egg in • A chicken egg to be more precise… 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

• Solvent

Solution Review

– the larger • Solution – Complete material {liquid} that mixture of solute and solvent dissolves the solute • Ex. Sweet tea • Water is considered the “universal” solvent • Solute – smaller substance that is dissolved by the solvent. Ex. tea & sugar

Quick Check!

I mixed Kool-Aid powder in water. Describe the mixture using the terms:

solute

,

solvent

, and

solution

.

Words to know: Hypertonic More solute Hyper means higher {more concentrated} Isotonic Solution has achieved equilibrium Hypotonic Less solute Hypo means lower less concentrated Equilibrium achieving 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

Hypertonic

High Low Hypertonic hypotonic

Hypotonic

Diffusion

• Passive • O 2 , CO 2 , H 2 O across cell membrane • Smells spreading • Movement of any molecules from a high concentration to a low concentration.

Diffusion of water across a semi permeable membrane Osmosis

Osmosis • Diffusion of water through a selectively permeable • Hypertonic membrane.

• Hypotonic • 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.

• 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 Dialysis Tubing or Plastic Bag Beaker or Clear Cup

Initial Contents Initial Solution Color Final Solution Color Initial Presence of Glucose Final Presence of Glucose

OSMOSIS DEMONSTRATION (DIALYSIS BAGS)

Interpret this experiment!

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

HYPOTONIC SOLUTION= NORMAL TURGOR PRESSURE HYPERTONIC SOLUTION= PLASMOLYSIS

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 Check Knowing 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 NO CHANGE CRENATION WILL LYSE

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

Lo w

Active Transport Low to High • Movement of materials in & out cell WITH energy

High

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 Pump (this allows for nerve function!) 3 Na+ pumped in for every 2 K+ pumped out; creates a membrane potential

Exocytosis

-

moving things out.

Moving the “Big Stuff” Molecules are moved out of the cell by vesicles that fuse with the plasma membrane.

This is how many hormones are secreted and how nerve

cells communicate with one another.

Pinocytosis

• • •

Cell forms an invagination Materials dissolve in water to be brought into cell Called “Cell Drinking”

Endocytosis – Phagocytosis Used to engulf large particles such as food, bacteria, etc. into vesicles Called “Cell Eating”

Three Forms of Transport Across the Membrane

Cellular Transport On-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 Transport ATP Cell Transport Concentration Gradient Diffusion Endocytosis Exocytosis Facilitated Diffusion Passive Transport Osmosis O 2 , CO 2 , H 2 O glucose Na+ & K+ ions