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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