Warm up

• Please get out your Labs and complete the graph and questions on the back. Remember this lab is going to be turned as a product grade so try your best!

Movement through cell membranes

Diffusion

• Example: exchange of oxygen and carbon dioxide in lungs

• Molecules or ions moving from areas of higher concentration to lower concentration

• Difference in concentration is the concentration gradient

• Concentrations are equal = equilibrium

Diffusion in & out of a cell

1. the cell membrane is permeable to that substance (fat soluble such as 02 and CO2)

2. concentration gradient exists such that the substance is at a higher concentration either outside or inside the cell.

• Water molecules diffuse from higher water concentrations to lower water concentrations

• In solutions: higher concentration of solute, lower concentration of water; lower concentration of solute, higher concentration of water.

• Greater the concentration of solute (proteins), lower water concentration, greater osmotic pressure.

• Lower the concentration of solute (proteins), higher water concentration, lower osmotic pressure

Osmosis

Which way is the water moving across the membrane?

Hypertonic

• When fluid outside the cell has greater pressure than fluid inside the cell – water leaves cell

• example: salt water outside our potato is a hypotonic environment

• If you are stranded on an island why wouldn’t you want to drink the water around you?

HypotonicWhen intracellular fluid has

greater pressure than extracellular – water enters cell

example distilled water out side our potato is a hypotonic environment

• If an animal cell is over exposed it will burst.

• Example: Over hydration by drug user

Isotonic

• When inside the cell and outside the cell are the same = isotonic

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Isotonic Solution

NO NET MOVEMENT OF

H2O (equal amounts entering

& leaving)

Hypotonic Solution

Water enters cell- can cause it to burst

Hypertonic Solution

Water leaves cell until it “deflates”

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Cell in Isotonic SolutionCell in Isotonic Solution

CELLCELL

10% NaCL90% H2O

10% NaCL

90% H2O

What is the direction of water movement?The cell is at _______________.equilibrium

ENVIRONMENTENVIRONMENT

NO NET NO NET MOVEMENMOVEMENTT

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Cell in Hypotonic SolutionCell in Hypotonic Solution

CELLCELL

10% NaCL90% H2O

20% NaCL

80% H2O

What is the direction of water movement?

What is the direction of water movement?

Water moves into the cell

H2O

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Cell in Hypertonic SolutionCell in Hypertonic Solution

CELLCELL

15% NaCL85% H2O

5% NaCL95% H2O

What is the direction of water movement?

What is the direction of water movement?

ENVIRONMENTENVIRONMENT

H2O

Stop!

Pass out practice problems

Warm up

• Why don’t you want to drink salt water? What kind of environment would drinking salt water create in your body? What would happen to your cells?

• If you have 95% water and 5% solute on the inside of a cell and 80% water 20% on the out side which way will the water move?

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Three Types of Transport:

1. Passive Transport (no energy needed)

• Includes: Diffusion, Osmosis (a type of diffusion), and Facilitated Diffusion

2. Active transport (energy required)

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

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Passive Passive TransportTransport

Simple DiffusionSimple Diffusion

Doesn’t require Doesn’t require energyenergy

Molecules move Molecules move from high to low from high to low concentrationconcentration

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Passive Passive TransportTransport

Facilitated diffusion

Doesn’t require energy

Uses transport proteins to move high to low concentrationExamples: Glucose or Examples: Glucose or amino acids moving amino acids moving from blood into a from blood into a cell.cell.

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Facilitated DiffusionFacilitated Diffusion

Molecules will move through Molecules will move through the pores in Protein Channel the pores in Protein Channel

copyright cmassengale

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Active TransportActive Transport

Requires energy or ATP

Moves materials from LOW to HIGH concentration

AGAINST concentration gradient

Active transport

Active Transport• Similar to facilitated

diffusion• Differs in that particles

are moving from areas of low concentration to high concentration

• Carrier proteins also called pumps

• Examples: sugars, amino acids; sodium, potassium, calcium, and hydrogen ions

• Also absorb nutrients into cells of the intestinal walls

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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.

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How does osmosis or Diffusion play a role in the human body?

What is the main difference between Passive transport and Active transport?

What is endocytosis and exocytosis?

What happens if a red blood cell is in a hypertonic solution? Hypotonic? Isotonic?

REVIEW QUESTIONS