7.3 Cell Transport cmassengale 22 Osmosis in Red Blood Cells Isotonic Hypotonic Hypertonic copyright cmassengale Please take out a separate sheet of paper •Based on the composition

7.3 Cell Transport Passive & Active

• Please turn to the page that looks like this!

Why does the cell transport materials?

• To maintain homeostasis!

Passive vs. Active

• What’s the difference?

• Energy!

ATP is Cell Energy!

• The movement of molecules across a membrane without energy input from the cell.

• ALWAYS high low concentration

• Movement of MOLECULES

• Ex: food coloring, perfume

• Movement of WATER specifically

* Movement is based on the natural kinetic energy of the particles!

In which direction will diffuse occur?

Solute molecules

Why?

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Simple Diffusion

• Requires NO energy

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DIFFUSION

Molecules move because they have a natural KINETIC ENERGY

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Diffusion of Liquids

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Diffusion through a Membrane

Cell membrane

Solute moves DOWN concentration gradient (HIGH to LOW)

Facilitated Diffusion

• What does the word “facilitate” mean?

• The diffusion of molecules across a membrane through transport PROTEINS. – Requires NO ENERGY input from the

cell

– ALWAYS moves molecules from highlow concentration • “DOWN the concentration gradient”

• REQUIRED for moving ions (have a charge), hydrophilic (“water-loving”) molecules, sugars (glucose), amino acids, and many others

OSMOSIS is a form of FACILITATED DIFFUSION

• Lipid bilayer is hydroPHOBIC

• Water has hard time passing directly through

• Special protein channels called AQUAPORINS allow water to pass through

• High Low concentration

**No energy needed

v Transport Protein

HIGH LOW

How do solutions affect cells?

• Water is always moving IN and OUT

• Equilibrium

Isotonic (Solution) Solute concentration inside the cell is equal to the outside cell.

Hypertonic (Solution) Solute concentration outside the cell is higher than the inside cell.

Hypotonic (Solution) Solute concentration outside the cell is lower than the inside cell.

*Normal *Shrinks/shrivels *Swells/bursts

No NET (overall) movement of water (in and out are equal = equilibrium)

Net movement is OUT of cell

Net movement is INTO the cell

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Cytolysis & Plasmolysis

Cytolysis Plasmolysis

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Isotonic Solution

NO NET MOVEMENT OF

H2O (equal amounts entering & leaving)

Hypotonic Solution

BURSTING

Hypertonic Solution

SHRIVELING

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Osmosis in Red Blood Cells

Isotonic Hypotonic Hypertonic copyright cmassengale

Please take out a separate sheet of paper

• Based on the composition of the cell and its environment, we can predict which way water will move.

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Cell in Isotonic Solution

CELL

10% NaCl 90% H2O

10% NaCl 90% H2O

What is the direction of water movement?

The cell is at _______________. equilibrium

ENVIRONMENT

NO NET MOVEMENT

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Cell in Hypotonic Solution

CELL

10% NaCl 90% H2O

20% NaCl 80% H2O

What is the direction of water movement?

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Cell in Hypertonic Solution

CELL

15% NaCl 85% H2O

5% NaCl 95% H2O

What is the direction of water movement?

ENVIRONMENT

• Turn to the page that looks like this

• Movement of molecules across a membrane AGAINST the concentration gradient

• Always LOW HIGH CONCENTRATION • Always requires ENERGY! • Molecules & ions usually require a

protein pump within the membrane • Larger materials require the cell

membrane to change shape • Examples: Calcium, sodium, &

potassium ion transport, Sodium-Potassium Pump, endocytosis, exocytosis

Online Resources • www.pearsonsuccessnet.com • Log in with user name and

password (directions on class website)

• Select “Content” Unit 3 Cells Chapter 7 7.3 Cell Transport (view) Activities

• Art in Motion

LOW HIGH

ATP

Process of taking in liquids or larger molecules INTO a cell by engulfing in a vesicle (requires energy) Includes pinocytosis & phagocytosis

Outside cell Outside cell Outside cell

Inside cell Inside cell Inside cell

Cell membrane

Vesicle

Vesicle breaks down when fused to lysosome

Large molecule

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Moving the “Big Stuff”

Large molecules move materials into the cell by one of three forms of endocytosis.

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Phagocytosis About to Occur

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Phagocytosis - Capture of a Yeast Cell (yellow) by Membrane Extensions of an Immune System Cell (blue)

Process of releasing materials/substances out of a cell by fusion of a vesicle with the membrane (requires energy)

Inside cell Inside cell Inside cell

Outside cell Outside cell Outside cell

Vesicle to be secreted

Vesicle transported to cell membrane

Contents released outside the cell

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Exocytosis The opposite of endocytosis is exocytosis. Large

molecules that are manufactured in the cell are released through the cell membrane.

Inside Cell Cell environment copyright cmassengale

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Exocytosis Exocytic vesicle immediately after fusion with plasma membrane.