Passive Transport

​Passive transport

Open Ended

What is homeostasis?

Multiple Choice

Which cell structure helps the cell maintain homeostasis?

• Mitochondria

• Cell Membrane

• Nucleus

• Ribosome

​Learn and be able to identify cellular processes and the passive transport of molecules as they cross the cell membrane

​I will...

​Explain and identify cellular processes and the passive transport of molecules as they cross the cell membrane

​We Will...

movement of molecules along a concentration gradient​

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no energy is needed​

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​Passive Transport

​What is a Concentration Gradient?

Difference in the concentration of a substance from one location to another.

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Molecules diffuse down their concentration gradient.

• a region of higher concentration to a region of lower concentration ​

Draw

Draw an arrow to show the direction that the molecules will move

Draw

Circle the area with the highest concentration of molecules

1. Diffusion

2. Facilitated Diffusion

3. Osmosis​

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3 Types of Passive Transport

Movement of a substance from a region of High concentration to a region of low concentration (natural motion, randomly in both directions)​

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​Net movement of molecules is down the concentration gradient

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Ex: O2 and CO2​

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Diffusion

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Concentration is equal = equilibrium​

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Passive process, doesn't require any extra energy​ to move the molecules

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Diffusion

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​Cells require many molecules and ions to function correctly

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​removes waste products

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​Diffusion is one method that can be used to transport these substances across the cell membrane

Diffusion​

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Gas exchange takes place

in the Lungs. Oxygen diffuses into the bloodstream & carbon

dioxide diffuses out.

Nutrients from digested

food diffuse into the cells of the small intestines and then into the bloodstream.

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​Examples of Diffusion

Molecules will continue to move around until they are equal in both areas.

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​Equilibrium = Homeostasis

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Reorder

Diffusion is the movement of molecules from an area of ______ concentration to an area of ___ concentration. Diffusion required NO ______.

• high

• low

• energy

1

2

3

• 1
• 2
• 3

​Simple Diffusion

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Properties of the cell membrane allow it to control what can enter and exit the cell.

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Molecules can pass directly through the cell membrane - simple diffusion.

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Simple Diffusion​

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Must be small enough to fit through the gaps of phospholipids.

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Middle of the cell membrane is hydrophobic.

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Only non polar molecules can pass easily through membrane

Large, polar molecules and ions cannot pass directly through the membrane - they need transport proteins to bring them through.

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This is called facilitated diffusion.

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There are two types of transport

proteins: channel & carrier proteins.

​Facilitated Diffusion

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Their interior is hydrophilic, so polar and charged molecules can pass through them.

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Water is polar but it is small.

Sometimes it can “slip” through the membrane unaided, but to transport it quickly, channel

proteins called aquaporins are needed.

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​Facilitated Diffusion

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Open Ended

Explain diffusion.

Draw

Draw a circle around simple diffusion.

Draw a triangle around facilitated diffusion.

Open Ended

What happens to the dye molecules when they are added to water?

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