Passive Transport

Lesson Guiding Questions

1. Why is cell transport necessary?

2. What are the three types of passive transport?

The cell membrane is the border that determines what enters and exits the cell.

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Molecules must move across its border to maintain for proper cell function.​

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The movement of molecules occurs by either passive or active transport.​

Every living cell exists in a liquid environment.

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One of the most important cell process = homeostasis.

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Homeostasis is a balance between the internal physical & chemical conditions. This occurs by regulating the movement of molecules from one side of the membrane to the other.​

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Diffusion

The cytoplasm consists many different substances dissolved in water. These particles move from areas of high concentration to areas of low concentration.

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This is called diffusion.​

Module 3B: Cell Transport & Processes

Passive Transport

Diffusion

Molecules will move across the cell membrane until equilibrium is reached. Equilibrium is where concentrations are equal on both sides.

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Diffusion is the movement of random molecular movements and does not require the use of energy (ATP).

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Molecule movement that does not require energy is called passive transport.​

Module 3B: Cell Transport & Processes

Passive Transport

Facilitated Diffusion

Some molecules (such as charged ions & large molecules like glucose) cannot cross the cell membrane. Instead they use channels (proteins inside of the cell membrane) to let them pass.

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The movement of these molecules using special protein channels is known as facilitated diffusion. Although it is fast & specific, facilitated diffusion is still passive transport.

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No energy (ATP) is required for this process.​

Module 3B: Cell Transport & Processes

Passive Transport

Facilitated Diffusion: Osmosis

Water is another molecule that cannot "cross" the cell membrane without help.

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Water uses water channel proteins (called aquaporins) to move water in and out of the cell.​

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Osmosis is the diffusion of water across the cell membrane from high concentrations to low concentrations.​

Module 3B: Cell Transport & Processes

Passive Transport

​Draw this U-tube example in your notes.

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Write your summary & show it to Mr. Buie to receive credit for your notes.