Cell Transport

Cell Transport

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Cell Membrane

Cell transport involves the movement of molecules across the cell membrane. All cells have a membrane; for example,

Eukaryotes: animals, plants, fungi

Prokaryotes: bacteria, archaea

The phospholipid bilayer membrane has 2 layers.

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Cell membranes are semipermeable; they allow some molecules to cross the membrane, but not others.

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Cell membrane

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Small molecules that can diffuse across the membrane without use of energy include:

• H₂O (water)

• CO₂ (carbon dioxide)

• O₂​ (oxygen)

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Passive Transport

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Video Segments

In this lesson you will watch video segments from the Amoeba Sisters' video, Cell Transport, and other short video segments. In addition you will answer questions. To play each video segment, click on the video preview.

Multiple Choice

The cell membrane is made of a

• DNA double helix

• phospholipid bilayer

• cellulose fiber framework

Multiple Select

Examples of molecules that are small enough to diffuse through the cell membrane using passive transport are (choose 3)

• water

• DNA

• oxygen

• carbon dioxide

• carbohydrate

Active transport is the use of energy to move large molecules across a cell membrane.

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Large molecules that require active transport to move in/out of a cell​ include:

• carbohydrates

• fats

• proteins​

​Active transport

Multiple Choice

Channels in the membrane for facilitated diffusion are formed by

• transport sugars

• transport lipids

• transport proteins

Multiple Choice

An important molecule that needs a transport protein to enter a cell is

• oxygen

• carbon dioxide

• glucose

Multiple Choice

The energy used for active transport in cells comes from

• ATP

• polysaccharides

• proteins

Multiple Choice

The process that can move molecules against the concentration gradient is

• active transport

• passive transport

Multiple Choice

Endocystosis is the process for moving materials

• into a cell

• out of a cell

Multiple Choice

Waste is moved out of cells through the process of

• phagocytosis

• exocytosis

• pinocytosis

Phagocytosis

Phagocytosis means "cell eating," and it is the process used by human immune cells to eat pathogens in the body.

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Unicellular organisms , such as amoebas, get their food through phagocytosis. Hear how to pronounce phagocytosis correctly in this next video.

Phagocytosis in the human immune system

In the next video you will see a white blood cell, called a neutrophil, chasing bacteria and eating them.

Multiple Choice

When the neutrophil eats bacteria, it is using

• active transport

• passive transport

Phagocytosis in unicellular organisms

In the next video you will see an amoeba eat a paramecium. The sound effects are just that -- those are not the real sounds of unicellular organisms.

Multiple Choice

The molecule that provides energy for the amoeba is

• DNA

• phospholipid

• ATP