Cell survival – moving materials around

Cells need nutrients to survive.

Cells sit in fluid that contains nutrients including water, oxygen, glucose and amino acids. The nutrients that are required by the cell need to cross the cell membrane.

In the same way, cellular waste must also be removed from the cell across the cell membrane and some substances must also be moved around the cell.

The outside of the cell (called the cellular or plasma membrane) is made of a phospholipid bilayer that contains fatty acids. It protects the cell and controls what can enter and exit.

Some materials, like water, can pass into the cell easily while others need assistance.

In this section, we look at how cells move materials across the cell membrane.

Transport systems

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All movement can be classified as passive or active.

• Passive transport, like diffusion, requires no energy.
• Active transport requires additional energy.

Let’s look at passive and active transport more in our next articles.