Download Active Transport Small particles such as water, carbon dioxide and

Active Transport
Small particles such as water, carbon dioxide and oxygen
diffuse freely through the cell membrane yet there are
other larger particles that the cell needs that cannot be
obtained through diffusion.
For example cells need glucose for energy. The glucose is
present in low concentrations in your blood vessels. It is in
high concentration inside your cells because your cells
constantly use the glucose. Therefore the cell uses ENERGY
to move glucose from your blood vessels into the cells. Since
glucose is a large particle, a carrier protein is needed to move
the glucose across the cell membrane.
This process of moving molecules from an area of low
concentration to an area of high concentration using a carrier
protein is known as active transport because the cell uses
ENERGY to move the molecules up the concentration
gradient.
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low
concentration
high
concentration
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