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Biology B3
Active transport…read more

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Active transport
· What is active transport?
[ higher ]
· Why is active transport so important?
[ Higher ]…read more

Slide 3

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Active Transport
There are two main ways in which dissolved substances
are moved into and out of cells.
Diffusion ­ the net movement of particles of a gas or solute
from an area of high concentration to an area of low
concentration (along a concentration gradient).
Osmosis ­ The net movement of water from an area of high
concentration (of water) to an area of low concentration (of
water) along a concentration gradient.
However: Sometimes substances needed by your body have to be
moved against a concentration gradient, or across a partially permeable
membrane. This is known as active transport.…read more

Slide 4

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Active transport takes place against a concentration gradient from low to high
concentration and it requires energy from respiration.
Solute Protein rotates in
molecule to membrane and
be releases solute
transported inside the cell
(using energy).
Transport protein
Protein rotates back
Solute again (often using
recognised energy).
and grabbed
by transport
Outside Inside cell…read more

Slide 5

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Active transport
Active transport allows cells to move substances from an
area of low concentration to an area of high concentration.
So substances move against the concentration gradient.
- As a result, cells can absorb ions from very dilute
- It also makes it possible for them to move substances
like sugars and ions from one place to another through
the cell membrane.…read more

Slide 6

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It takes energy for the active transport system to carry a
molecule and then return it to its original position. That
energy comes from cellular respiration.
Rate of active transport
0 Rate of respiration
So if the cell is making a lot of energy it can carry out a lot of active transport.
These cells include Root hair cells and your gut lining cells. Cells involved in a
lot of active transport usually have lots of mitochondria to provide the energy
you need.…read more

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