Transcript Cell Transport - pams

Cell Transport
Selectively Permeable
• A property or characteristic of the
cell membrane.
• It can allow some materials to pass
through while keeping other
materials out.
• Ex: allows water and nutrients in;
wants to keep toxins out
Some things can pass through on their
own, some need help, some cannot
pass at all.
Diffusion
• The movement of molecules from a
higher concentration (crowded) to a
lower concentration (more space)
•
http://www.biosci.ohiou.edu/introbioslab/Bios170/diffusion/Diffusion.html
Osmosis
• The diffusion of water through a cell
membrane
• Happens when water enters the
roots of a plant
• Water also moves from a higher
concentration to a lower
concentration
• How do you lower the concentration
of water?
Osmosis
Normal RBC
RBC in pure
distilled water
Equilibrium
• A state when the molecules are
spread out evenly – but remember
the molecules are still moving.
2 Types of Transport Across
the Cell Membrane
• 1. Passive Transport
– The cell uses NO energy; the molecules
don’t need any help to cross the cell
membrane
– Diffusion
– Osmosis
2 Types of Transport Across
the Cell Membrane
• 2. Active Transport
– The cell uses energy (from ATP) to
move materials across the cell
membrane
– a transport protein may escort the
material
– Move from an area of low concentration
to high concentration – against the
normal direction of diffusion
Active Transport