Download Life Science Notes – Diffusion/Osmosis/Active Transport

LS Chapter 3 section 2 Notes
Diffusion/Osmosis/Active Transport
The Cell Membrane is
selectively permeable.
Lets some substances
pass in and out of the
cell.
Movement through the Membrane
I. Functions:
 Protection
 Support
 Regulates what goes in and out of the cell (Takes
in oxygen, food, and water/eliminates wastes.)
Three Methods that
move substances in
and out of the cell are;
1. Diffusion
2. Osmosis
3. Active Transport
Diffusion moves molecules
from an area of high
concentration to an area of
low concentration.
Concentration = the
amount of substance
in a given volume.
(p.81)
Molecules are always
moving. They bump
into each other and
spread apart.
Osmosis is diffusion
of water molecules
through a selectively
permeable membrane.
This is passive
transport.
NO ENERGY IS
NEEDED
Cells cannot function
properly without
adequate water.
Active Transport is
the movement of
material through cell
membrane using
energy. If a substance
of higher
concentration is inside
the cell and the cell
needs to take in more
of that substance it
will need to use its
energy to move the
substance through the
cell membrane. The
transport protein helps
in this process.
Transport by Engulfing –
The Amoeba uses
active transport by
surrounding,
engulfing, and
wrapping around a
particle. It forms a
vacuole. This cell
uses energy in this
process.
(Phagocytosis &
pinocytosis)