What does diffuse
mean?
Diffusion - Random movement of molecules from an area of high
concentration to an area of low
concentration.
.
Concentration Gradient differences between concentrations of a
particular molecule in one area and it’s concentration in an
adjacent area
.
•
Molecules move from areas of
to
low concentration
Equilibrium What is wrong
with this picture?
•
•
high concentration
.
.
Area of evenly dispersed molecules .
No
concentration gradient
Molecules still
move randomly
concentration
.
but there is no change in
What affects the rate of diffusion:
•
•
•
•
Temperature - increase in temperature = increase diffusion
Agitation – stir or mix = increase in diffusion
Molecular weight and size – large molecule = slow diffusion
Cell size – smaller cell =
greater molecular motion
Osmosis •
WaY to remember:
Passive transport of water .
Water moves from an area of high concentration
to an area of lower concentration.
Semi-permeable – Allowing some molecules to pass through and
other molecules
not to pass through.
Exocytosis - The way cells
.
get rid of things.
Endocytosis – The way cells take things in.
• Pinocytosis cellular drinking
• Phagocytosis cellular eating
Pressure exerted on a
to
osmosis
.
What is Turgor
pressure?
•
•
plant’s cell wall
Cell becomes turgid when water flows
Cell becomes flaccid when water flows
by the central vacuole due
in
out
.
.