Download Exchange with Environment

Exchange with
Environment
Diffusion
Osmosis
What Is Diffusion
• Particles travel from where they are CROWDED
(High Concentration) to areas of NON-CROWDED
(Low Concentration)
• Diffusion also happens in and around living cells!
• Cells do not need to use ENERGY for diffusion
Osmosis
• Cells are surrounded by/filled with fluid
• Osmosis is Diffusion of water through cell
membranes (important to life processes)
• Water is made up of particles called
MOLECULES
OSMOSIS cont.
• Pure water has high
concentration of water
molecules – add food
coloring, sugar or salt
and concentration
lowers
• Particles move from one
place to another
through a MEMBRANE.
– Semipermeable is when only
certain particles can pass
through the membrane
(PLASMA example)
Cells and Osmosis
• Red Blood Cells are surrounded by PLASMA
• Plasma is made up of water, salt, sugar and
other particles
• Concentration of these particles is kept in
balance by OSMOSIS
• If red blood cells were in pure water, water
molecules would flood into cells and cause
them to burst.
Moving Small Particles
• Small Particles like sugars cross the cell
membrane through passage ways called
CHANNELS
• Channels are made up of Proteins
• Particles travel by either ACTIVE or
PASSIVE Transport
Moving Small Particles
Cont.
• PASSIVE TRANSPORT – Movement of particles
across a cell membrane without the Use of
Energy
• ACTIVE TRANSPORT – Requires the cell to use
energy (moves stuff from low concentration to
high concentration)
Moving Large Particles
• Small particles cross cell membrane by
diffusion, passive transport and active
transport
• Large Particles move by ENDOCYTOSIS and
EXCOCYTOSIS
Endocytosis
•Active Transport is
the process when a
cell surrounds a large
particle– Like a
Protein.
•The large particles
end up surrounding a
VESICLE and bring it
into the cell.
•Vesicles are sacs
formed from pieces of
cell membrane
Exocytosis
•Large Particles leave the cell
(like Wastes)
•Cell uses Active Transport
with this process