Diffusion and osmosis
LT 6.10.4
SWABT describe and compare different
mechanisms of substance transport into and out
of cells (e.g. diffusion, osmosis, passive and
active transport)
Do gummy bears grow up?
Have you ever bought a bag of gummy
bears?
Are all gummy bears approximately
the same size?
Do gummy bears grow up?
Let’s check this out!!
Hands on activity
• Here are your gummy bears!
• Your job will be to PREDICT & OBSERVE what
happens to your gummy bears when you
merge them into water
• First, make a prediction: what does it happen
to the gummy bears if you put them in water?
• Then, record the weight of your gummy bear
Possible questions
• Does the color affect what is going to happen
to the gummy bear?
• Is the color going to dissolve?
• Will the size of gummy bear change in water?
• Make a prediction
• Discuss it with your partner
Diffusion and Osmosis
Diffusion and Osmosis
• Passive transports: diffusion (simple &
facilitated) and osmosis
• Active transport
Diffusion and Osmosis
Materials move across membranes because of
concentration differences.
Diffusion and Osmosis
Passive transport does not require energy input from
a cell.
• Molecules can move across the cell membrane
through passive transport.
• There are two types of
passive transport.
• diffusion
• osmosis
Molecules move from high to low
concentration
• Diffusion
– move from HIGH to LOW concentration
Diffusion
• Move from HIGH to LOW concentration
– passive transport
– no energy needed
diffusion
Simple Diffusion
• Move from HIGH to LOW
fat
inside cell
fat
fat
fat
fat
fat
Which way will
fat move?
LOW
HIGH
fat
outside cell
fat
fat
fat
fat
fat
fat
fat
Facilitated Diffusion
• Move from HIGH to LOW through a channel
sugar
inside cell
sugar
sugar
sugar
sugar
sugar
LOW
Which way will
sugar move?
HIGH
outside cell
sugar
sugar
sugar
sugar
sugar
sugar
sugar
Diffusion - Summarize
• Move from HIGH to LOW concentration
– directly through membrane
• simple diffusion
• no energy needed
– help through a protein channel
• facilitated diffusion (with help)
• no energy needed
HIGH
LOW
Simple vs. facilitated diffusion
simple diffusion
inside cell
lipid
facilitated diffusion
inside cell
H2O
protein channel
outside cell
outside cell
H2O
Active transport
• Cells may need molecules to move against
concentration gradient
– need to pump “uphill”
• from LOW to HIGH using energy
– protein pump
– requires energy
• ATP
ATP
Transport summary
simple
diffusion
facilitated
diffusion
active
transport
ATP
Osmosis
• Movement of WATER into a region of higher
solute concentration
diffusion of water
osmosis
Osmosis (diffusion of water)
• http://www.youtube.com/watch?v=sdiJtDRJQ
Ec
White board
• What’s the main difference between passive
and active transport?
White board
• How many types of passive transport do you
know?
White board
• Describe the facilitated passive transport
• Why is it called “facilitated” passive transport?
White board
• What are protein channels?
White board
• Describe active transport
White board
• What is osmosis?
White board
• Is osmosis a passive or active transport
mechanism?
Diffusion and Osmosis
• There are three types of solutions.
•
isotonic
•
hypertonic
•
hypotonic
Isotonic solution
Hypertonic solution
Hypotonic solution
Keeping water balance
 Cell survival depends on balancing water uptake &
water loss
freshwater
balanced
saltwater
J-TPS
Can you reverse the process?
How?