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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
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.
• osmosis
• diffusion
Diffusion and 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
inside cell
outside cell
Which way will fat move?
fat
fat
fat
fat
fat
fat fat
fatfat
fat
fat
fat
fat
fat
LOW
HIGH
Facilitated Diffusion• Move from HIGH to LOW through a channel
inside cell
outside cell
sugar
sugar
sugar
sugar
sugarsugar
sugarsugar
sugarsugar
sugar
Which way will sugar move?
sugar
sugar
LOW
HIGH
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
inside cell
outside cell
lipidinside cell
outside cell
H2O
simple diffusion
facilitated diffusion
H2O
protein channel
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
simplediffusion
facilitateddiffusion
activetransport
ATP
Osmosis
• Movement of WATER into a region of higher solute concentration
osmosis
diffusion of water
Osmosis (diffusion of water)
• http://www.youtube.com/watch?v=sdiJtDRJQEc
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?
• There are three types of solutions.
• isotonic
Diffusion and Osmosis
• hypotonic
• hypertonic
Isotonic solution
Hypertonic solution
Hypotonic solution
Keeping water balanceCell survival depends on balancing water
uptake & water loss
freshwater balanced saltwater
J-TPS
Can you reverse the process? How?