diffusion – the movement of molecules in and out of cells
TRANSCRIPT
Diffusion – The movement of moleculesin and out of cells
Why are we made of trillions of cells Instead of 1 large cell?
As cells get larger their volume increasesand they can’t get food in and waste out effectively.
Cell size is limited by 2 factors:1. When a cell gets too big the DNA
gets overworked & fails this is called DNA overload.
2. Cells that are too large can not get food in and waste out and the cell dies.
Cells don’t’ have intestines …how do the dispose of waste?
Cell division How do cells prevent getting too large?
What regulates what diffuses in & out of cells
What do you have to gothrough to get into a cells cytoplasm?
That depends on what type of cell it is…plant or animal
What is the difference?
Cell Part_Cell Membrane_StructureMostly phospholipids plus someProtein channels & carbs.FunctionRegulate what goes in and outLocationOutside of cytoplasm_____________________________________The Cell membrane is like a Analogy Drawing __________Because it__________________________________________________________________
-= -- = Analogy: windowScreen lets air in ei oat But not the Sags. lit t 11ttIl' .aaXfre 0-cellmembrane
Molecules go through cell membranes using a process called diffusion.
Everything is made of atoms and they are always moving ex. Your desk (this is whydiffusion works)
Soooo… what is diffusion
Diffusion: The movement of molecules from areas of high concentration to areas of lower concentration.
What examples can you think of?hint: think of smells
Diffusion
Diffusion also happens with liquids.
What examples can you think of?
What would happen if you put some drops of food coloring into a beaker of water, and did not stir?
Solutions: are a mixture of 2 substances with their molecules evenly distributed
What has to happen for this to become a Solution?
What could make diffusion happen faster?
Heat speeds up diffusion
Diffusion
Relative concentrations affect the direction of diffusion.
hypertonic: high concentration
isotonic: is the same – the concentration is the same
hypotonic: low concentration
The following terms are used to compare 2 solutions.
When we refer to tonic levels it is alwaysas a comparison
Diffusion works in open areas but our cellsAre surrounded by a cell membrane…so How do molecules go in and out of the cell?
Our cell membrane are complex with lots of moving parts. This allows some things to enter while keeping other things out.
There are 2 main categories of diffusion.
Passive transportDoes not require an input of energy.
Active TransportRequires an inputor energy
What are 2 differences between passive andactive transport?
When water diffuses through a cell membrane we call it osmosis. Osmosis is the flow of water through a semi permeable membrane to areas of lower concentration.
What is the difference between osmosis and diffusion?
Is this active or passive transport?
Osmosis is the diffusion of water through a semi permeable (also called selectively permeable) membrane.
Diffusion Osmosis
Pictures of rbc and plant plasmolysis
Draw & Label : Cell Membrane
http://www.youtube.com/watch?v=n841Ab2c83Q
Equilibrium occurs when molecules are evenly distributed and there is no longer a net change. Molecules still flow in all directions.
Our bodies try to maintain homeostasisWhich means they try to maintainEquilibrium for nutrients, waste, and water, and heat.
Diffusion
Once equilibrium is reached do the Molecules continue to move?
•A suspension is a mix of water and nondissolved materials
•The contents of our digestive system is a mix of solutions and suspensions
•Nutrients and wastes are added to blood
•Homeostasis must be maintained or the system fails(you get sick & die)
We digest food and release its energy in our Mitochondria. That process makes CO2 asWaste.
What process causes •CO2 to leave our cells •go to our blood •leave our blood & go into our lungs where it is exhaled?
Potato Diffusion Mini Lab
Predict the direction of the flow of water through semi-permeable membranes when potato pieces are placed in differentsolutions.
1.Get a triple beam balance, 2 pieces of potato, 2 beakers (label one 60ml of salt water, one beaker 60ml pure [deionized]H2O2.Weigh and record the weight of each potato & which piece you place in salt water and which piece you place in pure water. 3.Predict which way water will flow according to your osmosis diffusion notes For each of the following situations1.potato into salt water.2.potato into pure water.
Potato Diffusion Mini Labmake the following chart
Weight of potato beforesoaking in solution
Weight of potato aftersoaking in solution
Distilled Water Salt WaterH2O H2O + NaCl
