Molecular Workbench – Diffusion

Using the Molecular Workbench software in class you will complete the following three activities.  You should copy and paste the addresses into the Molecular Workbench address bar (not to a ‘normal’ browser).

1. http://mw2.concord.org/public/part1/diffusion/diffusion.revised1.cml
2. http://mw2.concord.org/public/part1/dan/DandOpage1.cml
3. http://mw2.concord.org/public/part2/diffat/index.cml

These activities repeat some information (in a different way, which can be helpful) and then build upon one another in the following way.

1. Activity one is a general presentation of diffusion and osmosis mostly in an open space with air.
2. Activity two starts to relate this information to body systems such as the lungs and kidneys.
3. Activity three continues relating to the lungs and then shows you what is happening at the level of the cell membrane using protein channels.

You can also download the Molecular Workbench software to use at home – it is a very cool resource and it is free!  It can be downloaded from this page… http://mw.concord.org/modeler/download.html

Challenge
When you are finished the above, see if you can accomplish the following…

Overall goal:  find a way to take items of the same size and allow some of them to cross the membrane while stopping others.

1. Load the following page in Molecular Workbench… -http://mw2.concord.org/public/part1/diffusion/diffusion.membraneR2.cml-
2. In the model you should click on ‘tools – add all tools’ – you should now see many more buttons on the model toolbar – some of which may come in handy.
3. You should now click the #2 element button and add about 10 #2 elements on the left side of the ‘membrane’.
4. Click the ‘mark’ button and mark any three of the elements you just placed.
5. Your goal is to setup the model so that your ‘marked’ elements do not cross the ‘membrane’ but the other elements of the same size are able to cross.  Your ‘marked’ elements must otherwise be moving around on the left side (you can not ‘freeze’ them in place or wall them off in a corner.)
6. Once you think you have it setup correctly, be sure to save your initial state so after you run the model you don’t have to start completely over if it does not work.

hint: if you ‘right click’ on an element you can set its “properties”.
hint: you may add more items as necessary to accomplish your goal