Thursday, September 16, 2010

High to Low That's All You Need to Know!

We continue on into the workings of the plasma membrane by taking a moment to discuss the amazing properties of water.  Because living organisms are mostly water (70 to 95%) it only makes sense to understand some of its important characteristics.

1. Water is polar meaning because of its chemical composition, there are oppositely charged regions arranged at opposing ends of the molecule.


http://www.school-for-champions.com/chemistry/polar_molecules.htm

2. Water molecules combine via the attraction of hydrogen to an oxygen on another water molecule.


http://academic.brooklyn.cuny.edu/biology/bio4fv/page/hydroge.htm





3. Water resists changes in temperature allowing living organisms time to acclimate to their environment.

http://demo.physics.uiuc.edu/lectdemo/scripts/demo_descript.idc?demoid=662
The cone on the left catches on fire more quickly than the one with a small amount of water in its base.

4. Water expands when it freezes which protects life that lives under water. 

http://mirror-us-ga1.gallery.hd.org/_exhibits/natural-science/_more2006/_more03/splash-crown-water-drop-on-blue-crazed-cracked-surface-frozen-1-AJHD.jpg


Once we knew a little more about water, we were ready to speak about the process of diffusion.  It is a passive transport that requires no energy.  

Substances move by random collisions subsequently pushing further and further apart until they are evenly distributed in their container. Particles tend to flow with the concentration gradient from high to low concentration.
http://upload.wikimedia.org/wikipedia/commons/1/1f/Dispersion.gif
Tomorrow we will continue our discussion by looking at several types of diffusion and then investigating transport that requires energy.



OSMOSIS EGGS!

Our eggs did a little shrinking last night.  Because there was a high concentration of vinegar on the inside of the egg when placed in the corn syrup, the vinegar passed over the egg's membrane and back into the beaker to try to even out the difference in concentration.  We saw the evidence of the transport when our amount of fluid remained the same or even was a little more than 200 mL.  Also our beakers of corn syrup now smelled like vinegar!

Stay tuned for tomorrow when we see what happened to our eggs that soaked in water overnight!

Bode out.

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