How to Read a Molecule’s Skeletal Structure

glycineSince this isn’t in the textbook, here are the rules we’ll discuss and apply in class for reading the skeletal structures of molecules.

  1. Every place where lines (which represent covalent bonds) meet, there’s a carbon.
  2. Every place where lines end, there a carbon.
  3. And those carbons have the appropriate number of hydrogens bonded to them to satisfy the Octet Rule for carbon.

Try using these rules to draw out the full molecular structure of glycine (an amino acid, a kind of molecule we’ll talk about in the next part of the course) from its skeletal structure shown here. Then click on the “Continue reading” link to check your structure with a ball-and-stick depiction of glycine.  Continue reading

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Properties of Water, redux pt. 2

What property (or properties) of water or other concepts from chapter 2 can you spot in this video? What property (or properties) of life do they relate to?

Properties of Water, redux pt. 1

With the water molecule kits, figure out the following with your peers at your table:

  • What does the magnetic attraction between these plastic renditions of water molecules represent? Why are the water molecules only attracted to each other in certain ways, in certain orientations?
  • Is the molecule with the gray sphere polar or non-polar?  Hydrophilic or hydrophobic? How can you tell?
  • What do the green and blue spheres represent?
  • How does this kit show us the relative strengths of covalent, ionic and hydrogen bonds?
  • Optional: How would you depict (a) ice, (b) liquid water and (c) steam with this model kit? 

For 9/27: Biological Macromolecules

Life is just a kind of chemistry of sufficient complexity to permit reproduction and evolution.—Carl Sagan

It’s time to look at some of that complexity.

To prepare for class on Sept. 27th, please read chapter 3 in Biology by Raven, et al. You may also find it helpful to read section 2.3 in E.O Wilson’s Life on Earth or chapter 3 in OpenStax Biology. 

There will be a short quiz on this material during class.

Please use the key terms to focus your reading efforts on the essential concepts of this part of the course.