Biological Molecules: Biological Macromolecules

Polymers

The word polymer just means repeating substance.  We could apply this word to a train, with a long line of repeating cars or a chain of paper clips.  Each of the repeated unit is called a monomer.  Thus, chained together they are called a polymer.  So, we are really talking about big moleculesGroups of atoms bonded together. with repeating subunits.

I have a picture of these plastic bottles because they are made from petroleum-based polymersLarge molecules made of repeating monomer units..  This picture on the right is a piece of DNA.  DNA has these subunits that each have their own identity, determined by that piece of the molecule with the letter T G A or C on it. So, subunits don’t have to be identical, but they do have to have similar structures.

Organic Compounds

The word organic just got bad.  When we think organic, usually fruits and vegetables come to mind.  However, in a chemistry class, or more specifically, a biochemistry class, the term organic means “carbon containing.”  Anything that contains carbon is an organic compound.  So, things like glucoseA simple sugar that is the main source of energy for cells., C6H12O6, and carbon dioxide CO2 would be organic.  Things like waterThe universal solvent essential for life. H2O and oxygen gas O2 would not be organic.  We get even more specific by saying that all ALLLLL organic substances fall into only four categories:  Carbohydrates, Lipids, Proteins, and Nucleic Acids. 

Dehydration and Hydrolysis

Dehydration is a word that is always known by students, but, of course, here it takes on a whole new meaning.  A dehydrationA condition in which fluid loss exceeds intake, leading to a decrease in total body water. reaction is one in which water is removed as two monomers are joined to build a polymer.  In the process of gluing the subunits together, a water molecules is removed.  Dehydration reactions are anabolic.

This suffix -lysis means “to split.”  In factA statement based on direct observation that is repeatedly confirmed., Lysol took its name from this term because that is what Lysol does to things: lysis.  Therefore the term “hydrolysis” mean using water to split something apart.  This would be a catabolic reaction as we break a polymer into two subunits.