I'm looking at sugars and I just can't get this concept.. I understand that somewhere water forms with molecules and breaks off.. but I don't see how or where...

 

Anyone have a very good and easy to comprehend website where I can read more about this?

Dehydration Synthesis - the combining of molecules to form larger ones through the removal of water. Ok. Lets say for example we want to combine 2 monosaccharides (small sugars). You know that glucose is C6H12O6. Say that we want to combine two glucose molecules. IF you want to combine both of them the way they are, they will not go together because they do NOT have any open bonds for attachment. All the bonds are already filled and no more atoms can attach to a glucose molecule anymore. Thus, in order to combine them, you have to remove a hydroxide ion (OH-) from one glucose and a hydrogen ion from the other glucose (H+). Then you can combine the two glucose molecules more easily becuase there are now open bonds that can be used to attach other molecules. The removal of OH- and H+ forms water - H2O. Just add them together - OH + H = H2O. THis is how dehydration synthesis works. Now hydrolysis is the exact opposite. If you want to break a disaccharide apart ( a disaccharide is a molecule of 2 sugars ie sucrose, lactose, maltose, fructose) you must ADD water. It is the exact opposite of dehydration synthesis.

 

If you want further clarification of the process look it up in Wikipedia.

Here's the link to the information on Wikipedia - http://en.wikipedia.org/wiki/Dehydration_synthesis

Also here's a very good website that allows you to visually see how dehydration synthesis or hydrolysis work.

http://science.nhmccd.edu/biol/dehydrat/dehydrat.html