Re: ' What is the difference between a monossacharide and a dissacharide?'

Before I get to your question, here is a little background:

Carbohydrates, or sugars, make up one of the four major classes of biological molecules (the other three are proteins, nucleic acids, and lipids). They serve many crucial roles in life. Sugars are (1) the main energy source for metabolic functions, (2) a key portion of DNA and RNA, (3) structural components of cell walls, and (4) a component of some proteins.

Monosaccharides are the simplest sugars. The prefix “mono” refers to a single molecule. A good example of a monosaccharide is glucose. A disaccharide is two monosaccharides linked together to make a single molecule, hence the prefix “di”, meaning two. A good example of this is maltose, which is made up of two glucose molecules bound together. Table sugar, or sucrose, is also a disaccharide. It is made up of a glucose molecule and a fructose molecule. To extend your question a bit, there are also trisaccharides (three sugars), oligosaccharides (more than three, but generally less than 20 or so), and polysaccharides (more than 20).

I hope this answers your question!