Explain which are the main costituents of carbohydrates and their structure

Carbohydrates, as the word says, are made up of Carbon, Oxygen and Hydrogen. They are commonly known as suggarsand are present in different forms in some kind of foods.  We can divide them in different groups: MONOSACCHARIDES: also known as "simple sugars" from greek "MONOS" : single, "SACCARON": sugar and are made up of a single unit called monomer. These monosaccharides are glucose, fructose, ribose, etc and they all have a carbonyl group C=O as an aldehyde or ketone. Moreover, according to their lenght, they can be pentose (5 carbons), exose (6 carbons), etc. We can also have longer chains of sugars when 2 monosaccharides are joined together to make a DI-saccharide (so a sugar made up of 2 monomers) such as Galactose or Saccarose (GLUCOSE + FRUCTOSE) bonded together by condensation (a chemical reaction that joins two molecules and expels a molecule of water). Using the same principal of condensation we can build very long chins that can reach 16-18 carbons. When a chain is that long we call it FATTY ACID even though the basic composition is always the same.