in this article we're gonna talk about polysaccharides if we think back a monosaccharide is basically one sugar unit a disaccharide has two sugar units or two monomers a polysaccharide the word poly means many so it's made up of many sugar units or many monomers the first type of polysaccharide that we're going to talk about is starch now starch is filed in plants and one of its major roles is to store energy now there's two types of plant starch that you need to be familiar with the first one is amylose and the second one is amylopectin amylose is made up of glucose monomers amylose forms a straight chain of glucose monomers so amylose would look like this it would connect all of the glucose monomers in a straight chain now the bond that connects the glucose monomers is an alpha 1-4 glycosidic bond so I'm not going to draw the entire glucose monomer but I just want to show you why it's called an alpha 1-4 glycosidic bond so this is carbon one of the first glucose unit on a left and here we have carbon four so it's a 1/4 bond now you need to be familiar with the Alpha and the beta forms of glucose in the Alpha form the O H group on carbon 1 it's faced in the downward direction the beta form of glucose has the O H group pointing up so as you can see this is the Alpha form so thus we have an alpha 1-4 glycosidic bond so amylose only has this type of glycosidic bond amylopectin is different Emmylou pectin contains in branch structures so it still has a straight chain but occasionally you'll have chains that will branch off from the main chain so that will be an example of amylopectin now let's talk about the bonds in amylopectin so the straight-chain part of amylopectin has the alpha 1-4 bond as you could see here but now the branch part of amylopectin has an alpha 1 6 bond so this is carbon one two three four five six and that's connected to carbon one of this sugar unit and it's a still an alpha bond so a milot pectin contains two types of glycosidic bonds the alpha 1-4 which is responsible for the straight chain part of amylopectin and the Alpha 1-6 glycosidic bond which is responsible for the branch in that we see in amylopectin now the next type of polysaccharide that we need to talk about is a glycogen glycogen is a polysaccharide that is made up of glucose monomers now we said that starch is found in plants a good example of starch will be potatoes but Laika j'en is the starch that is found in animals now glycogen is highly branched like amylopectin glycogen has alpha 1-4 glycosidic bonds and the alpha and six like acidic bonds which are responsible for branching next we have cellulose cellulose is a polysaccharide that is found in plants and its role is not for energy storage as in the case of starching glycogen but it serves for structural support it forms very long fibers in plants now let's talk about the bonding that's found in cellulose as we could see here this is a beta bond since it's going up and it's between carbons 1 and carbons 4 of the glucose monomers so cellulose links up the glucose units by means of beta 1-4 glycosidic bonds so that's what you need to know regarding cellulose another polysaccharide that you might be tested on is chitin chitin is similar to cellulose but it's found in insects as opposed to plants and it has a structural function as well as opposed to energy storage so that's basically it for this video so now you're familiar with the most common polysaccharides such as starch amylose amylopectin glycogen cellulose and chitin thanks for watching