hello and welcome to one of the learn videos in the Miss estri AEV biology for free lesson Series so the starting today with the introduction to biological molecules and it will cover monomers polymers and monosaccharides so we're going to start by just getting yourselves ready you'll need something to write on um for some of the questions as we go through and for making notes if at any point it's too fast or if you are going to be interactive and have a go at the questions pause as you go so the first question that you might want to pause on is thinking back to GCSE what can you remember from monomers and polymers so definition or any diagrams to represent this pause the video and have a go so you might have drawn something like this so showing these individual units under moners and a chain or bonded together under the polymers and the actual definition for a monomer is it's smaller units which can create larger molecules so it's the smaller singular or one which is what mono unit is polymers meaning many so these are made from lots of monomers and they are bonded together to create the polymer and we learn about quite a lot of monomers and polymers in biological molecules within the carbohydrates one of the key monomers will look at today is glucose and then later on within the this topic we'll be looking at starch cellulase and glycogen as examples of polymers you'll also come across proteins and the monomer amino acid and DNA and RNA structure which both have the monomer nucleotides so if we start off just by classifying the carbohydrates one thing to point out to begin with the three elements that they all contain are carbon hydrogen and oxygen we group the carbohydrates according to how many units they contain so monomers is when you have one single unit diers is two units bonded together polymers is many of those monosaccharides or monomers bonded together so we call the monomers monosaccharides the diers which are two are disaccharides and the polymers are polysaccharides and there's three examples in each of these groups you need to know for the AQA exam board for the monosaccharides it's glucose fructose and galactose so that's definitely something worth making a note of this lesson and we'll start the next lesson just quizzing you on whether you can remember those the disaccharides which will be next lesson are sucrose molos and lactose and then finally the polysaccharides that you need to know a starch cellulose and glycogen now all three of those you'll be famili familiar with from gcsc but we go into a lot more detail at a level about the structure and the function so glucose is the key monosaccharide that you need to know about and that's because it's the monosaccharide found in all three polysaccharides the molecular formula is C6 h126 which you would need to know and you also need to be able to draw glucose so key things to help you remember it is a hex en hexagen have got six sides and we have six carbons however you don't actually have six carbons with in the hexagon we have five in the hexagon and the six comes off this Bond here so we have an oxygen within the hexagen as well and we often number the carbons to make it easier to describe their position so we start from the right of the oxygen so this would be carbon one and car carbon one we have a hydrogen come off the top and hydroxy off the bottom Carbon 2 carbon 3 carbon 4 which also has a hydrogen and hydroxy carbon 5 and carbon 6 and you may notice up here we've got an alpha symbol and that's because there's actually two isomers of glucose and what an isomer is is when you have two molecules or it could be more which have the same molec formula so in this case we have glucose two versions C6 h126 so same molecular formula but their structure is different so that's what we mean by an isomer and for Alpha and beta glucose the key difference is on carbon one alpha glucose is the one we just looked at with hydrogen on top hydroxy on the bottom beta glucose one difference and that is those swap position so hydroxy on top and hydrogen on the bottom so in summary a monomer is a small unit which can create larger molecules a polymer is made from lots of monomers bonded together the carbohydrates can be classed as monosaccharides disaccharides or polysaccharides today we looked at the monosaccharides and those are the monomers of carbohydrates and the three that you need to know are glucose ose and galactose you only need to know gluc glucose in detail and that exists as two isomers Alpha and beta so you might want to click on to the disaccharides lesson next or maybe even the polysaccharides if you've covered it all um go on to practice or even testing your knowledge