 different classes of carbohydrates, di-saccharides first the contents, definition of di-saccharides some common di-saccharides isomers and the glycosidic bond di-saccharides students, if we see this, this is the second class of carbohydrates first class, the first class is monoseccharides second is di-saccharides and third is poly-saccharides di-saccharides name is indicating di-saccharides means sugars two, when monoseccharides combine and make a molecule that will be called as di-saccharides we will give the name of di-saccharides this is also definition when two monoseccharides are in a unit they join to each other they combine together they form a di-saccharide molecule if we talk about di-saccharides properties monoseccharides have many properties monoseccharides are sweet in taste di-saccharides are also sweet in taste but the sweetness of di-saccharides will be less because di-saccharides have more sweet di-saccharides are less sweet same is the they are already soluble in water water contains monoseccharides and di-saccharides are soluble di-saccharides are also soluble in water crystalline solids the way salt is not present in water crystalline form is present similarly di-saccharides are crystalline a common example of sugar is sugar scientifically it is called sucrose so what is sucrose? di-saccharides are the crystals they observe reducing and now reducing monoseccharides are all reducing some of di-saccharides are reducing while some of di-saccharides are not reducing a common example of reducing di-saccharides are maltose and lactose non-reducing example is sucrose di-saccharides are also present because these three are more common general formula of di-saccharides di-saccharides is cx h2o y it varies a little in case of h2o y in combination of this molecule's ratio can be different carbon's ratio can be different as you have read the formula of sucrose in sucrose if we look at the formula carbon's ratio is not the same which is present in monoseccharides some common di-saccharides example of di-saccharides sucrose is the first one lactose and maltose these three are very common apart from this di-saccharides which are allolactose apart from allolactose to remove constipation lactose is used so lactose and allolactose lactose is also a di-saccharide which is often used for constipation when it is given to the patient when it is removed sucrose is made up of gulucose and fructose subunit when we combine fructose and gulucose then sucrose is formed similarly lactose is made up of gulucose when we combine gulucose and gulucose then lactose is formed for maltose it is made up of two gulucose subunits i.e. maltose two gulucose subunits are formed whereas in sucrose and lactose along with gulucose fructose and galactose are formed isomerism there is a definition of isomerism you will read it more often isomerism is a molecule which has the same molecular formula but has a different structural formula we are mentioning this especially for di-saccharide all the di-saccharides all the di-saccharides have three sucrose, maltose and lactose all three have the same structural formula c12,H22,O11 all three have the same formula but all three have different structure if we look at the structure on the back slide here we can see the structure of sucrose is completely different in sucrose there is a six corner in lactose there are six corner subunits in maltose there are six corners but they are both gulucose even though they are different they carry the same number of atoms the molecular formula is the same so we say all the di-saccharides are isomers of each other they are isomers of each other and the molecular formula is the same glycosidic bond when two monosaccharides are combined then the new bond is called glycosidic bond glycosidic bond is a bond which is joined with the link to monosaccharide subunit since there are two monosaccharides in di-saccharide then both of them will form a glycosidic bond if we look at the glycosidic bond in the diagram we have the upper diagram which is indicated in yellow in the brown color this is the reaction of the gulucose gulucose and fructose gulucose carbon number one and fructose carbon number two which are red highlighted they will react together gulucose from carbon number one and fructose from carbon number two will be linked and this bond will be the name of the glycosidic bond and since these two subunits are connected it is called condensation reaction which is being released this is the second example of maltose in maltose there are two gulucose subunit which are linked first gulucose's carbon number one and second gulucose's carbon number four react together carbon number one and carbon number four so when you react together with one and four a glycosidic bond is formed between both the carbon both the subunits are linked and it is released during the water molecule again what we will say it is also a condensation reaction