Flashcards in 3.1.1 monomers and polymers + 3.1.2 carbohydrates Deck (27)
The variety of life , both past an present , is extensive , but the biochemical basis of life is similar for all living things
Monomers are smaller units from which larger molecules are made.
Polymers are molecules made from a large number of monomers joined together
Monosaccharides , amino acids and nucleotides are examples of monomers
A condensation reaction joins two molecules together with the formation of a chemical bond and involves the elimination of a water molecule
A hydrolysis reaction breaks a chemical bond between two molecules and involved the use of a water molecule
Monosaccharides are the monomers from which larger carbohydrates are made .
Some common monosaccharides include:
A condensation reaction between two monosaccharides forms a glycosidic bond .
Disaccharides are formed by the condensation reaction of two monosaccharides
Maltose is a disaccharide formed by the condensation of two glucose molecules
Glucose + Glucose = Maltose
Sucrose is a disaccharide formed by a condensation reaction between glucose and fructose.
Lactose is a disaccharide formed by a condensation reaction between a glucose molecule and a galactose molecule.
Glucose has two isomers . Alpha glucose which has the H group on top and beta glucose which has the OH group on top
Polysaccharides are formed by the condensation of many glucose units
Glycogen is a polysaccharide composed of alpha glucose monomers
Starch is a polysaccharide formed from alpha glucose monomers
The polysaccharide Cellulose is formed by the condensation reaction of beta glucose molecules
Glucose is a primary source of energy , it is important that glucose levels in the blood are controlled "blood sugar" as this prevents diabetes
To rest if a sugar is a reducing sugar which means it can donate electrons to a chemical, then benedicts test is conducted , the procedure is putting a food to be tested in soloution and adding benedicts Reagent the contents of the test tube is then boiled in a water bath to observe potential colour change . Benedicts test for reducing sugars is semi quantitative as you can estimate the amount of reducing sugar in a sample by the degree of colour change . A strong positive result would show a red colour change while a weak positive result would show a green colour change.
All monosaccharides and most disaccharides like lactose and maltose are reducing sugars.
Sucrose while being a disaccharide is not a reducing sugar
Some sugars are non reducing to conduct a test for non reducing sugars the following steps are taken
The food being tested is of Ito soloution , hydrochloride acid is added to hydrolyse the bonds and the content of the test tube is boiled in a water bath for 5 minutes , after this sodium hydrogen carbonate is added to neutralise the acid, benedicts reagent is added and a colour change is obseved if the test indeed proves the sample
Is a non reducing sugar , this test is semi quantitative
To confirm a food contained starch a sample of the food would be placed in solution , iodine would then be added to this solution and the contents of the test tube will then be mixed , the presence of starch is indicated be a blue black colouration.
Starch is composed of monomers is alpha glucose . It is an energy store with a compact and coiled structure which is relatively branched , starch makes glycosidic bonds both (1,4) and (1,6) as the molecule is branched it can be easily hydrolysed. Stretch is a storage molecule in plants , amoylose makes up the straight part of the starch chain and amylopectin makes up the branches part . You test for starch using iodine . Starch is never found in animal cells only plant cells
Glycogen is composed of the monomer alpha glucose , it has a similar structure to starch but is more branched meaning it has more (1,6) bonds, glycogen is easily hydrolysed to realise glucose because of the heavily branched structure , it makes (1,4) , (1,6) glycosidic bonds . Glycogen is stored in animal cells in the muscles and the liver . Glycogen is insoluble so doesn't effect the water potential of cells. Hlucogen can also be found in bacteria cells