biological molecules

monomers- small, basic molecular units polymers- large, complex molecules made up of long chains of monomers joined together

the monomers for carbohydrates are called monosaccharides glucose+glucose= maltose glucose+fructose= sucrose glucose+galactose= lactose

glucose is a hexose sugar meaning it has 6 carbons per molecule there are two isomers of glucose meaning they have the same molecular formula (C6H12O6) but different structural formulas in alpha glucose molecules, the OH is below the carbon ring. in beta glucose, the OH is above the carbon ring (the alpha is usually on top but not in this case)

a condensation reaction is where two molecules join together to form a chemical bond and a water molecule two monosaccharides join together in a condensation reaction to form a glycosidic bond and a water molecule. the product of two monosaccharides joining is called a disaccharide

a hydrolysis reaction is the breaking of a chemical bond by the addition of a water molecule. if a water molecule is added to a disaccharide, the glycosidic bond will break and you’ll have two monosaccharides

monosaccharides- the monomers of carbohydrates disaccharides- two monosaccharides joined together polysaccharides- 3 or more monosaccharides joined together

starch is a polysaccharide made up of 200-10,000 alpha glucose molecules joined with glycosidic bonds the two types of starch are amylose and amylopectin amylase is th enzyme which breaks down starch

amylose is coiled, making it compact so lots of it can be stored in a cell. this means when its hydrolysed, lots of alpha glucose will be released for energy amylose only forms 1,4 glycosidic bonds

amylopectin is highly branched meaning it can be hydrolysed by enzymes more easily and release alpha glucose for energy rapidly amylopectin forms both 1,4 and 1,6 glycosidic bonds

starch is insoluble so does not affect water potential/ osmotic balance as water is not drawn in by osmosis starch molecules are large so will not diffuse out of cells

glycogen is the storage polysaccharide found in animals. it is made of alpha glucose monosaccharides

glycogen is similar to starch but has shorter branches and is more highly branched being highly branched means it can be hydrolysed rapidly to release alpha glucose which is good because animals are more active than plants for example because of things like muscle contractions it is less compact than starch glycogen is stored in smalll granules in the muscles and liver it is insoluble and therefore does not draw water in by osmosis

cellulose is made from monomers of beta glucose. chains of beta glucose are straight and form parallel to eachother, allowing hydrogen bonds to form between the chains these individual hydrogen bonds are weak but are strong in large numbers

chains of cellulose form structures called microfibrils which provide strength and structure to the cell wall

place a drop of the (starch) solution into a depression of a spotting tile and add a drop of iodine if starch is present, the solution will go from a yellow colour to a blue/black colour

place the (glucose) solution into a test tube and add a few drops of benedicts solution. place in a hot waterbath for a few minutes if a reducing sugar is present, the solution will have gone from blue to a brick red colour if the concentration of the reducing sugar is lower, the solution may have only changed to green/yellow/orange instead of brick red

place the (sucrose) solution in a test tube and add a few drops of dilute hydrochloric acid to hydrolyse the glycosidic bonds and converts the sucrose into glucose and fructose monomers place in a hot waterbath for 5 minutes and then take it out and let it cool add a few drops of dilute sodium hydroxide solution to neutralise the acid then add a few drops of benedicts solution and place in a hot waterbath for 5 minutes the solution should go from blue to brick red if the benedicts test is positive

proteins are made up of amino acids there are 20 amino acids so there are (20)20 combinations

amino acids are made up of an amine group, a hygroxyl group, a hydrogen and an R group bonded to a carbon atom the R group is the varying group and causes the amino acids to be different

dipeptides form when two amino acids are joined together with a peptide bond polypeptides form when more than two amino acids join together with a peptide bond proteins form when two or more polypeptides join together in a condensation reaction

two amino acids join together in a condensation reaction which forms a peptide bond and a water molecule a dipeptide is the product

the primary structure is the sequence of amino acids

the secondary structure is either the coiling of the amino acid chain to form an alpha helix or its the folding of the amino acid chain to form a beta pleated sheet both of these involve hydrogen bonds

the tertiary structure is the further folding or twisting of the polypeptide chain which gives the protein its specific 3D shape form between the R groups of the polypeptide chain includes disulphide bridges, ionic bonds, hydrogen bonds and hydrophobic interactions