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Summary for QuizMonday May 30 20051213 AM TitleIdentification of Some Macromolecules Gist of ExperimentUse different tests to check for the existence of macromolecules in various substancesoIodine test checks for starch andor glycogenoBenedicts test checks for reducing sugarsoBiuret test checks for protein Notes on Underlying TheoryIntroductionThe most abundant elements in living material areoCarbonoHydrogenoOxygenoNitrogenoSulfuroPhosphorusThere are 4 major types of biological macromoleculesoCarbohydratesMonosaccharides ie glucose fructoseDisaccharides ie sucrosePolysaccharides ie starch glycogenoLipidsoProteinsoNucleic acids TestsIodine testoInformation on starchIt is a polysaccharide used by plants to store glucoseGlucose is held together with glycosidic bondsIt is a mixture of 2 different polymers amylose and amylopectinAmyloseIt is unbranched and helical molecule The glucose is joined by alpha 14 linkagesAmylopectinIt is straight and highly branchedThe glucose is joined by alpha 16 linkagesoInformation on glycogenIt is a polysaccharide used by animals to store glucoseGlucose is held together with glycosidic bondsIt is heavier than starchIt is similar to amylopectin in overall structure but is more highly branchedoHow does the test workIodine solution is usually pale yellowIt turns blueblack in the presence of starch because of the amyloseIt turns redbrown in the presence of glycogen because of the multibranched componentsBenedicts testoInformation on sugarAll sugars can exist as straight chains or in ring formThe straightchain forms are called aldose sugarsThey have a terminal aldehyde group C singlebonded to H doublebonded to OoHow does the test workBlue cupric ions Cu in Benedicts solution are reduced to cuprous ions Cu by the free aldehyde groups and we get a precipitate of cuprous oxide CuO24Cu2OH2e2CuO2H2e2The amount of cuprous oxide formed is proportional to the concentration of free aldehyde groupsThe color of the precipitate varies depending on this as well bluegreenorangeredbrownKetose sugars ie nonaldose which means nonstraight chain which means no free aldehyde group can ALSO reduce Benedicts solutionThis happens because the basic conditions of the experiment isomerize a ketose to an aldose and then the reduction happens with an aldoseBiuret testoInformation on proteinsThey are composed of amino acids which are connected by peptide bondsA peptide bond is the carboxyl group of one amino acid covalently linked to the alphaamino group of the next amino acidoHow does the test workBiuret solution is a solution of sodium hydroxide NaOH and copper sulfate CuSO4Under alkaline conditions caused by the NaOH the peptide bonds within proteins react with the Cu ions to form a purple complexSo we identify the presence of protein by looking for this purple colorSummary for QuizMonday May 30 20051213 AM TitleIsolation of Some Macromolecules Gist of ExperimentUse a variety of techniques to isolate macromolecules from a starting mixture Experiment Procedure and Justification Thereof1We start with a yeastsand mixtureaYeast cells haveiGlucan a polysaccharide in the cell wallsiiGlycogen proteins and nucleic acids in the cytoplasmbGrind the yeast to rupture the cell walls and release all this stuff1Add TCA trichloroacetic acid and continue grindingaPolysaccharides in this case glucan are soluble in TCA so they will go into solutionaBut the proteins and nucleic acids will stay suspended1Centrifuge the suspension so just the nonsand partaWhen you do this on a liquid remember the polysaccharides are suspended in the liquid with particles suspended in it remember these are the nucleic acids and proteins all the suspended stuff goes to the bottom it sediments and the liquid remains on topiThe sediment is known as the precipitate also known as pelletiiAnd the top liquid stuff is the supernatant1Now we focus just on the pellet ie the nucleic acidsproteinsaAdd NaCl to the pelletiNucleic acids are soluble in strong NaCl so they go into solutioniiBut the proteins remain in suspension1Again we centrifuge this and the proteins become the pellet and the nucleic acids are the supernatant
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