nutrients 2012

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  • 1.NUTRIENTS

2. Learning Outcomes List the chemical elements which make upcarbohydrates, fats and proteins (Pure) Describe and carry out tests for starch,reducing sugars, proteins and fats State that large molecules aresynthesised from smaller basic units State the roles of water in livingorganisms 3. 1. Carbohydrates2. Proteins3. Fats4. Water 4. Carbohydrate (Pure) Organic compounds made up ofcarbon, hydrogen and oxygen. The general formula is CmH2nOn Glucose is C6H12O6 Food sources: Rice, bread, pasta etc. 5. Types of CarbohydratesMono: 1; Di: 2; Tri: 3; Poly: many Monosaccharides (single-unit sugar) Glucose, fructose and galactose Disaccharides (double-unit sugar) Maltose, sucrose and lactose Polysaccharides (many-units of sugar) Starch, glycogen and cellulose 6. All of you are seated at your individual seats Imagine all of you are simple sugarsI am one molecule ofglucose. 7. Monosaccharides (Single sugar) Single sugar Occurrence GlucoseFound in all animalsCommon in plants, Fructosebut rare in animalsPresent in milk sugarGalactose from mammals 8. Disaccharides (Double Sugars) Double sugars Occurrence Found in sprouting Maltose grains Found in cane sugar Sucrose (common table sugar) Lactose Present in milk sugar from mammals 9. PolysaccharidesMany smaller basic units of glucosejoined together to form polysaccharides. 10. Polysaccharides (Complex Sugars)Complex sugars Occurrence Starch Storage form ofcarbohydrate in plantsGlycogen Storage form ofcarbohydrate in animals Stored mainly in liverand muscles CelluloseStructural form ofcarbohydrate in plants 11. starchglucosemaltosestarch 12. Permeability Monosaccharides are small sugarmolecules that can pass through thevisking tubing. Disaccharides and polysaccharidesare large, complex molecules thatCANNOT pass through the viskingtubing. 13. What are reducingsugars? Sugars that can produce a brick-redprecipitate when boiled with Benedictssolution are called reducing sugars. ALL monosaccharides are reducing sugars. Glucose, maltose and lactose are examples ofreducing sugars. Sucrose is NOT a reducing sugar. 14. Test for Reducing Sugars (Benedicts Test)Add an equalamount ofBenedictssolutionAbout 2cm3 oftest solution (In this case:reducingsugars e.g.glucose)Brick- Redprecipitate Heat in water bath 15. Benedicts Test for Reducing SugarStep 1: Add 2cm of Benedicts solution to2cm of sample. Shake well to mix.Step 2: Place test tube in a water bathcontaining boiling water for 5 mins.Step 3: Observe the change in colour andrecord your observations. 16. Benedicts Test for Reducing Sugar Colour Change Conclusion Remains blue Reducing sugar absentBlue to brick-redReducing sugar precipitate PRESENT 17. Benedicts Test Quantitative Test Amount of ReducingColour Change Sugar Present Traces of reducing Blue to green mixture sugarBlue to yellow or orange Moderate amount ofprecipitatereducing sugarBlue to brick-red orLarge amount oforange-red precipitate reducing sugar 18. Iodine test for StarchStep 1: Add a few drops of iodine solution to sample on a white tile(note: iodine solution = iodine + potassium iodide solution)Step 2: Observe and record your observations.Colour Change ConclusionRemains brown Starch absent Brown to blue-blackStarch colour PRESENT 19. Fats / Lipids (Pure) Organic compounds made up of carbon,hydrogen and oxygen. No general formula for fats. Found in butter, cheese,fatty meat, nuts, oil etc. 20. FatsFormed from smaller basic units of fatty acids and glycerol. 21. Fats / LipidsFatty acids + glycerolFats / Lipids 22. Test for Oil/ Fats(Ethanol/ Alcohol Emulsion Test)Add 2cm3 of Add 2cm3 ofethanol waterShake mixturethoroughly2 layers ofWhite immiscibleOil droplet emulsionliquid click 23. Ethanol Emulsion TestFor liquid food:Step 1: Add 2cm3 of ethanol to a few dropsof the sample. Shake the mixturewellfor about 5 mins.Step 2: Add 2cm3 of water to the mixtureand shake it.Step 3: Observe and record observations. Observation ConclusionSolution remains clear Fats absent Cloudy white emulsionFats PRESENT 24. For solid food:Step 1: Cut the sample into small pieces and place the pieces in a test tube.Step 2: 2cm3 of ethanol is added. Shakewell for 5 mins.Step 3: Allow the solid particles to settle.Step 4: Decant ethanol portion to another testtube containing 2cm3 of water. 25. DecantEthanol Only pour off the top layerof ethanolSolid particles 26. For solid food:Step 5: Observe and record your observations.ObservationConclusion Remains clearFats absent Cloudy white emulsion Fats PRESENT 27. Kwashiorkor 28. Proteins (Pure) Organic substances made up of carbon,hydrogen, oxygen and nitrogen Sulfur may also be present 29. Amino acidsProteins are built up from smaller basic units of amino acids 30. Amino acids to polypeptideMany amino acidslinked together to formpolypeptide. 31. Polypeptide to proteinsPolypeptideFolding of this long chain of aminoacids to give a unique three- dimensional shapeProtein is formedhttp://intro.bio.umb.edu/111-112/111F98Lect/folding.html 32. SummaryPolypeptidesAmino acidsAminoacidsPolypeptidesProteinsProteins 33. Test for Proteins(Biuret test) 1st methodAllowAdd 1%Add 1cm3 of mixture toCuSO4 dropNaOHstand forby drop 5minSample to Shake mixture Shake afterbe tested:thoroughlyeach dropin this case, Violet colourEgg white(2cm3) click 34. Biuret Test for Proteins (1st Method)Step 1: Add 1 cm3 of sodium hydroxidesolution to 2 cm3 of sample. Shake well.Step 2: Add 1% copper(II) sulfate solution, dropby drop, gently shaking after each dropStep 3: Observe and record observationsColour Change ConclusionRemains blue Proteins absentblue to violetProteins PRESENT 35. Test for Proteins(Biuret test) 2nd method AllowAdd 2cm3 ofmixture toBiuret solutionstand for 5minSample to Shake mixture wellbe tested:in this case,Violet colourEgg white(2cm3)click 36. Biuret Test for Proteins (2nd Method)Biuret solution = sodium hydroxide + copper(II) sulphate solutionStep 1: Add 2 cm3 of Biuret solution to 2 cm3 ofthe sample. Shake well.Step 2:Observe and record observations after 5minutes.Colour ChangeConclusionRemains blueProteins absentblue to violet Proteins PRESENT 37. Summary 38. WaterIn mammal, ~70% of body weight iswater 39. Functions of WaterWater is a main solvent used in thebody to dissolve substances.1. Transport of dissolved substances around body Digested food from small intestine toother parts of the body Waste products from cells to excretoryorgans for removal Hormones from glands to different partsof the body as required 40. 2. Key component of Protoplasm Digestive juices Blood Tissue fluid3. Control body temperature (cools body during evaporation of sweat)4. Required for chemical reactions to take place in. Eg. digestion!!! Prevent dehydration is NOT a function of water 41. Functions of Water in Plants1. Raw material for photosynthesis2. Maintain the turgidity of plant cells in order to keep the plant upright3. Transport of mineral salts from roots to leaves via xylem4. Transport food substances from leaves to other parts of plants via phloem 42. The End