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14 Cards in this Set
- Front
- Back
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Monosaccharides |
> They are sweet-tasting, soluble. > Basic formula CH2O > Examples: Glucose (alpha and beta), Galactose and Frcutose. |
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Test for reducing sugar |
1: Place 2cm3 of food into a test tube if not a solution grind it with water. 2: Add equal volume of benedicts solution. 3: Heat mixture in a warm water bath for 5 mintues. 4: If solution goes from blue to organge-brown. A reducing sugar can donate electrons to another chemical, all monosaccharides and some disaccharides eg maltose. |
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Disaccharides |
Glucose + Glucose = maltose Glucose + Fructose = sucrose Glucose + Galactose = Lactose (Glucoe all alpha) Monosaccharides are joined by glycosididc bonds in a condensation reaction which releases one molecules of water. (Hydrolysis breaks it down by adding one molecule of water) |
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Test for non reducing sugar |
Non reducing cannot donate electrons so they do not change the colour of the benedicts, so they must be hydrolysed into monosaccharides first. 1: Make sure sample is in liquid form. 2: Preform benedicts test to identify is it is non-reducing. 3: Add another 2cm3 food to a test tube and add 2cm3 of HCl and place test tube in a warm water bath for 5 mintues, the HCl will hydrolyse the carbohydrate. 4: Slowly add some sodium hydrogencarbonate and make sure the solution is alkaline. 5: Redo the benedicts test with this new solution. |
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Starch test |
1: Place 2cm3 sampkle in test tube. 2: Add 2 drops of iodine and shake. 3: Goes blue-black if starch present. |
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Starch strucutrue |
> Polysaccharides found in many parts of a plant. > Alpha glucose joined by condensation reaction into a helix. > Can be branched or unbranched, the unbranched is wound into a tight coil that makes molecule compact. > The OH group is pointed inward so hydrogen bonds point inwards. > Never found in animal cells. |
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The role of starch related to structure |
> It is insoluble and so doesn't affect the water potential so water is not drawn into cells by osmosis. > As it is large and insoluble it does not diffuse out of the cell. > It is compact so large amounts can be stored in a small place. > When hydrolysed forms alpha glucose this can be used for respiration. > The branched form has many ends which can simultaneously be acted on by enzymes meaning glucose is rapidly released. |
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Glycogen strcuture |
> Found in animal and bacteria never plants. > Glycogen structure similar to starch however shorter more branched chains. > Stored in mainly liver and muscles. > Carbohydrate is low as most the store is fat. |
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Glycogen structure related to function |
> It is insoluble and does not draw water into cells by osmosis. > Being insoluble it does not diffuse out. > It is compact so lots in a small space. > Highly branched even more than starch do ends can be acted on simultaneously by enzymes. Therefore broken down more rapidly to form monomers, this is important as animals have a higher metabolic rate therefore higher respiration rate. |
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Cellulose strcutre |
> Made up of beta gulcuose with every other beta glucose rotated 180 degrees. > Cellulose forms straight unbranched chains. > Chains run parallel to each other ad are joined by hydrogen bonds. > Major component in plant cells that provides rigidity to the plant. > Prevents cell from bursting during osmosis by exerting an inward pressure that stops an influx of water. This makes the cell turgid and push against one another. This makes non-woody parts semi rigid. This is important to keep stem and leaf in a turgid state so that they have maximum surface area for photosynthesis. |
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The role of cellulose related to the structure |
> Cellulose molecules are made up of beta glucose which forms long straight unbranched chains. > Cellulose runs parallel with hydrogen cross links so that to add collective strength. > Molecules grouped to form microfibrils to form fibres to provide more strength. |
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The role of lipids |
> Source of energy When oxidised lipid releases 2x the energy as carbohydrate per same mass and water. > Waterproofing Lipids are insoluble in water so plants and insects have waxy lipid cuticle to conserve water and animals have oily secretion form the sebaceous glands in skin. > Insulation Fats are slow conductors of heat and when stored under the skin help retain body heat. Also they act as an electrical insulator in myelin sheath around nerve cells. > Protection Fat is stored around delicate organs eg kidney. |
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Triglyceride structure |
> Made out of 3 fatty acids and one glycerol joined by an ester bond in a condensation reaction. > There are over 70 types of fatty acids, all contain carboxl COOH group and a hydrocarbon cain. |
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The structure of triglycerides related to their role |
> Triglycerides have high ratio of energy storing C-H bonds to carbon atoms so good energy source. > Triglycerides have a low mass to energy ratio so they are good storage molecule because large amounts of energy can be stored in small volumes. > Being large non-polar means they are insoluble in water. As a result their storage does not affect osmosis or water potential. > As a high ratio of hydrogen to oxygen when oxidised they make large amounts of water so good for desert animals. |
