Emily May
Mind Map by Emily May, updated more than 1 year ago
Emily May
Created by Emily May over 6 years ago


Key points of carbohydrates in Alevel biology

Resource summary

  1. Formulas
    1. Monosaccharide's- (CH20)n
      1. 1-Sweet tasting 2-soluble 3-atoms form a ring shape.
      2. Disaccharide's- 2(CH20)n-H2O
      3. Reactions
        1. Condensation- Joins molecules making water.
          1. Hydrolysis- Separates molecules using water.
          2. Glucose- (monosaccharide.)
            1. C6H12O6
              1. alpha-glucose.
                1. Two alpha-glucose monosaccharide's can join together to make a disaccharide.
                  1. alpha-glucose + alpha-glucose: maltose + water.
                    1. Can also go backwards in a hydrolysis reaction to form two alpha-glucose molecules from maltose and water.
                    2. Forms a glycosidic bond when the hydroxide group and oxygen are removed to form a COC bond.
                  2. beta-glucose.
                  3. Disaccharides
                    1. Sucrose
                      1. Made from glucose and fructose.
                      2. Maltose
                        1. Made from two glucose molecules.
                        2. Lactose
                          1. Made from galactose and glucose.
                        3. Tests for sugars.
                          1. Reducing sugars.
                            1. All monosaccharide's and some disaccharides are reducing sugars.
                              1. Benedict's Test
                                1. 1- Add sample to a test tube. 2- Add ten drops of benedicts reagent. 3- Heat to 90 degrees in a water baths. 4- Observe a colour change.
                                  1. If reducing sugars are present then it will change colour to a red/brown. Depending on its concentration it may even turn green, indicating there is a very low concentration.
                                2. Non-reducing sugars.
                                  1. This test is more complicated as the sugars, if present first have to be broken down by acid hydrolysis to produce the reducing sugars like monosaccharide's and some disaccharides.
                                    1. 1- Add sample to a test tube. 2- Add HCl and heat in a water bath (acid hydrolysis). 3- Leave to cool and add sodium hydrogencarbonate powder to make to solution neutral. 4- Add ten drops of benedicts reagent and observe a colour change.
                                      1. If non-reducing sugars are present then the colour will change as above.
                                        1. This test should only be completed once there is a negative result for reducing sugars.
                                      2. Polysaccharides.
                                        1. Starch.
                                          1. Test for starch is to add iodine. If starch is present it will turn brown/black, depending on concentration.
                                            1. Made of alpha-glucose; they're unbranched.
                                              1. They're a good energy store and respiratory substrate found in grains in potato tubers, seeds and stoma of chloroplasts.
                                                1. Properties: Compact, too big to pass through membranes, insoluble- osmotically inactive, many glucose molecules, arranged in a helix.
                                                2. Glycogen
                                                  1. Made of alpha-glucose and found in humans in the liver and muscles. Also found in fungi and bacteria.
                                                    1. They're branched and act as a quick energy release stores and regulate blood glucose levels.
                                                      1. Properties: branched, insoluble and tightly coiled.
                                                      2. Cellulose.
                                                        1. Properties: Mechanically strong, inverted arrangement of successive glucose molecules forming hydrogen bonds, tightly crossed-linked to form micro fibrils and fibres, interwoven, gaps allow permeability.
                                                          1. Made of beta-glucose; they're unbranched.
                                                            1. They're good at maintaining cell wall turgidity- leaves held in place and stem flexible but firm in the wind.
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