Biochemistry

    Cards (74)

    • Monomer is one of many small molecules that combine together to form a polymer.
    • Monosaccharide is a single sugar e.g. glucose. The monomers of long chain carbohydratepolymers.
    • Alpha glucose is an isomer of glucose that can bond together to form starch or glycogen.
    • Beta glucose is an isomer of glucose that can bind together to form cellulose
    • Disaccharides are made up of two sugar units that are formed by a condensation reaction.
    • Glucose is a single sugar which is used in respiration
    • Monosaccharide is a single sugar e.g. glucose
    • Non reducing sugar is a sugar which can't serve as a reducing agent
    • Reducing sugar is a sugar that serves as a reducing agent
    • FUNCTIONS OF CARBOHYDRATES:
      They provide a chemical store of energy which is released in respiration
      Are involved in storing energy(glycogen in mammals, starch in plants)
      They form part of cellulose in plant cells
    • General formula of Monosaccharides: (CH2O)n
    • Isomers are compounds with the same molecular formula but a different structural formula
    • Test for Reducing sugars
      Benedicts solution+heat --> blue --> red(+result)
    • How can Benedict's test be Semi Quantitative?

      A spectrum of colours can be obtained as a measure of how much reducing sugar is present in a sample
    • Order of colours from non reducing sugars to high reducing sugars

      blue,green,yellow,brown,red
    • Reducing sugar practical to predict mass of glucose
      1. Label six test tubes 0, 0.1, 0.5, 1, 2 and 4 %s
      2. Add 5cm cubed benedicts solution to each
      3. Add 0.5cm cubed of each of the glucose solutions to their test tubes.
      4. Stir each with a glass rod
      5. Place all in hot water bath for 2 mins.
      6. Remove and place in a rack. Stir with rod again
      7. record colour observations in a table
    • How does a colorimeter work when measuring the conc of sugar ?

      The solution is placed in a curvette which goes into a smaller chamber in the colorimeter. It shines a beam of light through the sample. A photoelectric cell picks up the light that is passed through the sample on the other side and provides a reading of amount absorbed. Use a red filter in colorimeter as its complementary to the blue benedicts. The blue benedicts will absord red light. As the conc of sugar increases, absorbency rates will be lower.
    • Alternative way to estimate the concentration of reducing sugar in a sample 

      The more reducing sugar there is present, the more red precipitate will be formed and the more Benedict's solution(copper sulphate) will be used up. The precipitate is filtered so the concentration of the remaining solution can be measured. This will tell you how much Benedict's solution has been used up. The more used up, the more the more reducing sugar is present.
    • Condensation reaction joins two monomers together with the formation of a covalent bond and involves the loss of a water molecule
    • Hydrolysis reaction breaks the covalent bond between two monomers and involves the use of a water molecule
    • 1,4 glycosidic bond means the bond is between the first carbon of one glucose and the 4th carbon of the other.
    • The 3 disaccharides and what monomers they contain

      Maltose- 2 alpha glucose monomers
      Sucrose- one alpha glucose and one beta fructose joined by a 1,4 glycosidic bond
      Lactose- one alpha glucose and one beta galactose joined by a beta 1,4 glycosidic bond
    • Test for non-reducing sugars
      Carry out the test for reducing sugars. If the solution stays blue, take another 2cm3 of the food sample(liquid form) and add to 2cm3 of dilute HCl. Place in hot water bath for 5 mins. The HCl will hydrolyse the disaccharides and polysaccharides into their monosaccharides. Add some sodium hydrogen carbonate to neutralise the test tube as Benedict's wont work under acidic conditions. Use pH paper to check if neutralised. Retest the solution by adding 2cm3 of Benedicts and heating.
    • ATP consists of adenine, ribose and 3 phosphate groups
    • Energy is released when ATP is hydrolysed to form ADP and a phosphate molecule. This reaction is catalysed by ATP hydrolyse. The energy comes from the bonds between the phosphate molecules. These bonds are very stable and have a low activation energy. Breaking of these is quick and releases bursts of energy
    • Properties of ATP
      • Immediate energy. Can be broken down by a single step to release a manageable quantity of energy.
      • Isn't stored in large quantities as it can be easily reformed from ADP in seconds
      • Used in different ways e.g. metabolic processes, movement, active transport, secretion and activation of molecules.
    • What is the reason for water being polar?
      Due to the uneven distribution of charge within it
    • How does the oxygen atom in water affect its charge distribution?
      The oxygen atom attracts electrons more strongly than hydrogen atoms
    • What type of charge does the oxygen atom in water have?
      A slight negative charge
    • What type of charge do the hydrogen atoms in water have?
      A slight positive charge
    • What role does water play in metabolic reactions?
      • Acts as a metabolite
      • Involved in condensation reactions
      • Involved in hydrolysis reactions
    • Why is water considered a good solvent?
      It allows gases, enzymes, and waste products to readily diffuse
    • What is the significance of water's high specific heat capacity?
      It minimizes temperature fluctuations and acts as a buffer
    • Why do water molecules require a lot of energy to break their bonds?
      Because they stick together with hydrogen bonds
    • What helps water to minimize temperature fluctuations?
      Its high specific heat capacity
    • Properties of water
      • Large latent heat of vaporisation because the hydrogen bonds require a lot of energy to evaporate one gram of water. Evaporation of water provides a cooling effect with little water loss e.g. sweating.
      • Strong cohesion between molecules supports columns of water and enables transport of water through tubes e.g. xylem.
    • Test for Starch
      Add iodine. If starch is present iodine yellow/brown to blue/black
    • Starch is a mixture two polysaccharides: amylose which is a long unbranched forms coiled shape and amylopectin which is a long branched chain
    • Features of Starch
      • Compact due to the amylose coiling so it can be stored in smaller places.
      • Easily hydrolysed due to the amylopectin being branched so enzymes have more ends to act upon so glucose monomers can be released quickly
      • Insoluble so water is not drawn in by osmosis and lyse the cell
      • Large and insoluble so it doesn't diffuse out of the cell
    • Features of Gylcogen
      • Insoluble so water isn't drawn in by osmosis and so it doesn't diffuse out of the cell
      • Compact so a lot of it can be stored in a small space
      • More highly branched than starch so has more ends, meaning enzymes can act on these and break them down into glucose faster. This high respiration rate supports the high BMR in animals.
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