Biological Molecules

HideShow resource information
  • Created by: mrahman
  • Created on: 26-10-15 19:12
View mindmap
  • Biological Molecules
    • Carbohydrates
      • made from carbon, oxygen and hydrogen
      • Monosaccharide- simple sugars that dissolve in water and taste sweet
        • Glucose a monosccharide can exist in 2 forms
          • Alpha Glucose
          • Beta Glucose
      • Disaccharide formed when two monosaccharide join together by a glycosidic bond in a condensation reaction
        • Maltose formed by 2 alpha glucose in 1,4 glycosidic bond
        • Lactose formed by galactose and glucose
        • Sucrose formed by fructose and glucose
        • Disaccharides can be broken down to monosaccharide by hydrolysis
      • Polysaccharides- formed when lots of monosaccharide join together by condensation reaction. Insoluble because of large size
        • Starch
          • Two constituent part: Amylose and Amylopectin
            • Amylose formed by alpha 1,4 glycosidic bonds of glucose. Held together by hydrogen bonds so has a coiled structure
            • Amylopectin has many branches because the monosaccharide is joined together by alpha 1,4 and alpha 1,6 glycosidic bond.
          • the coiled structure and branches provides starch with compactness.combined with its insolubility makes starch an ideal energy storage.
            • Insolubility also means that it doesn't effect the movement of water.
        • Glycogen
          • formed by alpha 1,4 and alpha 1,6 glycosidic bond between glucose. 1,6 bond occurs more frequently it has more branches
          • More branches means its more compact so it serves as energy storage in animals.
        • Cellulose
          • Formed by Beta Glucose joined together in 1,4 glycosidic bonds. Has no branches so the chain is long and straight. The chains are able form large numbers of hydrogen bonds between them which forms a group of molecule called microfibrils.
          • The huge number of hydrogen bond provides it great strength and stability making cellulose ideal for structural substances.
    • Lipids
      • also made from hydrogen carbon and oxygen. but the ratio and arrangement is different
      • Two types: Phospholipids and Triglycerides (fats and oils)
        • Triglycerides
          • Made from 1 glycerol molecule and 3 fatty acids. These are joined together by an ester bond in condensation reactions.
          • The fatty acids can be saturated and unsaturated. Triglycerides with one unsaturated fatty acid is called unsaturated triglyceride, two or three fatty acids it's called polyunsaturated triglyceride
          • Animal triglycerides are usually saturated and plant triglycerides are usually unsaturated
            • Triglycerides act as energy storage in both animals and plants. They have more energy per gram compared to carbohydrates. In plants they are found in seeds where they serve as lightweight energy storage when they germinate.
        • Phospholipids
          • Made from 1 glycerol, 2 fatty acids and a phosphate group
            • Phosphate group is hydrophillic and fatty acids are hydrophobic. So in water the head is faced down and the tail is up.
            • Untitled
    • Monomers- small molecules joined together to make larger molecules
    • Polymers- long chains of monomers joined together
    • Condensation Reaction- process by which monomers are joined together and water is removed
    • Hydrolysis reaction- the process by which larger molecules are broken down by the addition of water
    • Tests
      • Reducing sugar: heat with Benedict's Reagent and a precipitate of brick red should form
        • Non reducing sugar: boil it with dilute acid and neutralise the acid with hydrogen carbonate. Then perform the Benedict's test.
          • Starch: add iodine in potassium iodide to the substance, it should turn blue black in presence of starch.
      • Protein: Gently mix the substance with the biuret reagent. it should turn lilac or purple in the presence of protein
      • Lipids: Add the substance to ethanol in a clear test tube. Any lipid present will dissolve. Then transfer the mixture to another tube containing water, the dissolved lipids should form droplets called emulsion of milky white colour.
    • Proteins
      • Polymers made from 20 different types of naturally occurring amino acids.
        • Amino acids have a an amine group a carboxyl group and a R group that varies attached to the central carbon atom.
      • When amino acids join together they form peptide bonds. A long chain of these amino acids joined together are called a polypeptide chain. This chain is know as the primary structure.
        • The  polypeptide chain can coil or pleat. This coiling or pleating occurs because hydrogen bond that forms between oxygen in one amino acid and hydrogen in another. This is known as the secondary structure.
          • The secondary structure folds again forming complex 3d shapes. These shapes are held together by a combination of van der waals, hydrogen bonds, ionic bonds and disulfide bridges. This is the tertiary structure which is unique to every protein.
            • Some proteins are formed from multiple polypeptide chains. These are called the quaternary structure.
              • Haemoglobin contains four four polypeptide chains 2 alpha and 2 beta. Also has an extra group which helps with the transport of oxygen in blood.
  • Carbohydrates


No comments have yet been made

Similar Biology resources:

See all Biology resources »See all Biological molecules resources »