Chemical Test's

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Created by
Saftar

Cards (8)

  • What is a Biuret test used for?
    Proteins. Colour change if positive Blue -> Purple
  • What is the Benedict test for?
    • Reducing Sugars, which include all monosaccharides and some disaccharides. (Sucrose is a non-producing reducing sugar)
    • They are known as reducing sugars because they can reduce or give electrons to other molecules.
  • What is the procedure for Benedict's test?
    1. Place sample of the food to be tested in a boiling tube
    2. Add excess benedicts solution and then heat in a water bath at 80C for 3 minutes
    3. If a reducing sugar is present an orange-red precipitate will form (when low levels of sugar are present content may appear yellow or green)
  • Whats the Procedure for Benedict's test for non-reducing sugars?
    1. Test a sample for reducing sugars to check that there are none in there in the first place (solution should stay blue)
    2. Take a separate sample and boil it with hydrochloric acid to hydrolyse the sugar into monosaccharides.
    3. Cool the solution and use sodium hydrogen carbonate solution to neutralise it
    4. Test for reducing sugars again A positive result indicates that a non-reducing sugar was present in the original sample.
  • What is the Reagent test strip used for?
    To test for reducing sugars, useful for Urine/blood to test for diabetes.
  • What is the procedure for an Iodine test?
    1. Add a few. drops of iodine solution to a sample
    2. If starch is present the change will be Yellow/Orange/Brown -> Blue-Black
  • What is the procedure for the emulsion test?
    1. Take a sample and mix it thoroughly with ethanol.
    2. Filter
    3. Pour the solution into the water in a clean test tube
    4. A cloudy while emulsion indicates the presence of lipids.
  • 5 Stages of Transcription:
    1. A gene unwinds and unzips by a Helicase enzyme
    2. Hydrogen bonds between complementary nucleotide bases break
    3. The enzyme polymerase catalyzes the formation of temporary hydrogen bonds between nucleotides and their complementary unpaired bases. This strand is a template strand. - mRNA ACGU - DNA ACGT
    4. A length of RNA that is complementary to the template strand of the gene is produced. It is therefore a copy of the other DNA strand - the coding strand
    5. The mRNA now passes out of the nucleic pore, and attached to a ribosome.