Chemical Aspects of Life Lab 4

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Chemical Aspects of LifeLab 4

• Pre-lab Discussion

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Background

• In this lab you will be testing for the presence
  of the following substances
• Carbohydrates
• Proteins
• Lipids
• You will use various chemical indicators to test
  for the presence of these substances.
• Carbohydrates will be tested with Benedicts
  solution and Iodine solution
• Proteins will be tested with Biurets solution
• Lipids will be tested with Sudan IV
• Use the following chart as a reference

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The Carb Test with Benedicts

• The carbohydrate test is the most confusing. You
  really need to understand the difference between
  monosaccharides and disaccharides
• Monosaccharides include
• Glucose
• Fructose
• Galactose
• Disaccharides include
• Maltose glucose glucose
• Lactose glucose galactose
• Sucrose glucose fructose
• Remember Disaccharides are formed by a
  condensation reaction. Once a chemical reaction
  has occurred you have an entirely new product.
  The reactants are gone.

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The Benedicts Test

• Benedicts Solution is a blue indicator solution
  that reacts with monosaccharides. It will turn
  one of three colors depending on the
  concentration of monosaccharides in solution.
• Red-brownhigh concentration of monosaccharides
• Orangemoderate concentration of monosaccharides
• Greenlow concentration of monosaccharides.
• Blueno monosaccharides

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Carbohydrate Hypotheses

• You will be testing 5 Glucose solution and 5
  Sucrose solution with Benedicts Solution. Write
  a hypothesis for each of these tests.
• If Benedicts is added to 5 Glucose solution
  then.
• If Benedicts is added to 5 Sucrose solution
  then
• Hydrochloric acid can be added in place of water
  to produce a hydrolysis reaction. During this
  reaction, a disaccharide can be broken down into
  two monosaccharides. You will be testing 5
  Sucrose HCl with Benedicts Solution. Write a
  hypothesis for this test.
• If Benedicts is added to Sucrose HCl then

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• Starch is a very large polysaccharide made when
  hundreds of glucose molecules join together
  through numerous condensation reactions.
• You will be testing Starch and Benedicts
  solution. You will also be testing Starch HCl
  and Benedicts solution.
• Write a hypothesis for each of these tests.
• If Benedicts is added to a Starch solution then
• If Benedicts is added to a Starch HCl solution
  then

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The Carb test with Iodine

• Iodine can be used to test for polysaccharidespar
  ticularly Starch
• Iodine turns blue black in the presence of
  starch.
• You will test starch and water with iodine.
• Important test will be used many times this
  year. Write Hypotheses statements for each of
  these tests.
• If iodine is added to a starch solution, then
• If iodine is added to water, then.

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Protein Tests

• Biuret solution is a blue solution that turns a
  violet color in the presence of proteins
• You will be testing egg albumin and gelatin with
  Biurets solution. Write hypotheses statements
  for each of these tests.
• If Biuret solution is added to egg albumin, then
  
• If Biuret solution is added to gelatin, then.

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Lipid Test Grease Spot

• Lipids in solution will leave a transparent spot
  on a brown paper bag.
• You will test oil, water and milk by placing
  drops of each on a brown paper bag. Write
  hypotheses statements for each test.
• If a drop of oil is placed on a piece of brown
  paper bag, then
• If a drop of water is placed on a piece of brown
  paper bag, then
• If a drop of milk is placed on a piece of brown
  paper bag, then

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Lipid Test Sudan IV

• Sudan IV is a red dye that is soluble in lipids,
  but not soluble in water. (Soluble means that it
  will dissolve in solution. Insoluble will float
  or sink).
• You will be adding Sudan IV to a mixture of water
  and oil and then to a mixture of water and milk.
  Write hypotheses statements to predict where you
  will see the red color in the test tubes.
• If Sudan IV is dropped into a water and oil
  mixture, then the dye will
• If Sudan IV is dropped into a water and milk
  mixture, then the dye will