Ex. 38 - The isolation and identification of a protein

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Ex. 38 - The isolation and identification of a protein
2010-04-05 19:43:55

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  1. Why should you were eye protection for this lab?
    To protect against possible shattering of dropped glassware and spilage of corrosive nitric acid and sodium hydroxide
  2. Nitric acid, HNO3, and sodium hydroxide, NaOH, are ______. Mercuric nitrate and lead nitrate, are ______.
    corrosive; toxic metabolically
  3. What are large molecules found in the cells of living organisms and in biological fluids such as blood plasam.
  4. What are the 5 elements found in proteins?
    Carbon, hydrogen, oxygen, nitrogen, and sulfur
  5. What is the range for the molecular weight of a protein?
    5000 to several million
  6. How many different types of amino acids can function as subunites of a protein?
  7. Some proteins are relatively inert fibers, such as the _____ of wool and hair; some are like the _____ of tendons and connective tissue, which play an important structural role in animals; others are found in egg white and blood plasma and are ______ and water soluble.
    keratins; collagens; globular
  8. One group of proteins called the ______ are the essential catalysts of biological systems.
  9. Enzymes enable reactions to proceed at a very ____ rate under very moderate conditions.
  10. How are peptide bonds formed?
    when an acid group undergoes a reaction with an amino group
  11. What gives a protein its ablility to become very long and causes the molecular weight to rise and become very high?
    amino acids contain at least one acidic group that can link to one amine or basic group
  12. Can an amino acid contain more than one amine group or acidic group?
  13. Since they're are both acidic and basic groups in amino acids, what dectates the specific funtion of the moleculer structure?
    the basicity or acidity or the solution
  14. When a large molecule has a net positive or negative charge, how does this effect its solubility in water?
    it enhances its solubility
  15. When there is no charge or when the postive and negative charge is equal (isoelectric point), how does this effect its solubility in water?
    it becomes less soluble
  16. What is the principal protein in milk?
  17. How is casein separated from milk?
    by acidification
  18. Acidfication of milk causes what to form?
    a precipitation of casein and some fat
  19. One of the by-products in the acidification of milk is fat, how is it removed from the solution? Why does this work?
    by washing the precipitation with alcohol, because the fat is soluble in alcohol while the protein is not.
  20. What represents a postive test for protein?
    the presense of casein
  21. What is the formula to find the percentage of casein in milk?
    % casein = weight casein/ 100g milk x 100%
  22. What characteristic does ether have that makes it dangerous in lab? What precaution should be taken in using ether?
    Ethers are flammable. Use under a hood.
  23. What is the obvious difference between protein molecules and the common molecules encountered in other labs, such as water, ammonia, sugar, and alcohol?
    proteins are large molecules
  24. What is the action of heavy metal ions on proteins?
    they can cause serious damage to proteins
  25. Name two types of functions carried out by proteins in the human body.
    structural roles and catalyst
  26. What is the reason for adding ethanol and ethanol-ether solutions to the precipitate?
    to remove the fat by-product