AN SC 260 - 3.1

  1. How many naturally occuring AAs are there?
    How many are found in proteins?
    How many are essential?
    • 300
    • 20
    • 10
  2. What is the common structure of an AA (except proline)?
    Image Upload 1
  3. How are AAs chemically classified?
    • Based on R group
    • Polarity
    • Charge
    • Hydro -phobic vs -philic
    • Branched vs straight
  4. How are AAs nutritionally classified?
    • Based on dietary requirement
    • Indispensible vs dispensible
    • Conditionally indispensible
    • Semi-indispensible
  5. What does semi-indispensible mean?
    Can be sythesized from indispensible precursors

    • Methionine => Cysteine
    • Phenylalanine => Tyrosine
  6. What are 3 examples of indispensible AAs?
    • Arginine
    • Methionine
    • Phenylalanine
  7. What are 3 examples of dispensible AAs?
    • Cysteine
    • Glycine
    • Proline
  8. What are some examples of conditionally essential AAs?
    Arginine - poultry, max growth for some species (dogs, cats, pigs)

    Proline - hens

    Glycine - chicks

    Glutamine - intestinal mucosa during illness
  9. What is Taurine derived from?

    Except in cats, they cannot derive Taruine due to shorter digestive tract
  10. What is special about Taurine?
    • Not in protein
    • Occurs as free AA in cats
  11. What configuration do AAs naturally occur in?
    L configuration
  12. Only L enantiomer absorbed for most AAs except...
    D methianine - the body can absorb and convert to L methianine
  13. What are the levels of organization in proteins?
    Primary structure - AA chain order

    Secondary structure - alpha helix or beta sheet domains

    Tertiary structure - relationships of domains within a chain, protein folding

    Quaternary structure - 2+ polypeptide chains, oligomeric proteins
  14. Proteins are classified on the basis of...
    • Shape
    • Solubilities
    • Other
  15. What are the properties of globular proteins?
    • Soluble in water
    • Dilute acids and bases
    • Alcohols
    • Hydrophobic core
    • Hyphilic surface
  16. What are the functions of globular proteins?
    • Enzymes
    • Messengers
    • Transporters
  17. What are the properties of fibrous proteins?
    • Insoluble in water
    • Resistant to digestive enzymes
  18. What are the functions of fibrous proteins?
    Structural - collagen, elastin, keratins
  19. What are conjugated proteins?
    Contain non-protein compounds

    • Lipoproteins
    • Glycoproteins
    • Mucus
  20. The body cannot absorb intact proteins. What is the one exception to this?
    Collostrum from breast milk for a short period after birth 
  21. What are the different forms of protein digestion and absorption?
    • Cooking
    • Stomach acid
    • Small intestine pH, pancreatic proteases, zymogens, cleaving enzymes, active enzymes
    • Proteases
  22. What are zymogens?
    Inactive precursors of active enzymes so that intestinal wall is not digested.
  23. What are the different cleaving enzyme classifications?
    • Enterokinase
    • Endopeptidases
    • Exopeptidase
    • Active Enzymes
  24. What does enterokinase do?
    Cleaves trypsinogen to trypsin
  25. What are some examples of endopeptidases?
    • Pepsin
    • Trypsin
    • Chymotrypsin
    • Elastase
  26. What is an example of an exopeptidase?
  27. What are some examples of active enzymes that cleave specific peptide bonds?
    • Chymotrypsin
    • Elastase
    • Carboxypeptidase
  29. What are some signs of protein deficiency?
    • Reduced growth
    • Decreased feed efficiency
    • Kwashiorkor - Edema

    Pregnant - Reduced birth weight, milk production
  30. How do AAs regulate protein synthesis?
    Protein synthesis can only occur until the first "limiting" AA is used up, the other AAs are broken down (oxidized)
  31. What are 3 AA interactions?
    Antagonism - reduction in performance that can be overcome by supplementation of a structurally similar AA, ex. lysine and arginine

    Toxicity - adverse reactions of an AA can not be overcome by suplementation of other AA

    Imbalance - dietary proportions of indispensible AA do not meet needs of animal, can be overcome by supplementation
Card Set
AN SC 260 - 3.1
Chapter 3.1 - Amino Acids and Protein in Animal Nutrition