AN SC 260 - 4

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AN SC 260 - 4
2012-10-15 14:50:10
AN SC 260

Chapter 4 - Carbohydrates in Animal Nutrition
Show Answers:

  1. What are the functions of carbs?
    • Major components of plant tissue
    • Main energy source for most livestock
    • Free CHO central to metabolism
  2. What are some examples of monosaccarides?
    • Glucose - hexose/dextrose
    • Fructose
  3. What is important about glucose?
    • Ultimate source of E for most animal cells
    • Central to metabolism
    • No degradation needed for absorption
  4. What are some examples of disaccharides?
    • Sucrose
    • Lactose
    • Maltose
  5. What does sucrase do and what is released?
    Hydrolyzes sucrose

    Glucose and fructose released
  6. What is maltose a product of and where is it present?
    Starch Digestion

    Germinating Grain (beer production)
  7. What are the bonds found in polysaccharides?
    Alpha and Beta
  8. What significance do alpha and beta bonds have?
    Animals can break down alpha bonds but not beta bonds

    Microbes in ruminants can break down beta bonds
  9. What bonds are found in starch?
    Amylose - alpha-1,4 linked glucoses

    Amylopectin - alpha 1,4 linked glucoses with alpha-1,6 branches
  10. Why is starch more soluble in hot water than in cold water?
    Insoluble in cold water

    When heated, water in starch will gelatinize which increases accessibility by enzymes
  11. What happens amylose and amylopectin upon cooling after gelatinization?
    • Amylose - re-crystalizes
    • Amylopectin - gels
  12. What are some properties of Cellulose?
    • Unbranched chain of beta-1,4 linked glucoses
    • Most abundant plant constiuent
  13. What are some properties of hemicellulose?
    • Branched
    • More digestible than cellulose
    • Acid releases arabinose side chains
  14. What is lignin?
    • Derived from wood
    • Not a carb
    • Repeating phenylpropane units
  15. What are soluble fibres?
    • Soluble non-starch polysaccharides
    • beta-linked sugar molecules (indigestible by animals)
    • beta-glucans
  16. What is an example of a soluble fibre?
  17. What is starch broken down by and where?
    • Amylase
    • Mouth(saliva), Pancreas
  18. What are the steps of starch breakdown?
    Starch => dextrins => maltose => glucose
  19. Where does most of absorption occur?
    Small intestine - duodenum & jejunum (mostly beginning of jejunum)
  20. How glucose transported across the membrane?
    • Facilitated
    • Sodium symport - 2 Na+ per 1 glucose
    • Down [] gradient
  21. What are the precursors for gluconeogenesis?
    • AAs
    • Lactic Acid
    • Fat (glycerol, no net synth of glucose)
  22. Why is it important to replenish glycogen stores?
    • Reserves only stored in liver for 1/2 day
    • Brain & red blood cells completely dependent on glucose for E
  23. What are the steps of glycolysis and how many ATP are produced?
    • Glucose => fructose 1,6 bisphosphate => pyruvate
    • Net 8 ATP generated

    • Pyruvate => 2 Acetyl CoA
    • 6 ATP

    • 2 Acetate => 2 CO2 + 2 H2O
    • Net 24 ATP generated

    TOTAL 38 ATP
  24. What is the precursor for fat synth?
    Acetyl CoA
  25. What is ketosis?
    • Not enough glucose in blood
    • Fat metabolized for energy
    • Ketones produced faster than can be metabolized
  26. What is insulin-dependent diabetes mellitus (Type I) caused by?
    Destruction of Islets of Langerhans in pancreas
  27. What is non-insulin-dependent diabetes mellitus (Type II) caused by?
    • Deficiency of cell-surface binding sites for normal glucose uptake
    • Aggravated by obesity
  28. What is the most important form of diabetes in domestic animals?
    Gestational diabetes mellitus