AN SC 420 Quiz 1

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ebacker
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257996
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AN SC 420 Quiz 1
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2014-01-23 02:20:34
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AN SC 420 University Alberta Carcass Meat Quality
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Carcass and Meat Quality
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  1. What are the 3 main proteins in meat?
    • Myofibrillar (myosin, actin)
    • Sarcoplasmic (enzs, myoglobin, forms gel around cooked meat)
    • Connective (collagen, elastin)
  2. What provides glysine to meat?
    • Collagen
    • Every 3rd AA is gly in collagen
  3. What are the 4 lipids in meat?
    • Triglycerides (marbling)
    • Phospholipids (mems)
    • Glycolipids (nerves)
    • Cholesterol (mems, fluidity, sex hormones)
  4. What are the 5 principal phospholipids?
    • Phosphatidyl choline
    • Phosphatidyl ethanolamine
    • Phosphatidyl inositol
    • Diphosphotidyl glycerol
    • Phosphatidyl serine
  5. What are the 2 essential FAs?
    • Linoleic
    • Alpha-linoleic
  6. What is the limited FA?
    Arachidonic
  7. What FAs are present in grain-fed animals?
    • Oleic acid (C18:1 c-9)
    • Linoleic acid (C18:2)
    • Linoleic acid (C18:3)
  8. What FAs are present in grass-fed animals?
    Long-chain n-3 polyunsaturated FAs
  9. What are the 5 fat depots in an animal?
    • Subcutaneous
    • Intermuscular (seam fat)
    • Intramuscular (marbling)
    • Cell mems
    • Body cavity (perirenal, vascular, carcass)
  10. What are the 2 form of carbs?
    • Monosaccharides
    • Glycogen/Lactic acid
  11. What are the 2 main minerals?
    • Heme iron
    • Zinc - wound healing, immunity, DNA synth
  12. Importan points about Conjugated Linoleic Acid
    • Mix of linoleic acid positional & geometric isomers
    • Anti-cancer properties
    • C9, t11 most common
    • Precursor to stearic acid
    • ^ linoleic acid in diet = ^ CLA in meat
    • 1. Myofilament - thick & thin filaments
    • 2. Myofibril - sarcoplasmic reticulum
    • 3. Muscle fibre - endomysium
    • 4. Muscle fibre bundle / Fascicles - perimysium
    • 5. Muscle - epimysium
    • 1. Thick filament
    • 2. Thin filament
    • 3. Z disc
    • 4. I band
    • 5. A band
    • 6. H zone
    • 7. M line
  13. What is the basic structure of myosin?
    • 6 subunits
    • 2 globular heads
    • 1 alpha-helical tail
  14. When does myosin hydrolyze ATP to ADP?
    In the presence of Mg2+
  15. What does myosin bind to?
    Filamentous actin
  16. What are the 2 light chain types of myosin?
    • ELC - essential light chain, essential for binding to actin
    • RLC - regulatory light chain, non-essential, phosphorylated
  17. What drives the formation of thick filament?
    Tail region of myosin
  18. What are the 2 most abundant myofibrillar proteins?
    • 1. Myosin
    • 2. Actin
  19. What are the 2 forms of actin?
    • Globular (G) - in low salt more attracted to water than self so forms individual units
    • Filamentous (F) - in physiological salt, in muscle
  20. What is the structure of F actin?
    Helix of actin molecules, looks like string of pearls twisted on itself
    • 1. Myosin binds to actin 
    • 1a. Inorganic phosphate released
    • 2. Ca from nerve impulse, myosin swivels on actin, pulls thin/thick fils past e/o, POWER STROKE
    • 2a. ADP released
    • 3. No ATP, myosin & actin bound, RIGOR
    • 3a. ATP added
    • 4. Actin detaches
    • 4a. ATP hydrolyzed
    • 5. Close to e/o, myosin head cocked, REST
    • 1. Actin
    • 2. Tropomyosin
    • 3. Troponin complex
  21. What are the 3 troponin complexes?
    • TnI - binds to actin
    • TnC - binds to Ca ions
    • TnT - binds to tropomyosin
  22. What is the relationship between Ca, TnC, tropomyosin, and a power stroke?
    • Ca binds to TnC
    • Tropomyosin has less affinity for actin, moves out of the way
    • Myosin binds to actin
    • Power stroke
  23. What are the 2 types of Ca binding sites on TnC and which is responsible for a power stroke?
    • High affinity
    • Low affinity - power stroke, allows easy release
  24. What is like a line-dance at a wedding? Why?
    • Myofibrillar structure
    • Mitochondria/nuclei = feed protein synthesis, tables along outer wall of dance floor, move out of the way for the line-dance
    • Filament movement = line-dance
  25. Na-K pump ratio
    • 3 Na out : 2 K in
    • Returns to original location via diffusion
  26. Resting mem potential
    -85 to -90 mV
  27. What happens to mem potential as nerve impulse travels down axon?
    • Depolarization - Na flow in
    • Repolarization - K flow out
    • Impulse reaches voltage gated channels
    • Returns to Na/K pump
  28. How many neuromuscular junctions are there per muscle fiber and where are they located?
    • 1
    • Mid-secion of each muscle fiber, outside plasma mem
  29. What are DHPRs and where are they located?
    • Dihydropyridine receptors
    • Transverse tubule mem
  30. What effect does an action potential have on DHPR?
    • Changes conformation
    • Triggers release of Ca from Ryr1 in SR
  31. Where is Ryr1 located?
    Junctional region of SR mem
  32. What is Ryr1 and what role does it play?
    • Ryanodine receptor
    • Controls release of Ca that causes muscle contraction
  33. How does transverse tubule depolarization effect Ca release?
    • Triggers DHPR to change conformation
    • This triggers Ryr1 linked to DHPR to release Ca
    • Ca triggers release of Ca from Ryr1 not linked to DHPR
  34. What are the main properties of Calsequestrin?
    • Glycoprotein
    • In SR
    • Binds releasable Ca, high capacity
    • Random conformation, becomes helical as Ca binds
    • Low ionic strength - inhibits Ryr1
    • High ionic strength - increased Ryr1 activity
  35. How is Ca retrieved from the sarcoplasm?
    • Mg2+, Ca2+-ATPase
    • Facilitated by dense coverage of SR by ATPase
  36. Define isometric
    Muscle contracts but does not shorten
  37. Define isotonic
    Muscle contracts and shortens, tension remains constant
  38. How does the Ca2+-ATPase pump work?
    • Mg-ATP binds to ATPase
    • ATPase changes conformation
    • 2 Ca2+ bind to ATPase
    • ATP hydrolyzed
    • ATPase changes conformation
    • Ca released to SR lumen

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