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What are the 3 distinguishing features of collagen?
- Right-handed triple helical domain
- Contains hydroxyproline
- Glycine is every 3rd AA in helix
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What are the primary, secondary, and tertiary structures of collagen?
- 1 alpha-chain
- L-handed alpha-helix
- R-handed super triple helix
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What is the AA pattern in the primary structure of collagen?
Gly-X-Y
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What causes coiling in the secondary collagen structures?
- Steric repulsion btwn Pro at X position and Hyp at Y
- Hyp stabilizes helix
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What forms "ghosts" in collagen?
Endomysium
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What type of collagen is in rat tail tendon?
Type 1
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What is the structure of proteoglycans?
- Protein backbone
- Polypeptide branches
- Glycosaminoglycan sub branches (leaves)
- Recurring disaccharide units
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What are the 3 glycosaminoglycans in a collagen proteoglycan?
- Hyaluronic acid
- Dermatan sulfate
- Chrondroitin sulfate
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What do network collagens form and what do they regulate?
- Loose tetrameric structures; skeleton of basement mem collagen
- Cell adhesion and migration
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What type(s) of collagen are in the epimysium?
Type 1
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What type(s) of collagen are in the perimysium?
Type 1, 3, 5
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What type(s) of collagen are in the endomysium?
Type 1, 3, 4, 5
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What types of collagen are in cartilage?
2, 9, 11
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What types of collagen are in skeletal muscle?
1, 3, 4, 5
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What types of collagen are in basement mem?
4, 6, 13, 15, 18, 19
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What types of collagen are in
10
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What types of collagen are in tendon?
1, 3, 5
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What types of collagen are in cornea?
1, 5, 8
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What types of collagen are in skin?
1, 3
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What is the process of cross linking in collagen?
- Allysines bind to hydroxyallysines = aldimines
- Aldimines reconfigure into keto-amines
- Keto-amines re-arrange into cross-links = mature
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What are 2 mature (trivalent) cross-links?
- Pyridinoline
- Ehrlich's chromogen
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What are the 7 muscle shapes?
- Fusiform
- Parallel
- Convergent
- Unipennate
- Bipennate
- Multipennate
- Circular
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Why is red meat red?
- High in myoglobin
- High in hemoglobin
- Dense capillary bed
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Why is white meat white?
Relies on incomplete oxidation of glycogen
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What are 2 factors affecting muscle physiological behaviour?
- Speed - fast/slow
- Fatigue - tonic/phasic
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What determines the speed of muscles?
Myosin isoforms due to light chain differences
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What are the 3 muscle fiber types?
- Type I - slow oxidative (red)
- Type IIA - fast oxidative & glycolytic (intermediate)
- Type IIB - fast glycolytic (white)
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What are the characteristics of slow muscle fibers (Type I)?
- ^[myoglobin]
- dense cap bed
- most mitochondria & lipid
- increased protein turnover
- wide Z-line
- smaller than fast
- most sarcoplasm
- longitudinal striations
- resist fatigue
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What are the characteristics of fast oxidative/glycolytic muscle fibers (Type IIA)?
- ^mitochondria
- fast/repetitive motions
- recruited after slow ox (Type I)
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What are the characteristics of fast glycolytic muscle fibers (Type IIB)?
- large
- well organized SR
- few mitochondria
- ^ATP & creatine phosphate
- most glycogen
- more connective tissue
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What are the different stains for key enzs?
- NADH tetrazolium reductase (red)
- Succinate dehydrogenase (red)
- ATPase (white)
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What determines muscle fibre type?
- Nerves
- Low freq AP - red
- High freq AP - white
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What does grain-feeding increase?
Fat & cholesterol
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What does pasture-feeding increase/decrease?
- Increases linolenic acid
- Decreases linoleic acid
- Increases poly-unsat FAs
- Increases CLA
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How does grain feeding affect carcass quality?
- White fat
- Firmer when cooled
- Increased shelf-stability
- Reduced rate of oxidation/rancidity
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How does pasture feeding affect carcass quality?
- Yellow fat
- Softer when cooled
- Decreased shelf-stability/increased oxidation & rancidity unless Vit E in feed
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What are the 3 flavour/tenderness evaluation techniques?
- Consumer sensory panel
- Trained sensory panel
- Warner-Bratzler Shear force
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How does Vitamin D3 affect toughness?
- Decreases toughness
- Increases muscle Ca so increases calpain activity (proteolytic enz)
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How do implants affect toughness?
- Increase toughness
- Increased FE
- Estrogen leads to cessation of bones
- Leads to mature rather than youthful grade
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What are the affects of beta-adrenergic agonists?
- Increase toughness
- Increase gain
- Increase FE
- Increase carcass protein deposition
- Reduce subcue fat
- Most muscle hypertrophy
- Does not affect marbling
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What is the dressing process for slaughtered cattle and pigs?
- Head removed & inspected
- Esophagus clipped
- Feet or toenails removed
- Tail removed (cattle)
- Bunged
- Carcass to gambrel
- Hide removed (cattle)
- Mamm gland/testes removed
- Eviscerated
- Split
- Hot water washed
- Weighed/refrigerated
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How are animals other than mature cattle, pig, bird, or goat "dressed"?
- Remove head, skin, mamm glands
- Remove feet at carpel/tarsal joints
- Eviscerate
- Split (except sheep, calf, rabbit)
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How are pigs & goats "dressed"?
- Remove hair, toenails, mamm glands
- Eviscerate
- Split (pigs)
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What are the specified risk materials?
- OTM
- - skull
- - trigeminal ganglia
- - eyes
- - tonsils
- - spinal cord
- - dorsal root ganglia
- All ages
- - Distal ileum + 200 cm proximal (Peyer's patches)
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How can UTM cattle be verified using dentition?
- They will not have the 3rd permanent incisor
- 15 month - will have full set of 8 temp teeth
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How is Trichinella spiralis controlled?
- Cook pork at 58.5C for at least 10min
- Freeze at -20C for at least 3d
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What is the life cycle of Trichinella spiralis?
- Larvae encyst in pig muscle (red meat)
- Human eats infected meat
- Digestive juices break down larval capsule
- Mature to adult, lay eggs
- Eggs absorbed
- Travel to muscle/heart/brain
- Encyst in tissue
- Cause issues (muscle-bad flu, heart-arrhythmia, brain-stroke)
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How long must SRM removal records be kept?
- 10 years
- Takes 10 years to get BSE-free status
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What lymph nodes are inspected PM in the skull?
- Retropharyngeal (at back near nasal cavity)
- Parotid (sides of head)
- Submaxillary (under tongue)
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What lymph nodes are inspected PM in the lungs?
- L bronchial
- R bronchial
- Mediastinal (middle of lung)
- Open trachea & look for abnormalities
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Why are the Masseter (cheek) muscles sliced open and inspected?
- Look for Cysticercus bovis (Taenia saginata in humans)
- Forms visible cysts
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