Protein Metabolism Flashcards

1
Q

What is a peptide?

A

short chain of AA (less than 50)

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2
Q

What is a protein?

A

a long chain of AA
-sequence will determine shape and function

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3
Q

What is an essential AA?

A

-cant be synthesize by the body of cant be synthesized at a high enough rate to support the need
-required in diet

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4
Q

What is a nonessential AA?

A

cant be synthesized at a high enough rate to support the body’s needs
-does not need to be included in diet

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5
Q

What are conditionally essential AA?

A

non essential AA may become essential if the rate of synthesis is not high enough to meet the demand

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6
Q

What is a semi essential AA?

A

synthesized from essential AA
-if there is not enough of the essential AA precursor in the diet, these AA become essential

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7
Q

What are the essential AA?

A
  1. Phenylalanine
  2. Valine
  3. Threonine
  4. Tryptophan
  5. Isoleucine
  6. Methionine
  7. Histidine
  8. Arginine
  9. Lysine
  10. Leucine
    (PVT TIM HALL)
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8
Q

What are the non essential AAs?

A
  1. Cysteine
  2. Alanine
  3. Asparagine
  4. Aspartate
  5. Tyrosine
  6. Serine
  7. Glycine
  8. Glutamine
  9. Glutamate
  10. Proline
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9
Q

What are the semi essential AAs?

A

Cysteine and Tyrosine

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10
Q

What is cysteine synthesized from?

A

methionine
-need to include enough methionine in diet to meet the requirement for methionine needs + the synthesis of cysteine
-if include cysteine in the diet, this will have a sparing effect on methionine and decrease methionine requirement

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11
Q

What is tyrosine synthesized from?

A

phenylalanine
-need enough in diet to meet needs + synthesis
-sparing effect

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12
Q

Protein digestion in the stomach deals with?

A

-HCl
-Pepsin

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13
Q

What does the HCL do?

A

denatures protein

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14
Q

What does the pepsin do?

A

pepsinogen is activated by HCL to be pepsin
then pepsin breaks down protein into long peptide chains

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15
Q

How does protein digestion work in the small intestine?

A

-cholecystokinin is secreted when chyme enters the duodenum
-CCK acts on pancreas to secrete digestive enzymes
etc

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16
Q

What digestive enzymes does the pancreas secrete after CCK acts on it?

A

-trypsinogen
-chymotrypsin
-procarboxypeptidase

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17
Q

What is secreted by the brush border?

A

enterokinase
-activates trypsinogen to trypsin

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18
Q

What does trypsin activate?

A

chymotrypsinogen to chymotrypsin & procarboxypeptide to carboxypeptide

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19
Q

What breaks down large peptides into oligopeptides? (<10AA)

A

trypsin, chymotrypsin, & carboxypeptidase

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20
Q

What does aminopeptidase (secreted by brush border) do?

A

breaks down oligopeptides into tripeptides, dipeptides, and free AAs

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21
Q

What do microbes synthesize?

A

microbial protein from dietary protein and AA

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22
Q

Microbial protein leaves rumen for

A

digestion in abomasum and s.i.

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23
Q

Na+ dependent AA transport system

A

transports Na+ into cell w/ the amino acid

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24
Q

Na+ independent AA transport system

A

transports AA into the cell

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25
Q

Peptide transport (Tri and Di-peptide)

A

-transport di- or tri- peptide w/ a H+ into the cell
-cellular aminopeptidases breakdown di- and tri- peptides into free AA
-free AA leave the cell via AA transporters and enter the hepatic portal system

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26
Q

Functions?

A

-maintain body structure
-facilitate mobility
-transport
-metabolism
-regulation
-immune regulation

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27
Q

What is nitrogen balance?

A

measure N intake & excretion

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28
Q

What is positive nitrogen balance?

A

N intake exceeds N excretion

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29
Q

What is nitrogen equilibrium?

A

N intake = N excretion
-indicates maintenance

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30
Q

What is negative nitrogen balance?

A

N intake less than N excretion
-geriatric animals/ disease states

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31
Q

What is dynamic protein turnover?

A

continual degradation and resynthesis of body protein

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32
Q

What is involved in protein synthesis?

A

transcription/ translation

33
Q

Amino acids can be used for

A

protein synthesis, oxidized, or used for the synthesis of non protein metabolites

34
Q

Transcription

A

DNA to RNA

35
Q

Translation

A

RNA to protein

36
Q

What is transcription/translation activated by?

A

insulin

37
Q

What is involved in protein degradation?

A

intracellular proteases

38
Q

What is intracellular proteases?

A

-lysosomal
-ubiquitin

39
Q

What activates intracellular proteases?

A

high concentrations of glucagon (severe starvation)

40
Q

What does amino acid oxidation take place?

A

liver

41
Q

What are AA considered?

A

either glucogenic or ketogenic

42
Q

Glucogenic AA

A

oxidized to glycolytic or citric acid cycle intermediates
-can be used for gluconeogenesis

43
Q

Ketogenic AA

A

oxidized to acetyl CoA
-can be used for ketone body synthesis, FA synthesis

44
Q

Which AA are ketogenic?

A

-lysine
-leucine

45
Q

Which AA are glucogenic?

A

-valine
-threonine
-histidine
-arginine
-methionine
-cysteine
-alanine
-aspartate
-asparagine
-serine
-glycine
-glutamine
-glutamate
-proline

46
Q

Which AA are both?

A

-phenylalanine
-tyrosine
-isoleucine
-tryptophan

47
Q

Various forms of nitrogen excretion?

A

-ammonia (aquatic invertebrates)
-uric acid (birds, insects)
-urea (mammals)

48
Q

What is nitric oxide synthesized from?

A

arginine

49
Q

What is creatine synthesized from?

A

arginine

50
Q

What is choline synthesized from?

A

serine

51
Q

What is histamine synthesized from?

A

histidine

52
Q

What is taurine synthesized from?

A

cysteine
-cant be synthesized by cats

53
Q

What is glutathione synthesized from?

A

cysteine

54
Q

What is Coenzyme A synthesized from?

A

cysteine

55
Q

What is the thyroid hormone synthesized from?

A

tyrosine

56
Q

What is NAD synthesized from?

A

tryptophan

57
Q

What is Melatonin synthesized from?

A

tryptophan

58
Q

What is Carnitine synthesized from?

A

lysine

59
Q

What does a protein concentrate have to have?

A

at least 20% CP

60
Q

What are oilseed meals?

A

-by products of vegetable oil production
-meal remains after oil extraction

61
Q

What is the most important protein supplement for livestock feeding?

A

soybean meal

62
Q

What is the downside with soybean meal?

A

deleterious factors
(protease inhibitors, lectins, goitrogens)

63
Q

Protease inhibitors

A

-inhibit protein digestion
-decrease growth

64
Q

Lectins

A

bind carbohydrates & cause digestive disturbances (diarrhea)

65
Q

Goitrogens

A

inhibit production of thyroid hormone
-causes goiter

66
Q

What is the nutritional content of soybean meal?

A

CP = 44-50%
-low fiber, high quality protein
-high phytate

67
Q

What is the second most important plant protein supplement?

A

cottonseed meal

68
Q

What deleterious factors does cottonseed meal have?

A

Gossypol

69
Q

Gossypol

A

-reduced feed intake & growth
-damage to lungs, liver, heart, anemia
-green yolks in birds

70
Q

What is the nutritional content of cottonseed?

A

whole cottonseed
-23% CP, 23% fat, 17% fiber
cottonseed meal
-41% CP, 12% fiber
cottonseed oil
-contains cyclopropene fatty acids

71
Q

Cyclopropene fatty acids

A

-inhibits desaturases
-hard fat in the meat due to saturated FAs
-pink egg albumin

72
Q

Animal protein sources examples

A

-meat meal
-meat + bone meal
-blood meal

73
Q

Content of animal protein sources

A

-contains vitamin B12
-high quality protein
-concerns with safety (e coli, mad cow disease)

74
Q

What happens to Nonprotein Nitrogen in the rumen?

A

NPN sources are converted to ammonia in rumen
-used by microbes for amino acid synthesis

75
Q

What is the most common NPN source?

A

Urea
-must be careful of urea toxicity
-use at less than 2% of diet

76
Q

Urea toxicity

A

labored breathing, slobbering, bloating, incoordination

77
Q

Other NPN sources

A

-biuret
-dried poultry waste

78
Q

Biuret

A

2 ureas
-brokendown to ammonia more slowly then urea
-takes up to 6 weeks for the microbes to produce enzyme to breakdown