Protein Metabolism Flashcards
1
Q
Why is protein metabolism unique as compared to lipid and carbohydrate metabolism?
A
Protein has many functional purposes in the body and is only used for energy in a starvation state.
2
Q
How many amino acids are there?
A
20.
3
Q
What makes every protein different?
A
The order of the amino acids that make it up.
4
Q
What is a peptide?
A
A short chain of amino acids (max. 50).
5
Q
Where do peptides come from?
A
Protein digestion.
6
Q
What is a protein?
A
Long chain of amino acids that is folded and serves a function in the body.
7
Q
What are the 4 ways amino acids are classified?
A
- Essential.
- Non-essential.
- Semi-essential.
- Conditionally essential.
8
Q
What is an essential amino acid?
A
An amino acid that the body is unable to synthesize or cannot be synthesized at a rate that can meet the body’s demand.
9
Q
What animals are essential amino acids not a concern in?
A
Ruminants.
10
Q
What are the essential amino acids?
A
- Phenylalanine.
- Valine.
- Threonine
- Tryptophan.
- Isoleucine.
- Methionine.
- Histidine.
- Arginine.
- Leucine.
- Lysine.
*PVT TIM HALL.
11
Q
What is a non-essential amino acid?
A
Amino acids that are not required in certain amounts in the diet due to being synthesized by the body at a rate that meets the body’s demand.
12
Q
What are the non-essential amino acids?
A
- Cysteine.
- Alanine.
- Asparagine.
- Aspartate.
- Tyrosine.
- Serine.
- Glycine.
- Glutamate.
- Glutamine.
- Proline.
13
Q
What are semi-essential amino acids?
A
Amino acids synthesized from essential amino acids. If not enough of the essential amino acid is present to create a semi-essential amino acid, then the essential amino acid stays an essential amino acid.
*Sufficient amounts of the precursor must be fed to achieve this.
14
Q
What are the two semi-essential amino acids.
A
- Tyrosine.
- Cysteine.
15
Q
What is tyrosine synthesized from?
A
Phenylalanine.
16
Q
What is cysteine synthesized from?
A
Methionine.
17
Q
What are conditionally essential amino acids?
A
When the synthesis rate of a non-essential amino acid is lower than the demand for it, the non-essential amino acid becomes an essential amino acid.
18
Q
What are conditionally essential amino acid associated with?
A
Disease state and an immune response.
19
Q
Where does digestion begin?
A
In the stomach.
20
Q
What is released when food enters the stomach?
A
- HCL.
- Pepsin.
21
Q
What does HCL do to protein?
A
Denatures it.
22
Q
What is pepsinogen?
A
The inactive form of pepsin secreted by chief cells.
23
Q
What is pepsinogen activated by?
A
HCL.
24
Q
What does pepsin do?
A
Breaks protein into large peptides.
25
Why is pepsin kept in an inactive form in chief cells?
To prevent the chief cells from being digested.
26
What is secreted when chyme enters the small intestine?
CCK.
27
What does CCK cause to be secreted by the pancreas?
1. Trypsinogen.
2. Chymotrypsinogen.
3. Procarboxypeptidase.
28
What is trypsinogen activated by?
Enterokinase.
29
What is enterokinase?
An enzyme located at the brush border.
30
What is the function of trypsin?
1. Breaks large peptides into small peptides.
2. Activating chymotrypsinogen and procarboxypeptidase.
31
What is the function of chymotrypsin?
Break large peptides into small peptides.
32
What is the function of carboxypeptidase?
Break large peptides into small peptides.
33
What is the more specific term for small peptides?
Oligopeptides (10 or less amino acids).
34
What are aminopeptidases?
Enzymes on the brush border that break down small peptides into tri-peptides, di-peptides, and free amino acids.
35
What does protein digestion look like in ruminant animals?
The microbes in the rumen breakdown proteins and synthesize microbial proteins using the amino acids from the dietary proteins. These proteins leave the rumen to be digested and absorbed in the abomasum and small intestine.
36
What is undegraded crude protein (UDP)?
What protein becomes when it is fed in a small enough amount that it passes through the rumen.
*Similar process to bypass proteins.
37
What happens after the formation of tri-peptides, di-peptides, and free amino acids?
Amino acid transporters transport amino acids into epithelial cells.
38
What are the two types of amino acid transporters?
1. Na+ dependent.
2. Na+ independent.
39
How does an Na+ dependent amino acid transporter function?
It transports an amino acid (normally charged) and a Na+ simultaneously into the cell, acting as a symporter.
40
How does an Na+ independent amino acid transporter function?
It transports only the amino acid into the cell, acting as a uniporter.
41
What is the function of peptide transporters?
To transport di- and tri-peptides into the cell, accompanied by an H+. Acts as a symporter.
42
What happens once the di-and tri-peptides enter the cell?
Intracellular aminopeptidases break them into free amino acids.
43
What happens once the di-and tri-peptides have been broken into free amino acids?
The amino acids leave the cell via amino acid transporters and enter the hepatic portal system.
44
What are the functions of protein in the body?
1. Maintain body structure.
2. Facilitate mobility.
3. Transport.
4. Metabolism.
5. Regulation.
6. Immune function.
*TRIMMS
45
What is the maintain body structure function referring to?
Protein in every cell in the body and protein in collagen.
46
What is the facilitate mobility function referring to?
Muscle.
47
What is the transport function referring to?
Carrier proteins, amino acid transporters, hemoglobin, and GLUT.
48
What is the metabolism function referring to?
Enzymes.
49
What is the regulation function referring to?
All enzymes, most hormones.
50
What is the immune function referring to?
Receptors, antibodies,
51
How is nitrogen balance determined?
Comparing nitrogen intake (diet) to nitrogen excretion (urine + feces).
52
When is nitrogen equilibrium attained?
Maintenance.
53
When is a positive nitrogen balance (higher input that output) attained?
1. Growth.
2. Athletic training.
3. Production.
4. Gestation.
54
When is a negative nitrogen balance (higher output than input) attained?
1. Starvation.
2. Certain diseases.
55
Why is nitrogen balance not the best measurement of protein intake?
1. Is non-specific. Measures all nitrogen, not just what is found in protein, peptides, and amino acids.
2. Amino acids can be synthesized in the body, meaning that nitrogen excretion may be slightly higher than intake, even if the animal is not diseased or starving.
56
What is dynamic protein turnover?
The continuous degradation and resynthesis of proteins in the body.
57
What are amino acids used for in the body?
1. Protein synthesis.
2. Oxidized in the liver to form reactants in other bodily processes.
3. Synthesis of non-protein metabolites (ex: Hormones).
58
What are the two steps of protein synthesis (be very basic with this)?
1. Transcription (DNA--->RNA).
2. Translation (RNA--->Protein).
59
What is required for protein degradation?
1. The cell marks the protein that needs to be degraded.
2. Intracellular proteases* degrade the marked proteins.
*Also found in lysosomes.
60
What are the two categories that amino acids (with exceptions) fall into when oxidized?
1. Glucogenic.
2. Ketogenic.
61
What do glucogenic amino acids become when oxidized?
1. Glycolytic intermediates (used in glycolysis).
2. Citric acid cycle intermediates.
62
What are the glucogenic amino acids?
1. Alanine.
2. Valine.
3. Arginine.
4. Threonine.
5. Aspartate.
6. Serine.
7. Asparagine.
8. Proline.
9. Cysteine.
10. Methionine.
11. Glycine.
12. Histidine.
13. Glutamate.
14. Glutamine.
63
What do ketogenic amino acids become when oxidized?
Acetyl-CoA.
64
What is the acetyl-CoA produced from ketogenic amino acids used for?
1. Ketone body synthesis.
2. Fatty acid synthesis.
65
What are the ketogenic amino acids?
1. Lysine.
2. Leucine.
66
What amino acids are both glucogenic and ketogenic?
1. Tryptophan.
2. Tyrosine.
3. Phenylalanine.
4. Isoleucine.
67
What are the 3 ways nitrogen can be excreted?
1. Ammonia.
2. Urea.
3. Uric acid.
68
What animals excrete nitrogen in the form of ammonia and how do they do it?
1. Aquatic invertebrates and most bony fish.
2. Through the gills.
69
What animals excrete nitrogen in the form of urea and how do they do it?
1. Mammals, most amphibians, cartilaginous fish.
2. Urination, through the skin, through the gills, or a combination of both.
*Stored with water in the bladder.
70
What animals excrete nitrogen in the form of uric acid and how do they do it?
1. Birds, insects, reptiles.
2. In the form of urine, a urine-like substance, or feces.
*Incomplete urea cycle.
71
What are the non-protein functions of amino acids?
1. Nitric oxide.
2. Coenzyme A (CoA).
3. Creatine.
4. Thyroid hormone.
5. Choline.
6. NAD.
7. Histamine.
8. Melatonin.
9. Taurine.
10. Carnitine.
11. Glutathione.
72
What amino acid is nitric oxide synthesized from?
Arginine.
73
What is nitric oxide used for?
Vasodilation.
74
What amino acid is creatine synthesized from?
Arginine.
75
What is creatine used for?
ATP storage in the muscles.
76
What amino acid is choline synthesized from?
Serine.
77
What is choline used for?
1. Acetylcholine
2. Phospholipids.
78
What amino acid is histamine synthesized from?
Histidine.
79
What is histamine used for?
To increase membrane permeability.
80
What amino acid is taurine synthesized from?
Cysteine.
81
What is taurine used for?
1. Cardiovascular health.
2. Vision health.
*Essential in the diet of cats, which cannot synthesize it. .
82
What amino acid is glutathione synthesized from?
Cysteine.
83
What is glutathione used for?
Antioxidants.
84
What amino acid is coenzyme A synthesized from?
Cysteine.
85
What is coenzyme A used for?
Bodily reactions.
86
What amino acid is thyroid hormone synthesized from?
Tyrosine.
87
What is thyroid hormone used for?
Metabolism and body temperature regulation.
88
What amino acid is NAD synthesized from?
Tryptophan.
89
What is NAD used for?
Cofactor in reactions.
90
What amino acid is melatonin synthesized from?
Tryptophan.
91
What is melatonin used for?
Circadian rhythm and sleep regulation.
92
What amino acid is carnitine synthesized from?
Lysine.
93
What is carnitine used for?
Beta-oxidation.
94
What is the minimum % protein a protein source must have?
20%.
95
What are oilseed meals?
The by-products of vegetable oil production.
96
What is the the most important protein supplement for livestock feeding?
Soybean meal.
97
What 3 deleterious factors are associated with soybean meal?
1. Protease inhibitors.
2. Lectins.
3. Goitrogens.
98
What do protease inhibitors do?
Stop protein digestion, particularly the enzyme trypsin.
*Can lead to pancreatic hypertrophy.
99
What do lectins do?
Bind carbohydrates at the brush border, causing digestive disturbances.
99
What do goitrogens do?
Inhibit thyroid hormone production, causing goiter (from a build-up of incomplete thyroid hormone in the thyroid).
100
How are the deleterious factors in soybean meal inhibited?
Soaking the soybean meal in chemicals or heat treating the soybean meal.
101
What is the CP concentration of soybean meal?
44-50% (AF basis).
102
What is the quality of the protein in soybean meal?
High.
*Low fiber.
103
What phosphorous binding substance does soybean meal contain?
Phytate.
*Why soybean meal is fed with phytase.
104
What is the second most important plant protein supplement?
Cottonseed meal.
*Fed more to ruminants.
105
What deleterious factor is associated with cottonseed meal?
Gossypol.
106
What does gossypol do?
Binds iron and inhibits iron metabolism, causing reduced growth, reduced feed intake, heart damage, lung damage, liver damage, and anemia.
*Green egg yolks in hens.
107
What is the CP concentration of whole cottonseed?
23% CP.
108
What is the lipid concentration of whole cottonseed?
23% fat.
109
What is the CF concentration of whole cottonseed?
17% CF.
110
What is the CP concentration of cottonseed meal?
41% CP.
111
What is the CF concentration of cottonseed meal?
12% CF.
112
What type of fatty acids does cottonseed oil contain?
Cyclopropene.
113
What do cyclopropene fatty acids inhibit?
Inhibits desaturase, leading to the accumulation of hard fat in the muscle (especially in non-ruminants).
*Pink egg albumen in poultry.
114
What are the 3 animal protein sources?
1. Meat meal.
2. Blood meal.
3. Blood + meat meal.
*Mostly fed to companion animals.
115
What type of protein is in animal protein sources?
High quality.
*Contains vitamin B12 as well.
116
What are the 2 safety concerns associated with animal protein sources?
-E.coli.
-Salmonella.
117
What are non-protein nitrogen (NPN) sources converted to in the rumen?
To ammonia by the microbes during amino acid synthesis.
118
What is the most common NPN source?
Urea.
119
Why must urea be fed in small (<2% of diet) amounts?
To prevent urea toxicity.
120
What is urea toxicity characterized by?
1. Labored breathing.
2. Slobbering.
3. Ataxia.
4. Labored breathing.
121
What are 2 other common NPN sources?
1. Biuret.
2. Dried poultry waste.
122
What is biuret?
2 ureas combined.
123
Why is biuret used?
Is converted slower to ammonia than urea.
*Takes about 6 weeks of continuous exposure before the proper enzymes are produced.
124
What is dried poultry waste?
Manure + litter from poultry houses.
*Low concentration in food and high in uric acid.
125
Why should dried poultry litter not be fed to sheep?
Due to copper sulfate being used as an anti-parasitic in chickens, sheep are sensitive to copper.
