Proteins Flashcards
6 Nutrient Classes
Water Carbohydrates Proteins Lipids Vitamins Minerals
6 roles/functions of Proteins
- ) Structural elements (hair, wool, collagen, muscle)
- ) Enzymes
- ) Hormones
- ) Carriers in the blood (hemoglobin)
- ) Associated with genes (hereditary factors)
- ) Antibodies
In protein digestion, the digesting enzymes are secreted as…?
Inactive Zymogens
What is the principle protein-digesting enzyme in the stomach (abomasum in ruminants)?
Pepsin
What activates the inactive zymogen into this active enzyme?
HCl
What is the distinction between an endopeptidase and an exopeptidase?
- Endopeptidase attacks internal peptide bonds
- Exopeptidase attacks terminal peptide bonds
Name some examples of an exopeptidase.
- Carboxypeptidase
- A&B
- Aminopeptidase
- Dipeptidase
10 amino acids classified as dietary essentials for pigs, rats, dogs, and growing humans.
Phenylalanine Valine Tryptophan Threonine Isoleucine Methionine Histidine Arginine Lysine Leucine
If you were feeding a diet of poor amino acid balance to a growing nonruminant animal, would you expect the blood urea level to be higher, lower, or the same as that of an animal fed a diet of perfect amino acid balance for muscle growth?
What would you expect if the animal was a ruminant?
Higher
The same results
The linkage between one amino acid and another in a protein…?
Peptide bond
Protein quality of the diet is a function of WHAT aspects of the amino acid in that protein?
Qualitative (Balance)
Quantitative (Total Amount)
Name the physiological process that is a protein quality that is extremely critical to the biological value of a protein.
Rate and Extent of Digestion/Absorption
What two amino acids has it been shown that man does not need for maintenance? What about for growing?
- Maintenance: Histidine and Arginine NOT NEEDED
- Growing: need all 10
Proteins comprise about ____ of the dry, fat-free body.
80%
Name the elements that protein contains? (5)
C, H, O, N, S
The N content in protein content of tissues and feedstuffs? (%)
14-20% (Avg. 16%)
These yield ONLY amino acids or their derivatives on hydrolysis. (5)
Simple proteins:
- Albumin
- Globulin
- Albuminoids
- Histones
- Protamins
Simple proteins combined with a non-protein radical…?
Conjugated proteins
There are 5 conjugated proteins. They are…?
- ) Nucleoproteins
- ) Glycoproteins
- ) Phosphoproteins
- ) Metalloproteins
- ) Lipoproteins
Nucleoprotein
1 or more protein molecules with NUCLEIC ACID
Glycoprotein
Protein molecule & substance(s) containing CHO group (ex: mucin in saliva)
Phosphoprotein
Protein molecule & a P containing substance other than a nucleic acid (ex: casein)
Metalloprotein
Protein molecule and a METAL (ex: cytochrome oxidase (Cu))
Lipoprotein
Protein molecule & a LIPID (ex: VLDL)
Consist of altered and degraded products of naturally occuring proteins – produced by action of heat, enzymes or chemical agents
Derived proteins
Non-protein Nitrogen Compounds
Not all of the N present in palnts, feeds or tissues are in the form of protein.
A portion may be non-protein such as:
-amides, amino acids, nitrogenous glucosides and fats, alkaloids and ammonium salts
The end product of protein digestion (hydrolysis)/ building blocks for body protein
Amino Acids
Aliphatic AAs. Name the 4 subcategories
- ) Monoamino-monocarboxylic acids - neutral AAs
- ) Monoamino-dicarboxylic acids - acidic AAs
- ) Diamino-monocarboxylic acids - basic AAs
- ) Sulfu-containing AAs
3 Types of AAs
Aliphatic, Aromatic, Heterocyclic
Amino acids are _______.
Amphoteric - behave as both an acid and base
A monoamino-monocarboxylic amino acid (ex: glycine) exists as a dipolar ion…
- “Zwitterion” where both acidic and basic groups are IONIZED and the molecule is electrically NEUTRAL.
- Said to be ISOELECTRIC
The 1840’s showed that all proteins are not of equal value and revealed that…
Gelatin would not take the place of meat protein in the diet
In the period of 1870-1900, scientists proposed that…
Amino acids were probably the building blocks of protein
In the early 1900’s, many workers began to make use of…
The purified diet technique to study the effects of a single source of dietary protein on N balance and growth
-Mendel and Osborne
The most critical understanding of protein nutrition resulted from the studies of…
W.C. Rose in the 1930’s
W.C. Rose and his Illinois coworkers were able to…
Classify the 10 amino acids as dietary essentials
Name the AAs that are NOT synthesized in animal tissue.
The 10 essential amino acids
The AAs synthesized from limited substrates (2)
Tyrosine (phenylalanine)
Cystine (methionine)
The AAs readily synthesized by animal tissue (9)
Glycine Alanine Serine Glutamic acid Aspartic acid Proline Hydroxyproline Asparagine Glutamine
How many essential AAs are there for poultry?
12 Essential AAs, the extra 2 are:
- Glycine
- Serine
“Sparing Effect” on the requirements for other AAs
- Cystine can meet requirement of methionine+cystine
- Tyrosine can meet requirement of phenylalanine+tyrosine
In metabolism there is no such thing as…
A nonessential amino acid
Plants can synthesize all te AAs found in nature by their capacity to… and their ability to…
- Utilize ammonia
- Fabricate the carbon structures (skeletons) to each AAs
Mammals LACK the ability to..
Make about 1/2 the carbon structures and their AAs that plants can make
Two aspects of protein nutrition/quality are of concern:
- ) Qualitative Phase - balance
2. ) Quantitative Phase - gross amount
If there is a marked lag in the digestion of an AA, _________ is reduced due to the “________” for protein synthesis.
-Protein quality is reduced due to the “time factor” for protein synthesis
Name the aromatic amino acid to which iodine is added to make T4
Tyrosine
The group of amino acids in relatively greater need in poultry due to their high content in feathers.
S-containing AAs
Name 3 basic amino acids
- Lysine
- Arginine
- Citrulline
When amino acids are present in excess, the excess is catabolized for the energy in the carbon skeleton and the nitrogen is excreted. In what form is the nitrogen excreted in mammals?
Urea
Name 3 factors affecting microbial protein synthesis
- Available energy
- Available nitrogen
- Available other nutrients (BCFA, S, Co, Fe)
What activates the inactive zymogen pepsinogen into the active pepsin in the stomach?
HCl
What activates the inactive zymogen trypsinogen into the active trypsin in the small intestine?
Enterokinase
Name some examples of an endopeptidase.
Trypsin, Chymotrypsin, Pepsin, Enterokinase
The formula for True Biological Value is…
[NI - (FN-MFN)] - (UN-EUN) / [NI-(FN-MFN)] x 100 = B.V.
OR
(true N absorbed) - (true urinary N) / (true N absorbed) x 100 = B.V.
What is Biological Value?
Measures how well the N absorbed is used; % of digested N that is utilized
A pig consumes 4 kg of a ration containing 15% crude protein. It excretes 1000 gm of feces containing 20% crude protein.
What is the CONSUMED N?
Consumed N (g) = 4000g 15%16% = 96g
A pig consumes 4 kg of a ration containing 15% crude protein. It excretes 1000 gm of feces containing 20% crude protein.
What is the FECAL NITROGEN?
Fecal N (g) = 1000g20%16% = 32g
A pig consumes 4 kg of a ration containing 15% crude protein. It excretes 1000 gm of feces containing 20% crude protein.
Urinary N = 63 g
Metabolic Fecal N = 6 g
Endogenous Urinary N = 2 g
Fecal N = 32 g
Consumed N = 96 g
What is the TRUE DIGESTIBILITY COEFFICIENT (DC)?
True Digestibility Coefficient = (96-(32-6)) / 96 = 72.92%
Formula: (Consumed N - (Fecal N - Metabolic Fecal N)) / (Consumed N) x 100
A pig consumes 4 kg of a ration containing 15% crude protein. It excretes 1000 gm of feces containing 20% crude protein. Urinary N = 63 g Metabolic Fecal N = 6 g Endogenous Urinary N = 2 g Fecal N = 32 g Consumed N = 96 g What is the NITROGEN RETENTION?
Nitrogen Retention = 96-(32+63)= 1g/d
Formula: Consumed N - (Fecal N + Urinary N) = NR
A pig consumes 4 kg of a ration containing 15% crude protein. It excretes 1000 gm of feces containing 20% crude protein. Urinary N = 63 g Metabolic Fecal N = 6 g Endogenous Urinary N = 2 g Fecal N = 32 g Consumed N = 96 g What is the BIOLOGICAL VALUE?
Biological Value = ((96-(32-6))-(63-2)) / (96-(32-6)) = 12.86%
(Formula: ((Consumed N - (Fecal N - Metabolic Fecal N))-(Urinary-Endogenous Urinary N)) / (Consumed N - (Fecal N-Metabolic Fecal N)) = BV)
Apparent Digestibility Coefficient Formula (Apparent DC)
(NI-FN) / NI
True Digestibility Coefficient Formula (True DC)
(NI - [FN-MFN] ) / NI)
Nitrogen Retention Formula
NI - (FN + UN)
Acronyms for evaluating proteins from a nutritional standpoint
EUN = Endogenous urinary nitrogen DC = Digestibility coefficient NI = Nitrogen intake FN = Fecal nitrogen MFN = Metabolic fecal nitrogen
With regard to NPN content of the feedstuff:
Which is higher? Mature or Immature Corn
Immature Corn
With regard to NPN content of the feedstuff:
Which is higher? Fresh-chopped or Ensiled Corn
Ensiled Corn
With regard to NPN utilization:
Which is higher? Increased energy content of the diet or to a low energy diet
Increased Energy Content
With regard to NPN utilization:
Which is higher? Less frequent feeding compared to more frequent feeding
More frequent feeding
With regard to NPN utilization:
Which is higher? High roughage diet compared to a high concentrate diet
High concentrate diet
With regard to N recycling:
Which is higher? Higher dietary crude protein content compared to lower crude protein content.
Lower crude protein content
With regard to the extent of degradation of protein in the rumen.
High or low
High: Increased time that the feed spends in the rumen
With regard to the extent of degradation of protein in the rumen.
Which is higher? A lower rumen pH compared to the normal rumen pH.
Normal rumen pH.
With regard to the extent of degradation of protein in the rumen.
Which is higher? The heat treatment of a protein supplement compared to no heat treatment
No heat treatment
Of the four protein types found in corn, two are very poor quality (zein and glutelin). Name the two primary protein types
Globulin and Albumin
An amino acid which cannot be synthesized at a rate rapid enough to meet the body needs is defined as…
Essential or Indispensable
What dietary compound often fed to ruminants is clearly enhanced the most (given that if it was absorbed directly with no alteration, it would have a BV = 0%)?
NPN or Urea
