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43 Cards in this Set
- Front
- Back
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Protein Quality is dependent upon which two things?
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Essential Amino Acid content and digestibility
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Types of ways to evaluate of protein quality include...
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- Amino Acid Chemical Score
- Protein Efficiency Ratio - Biological Value - Net Protein Utilization |
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What is the Amino Acid score?
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It is an amino acid composition of a food compared to a reference protein (such as an egg white). The lowest score will identify the limiting amino acid.
Ex: An AA of 70% of reference gets a score of 70. |
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What is the Amino Acid Score Equation?
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Content of each indispensable AA in food protein (mg/g) divided by content of same AA in reference protein (mg/g)
x 100 = score % |
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What is the Protein Efficiency Ratio (PER)?
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It measures weight gain of a growing animal and compares it to the animal's protein intake. A limitation includes that we do not know what king of weight is gained (ie: weight from fat or weight from muscle?)
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What is the Protein Efficiency Ratio equation?
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PER = gain in BW (g) divided by the protein consumed (g)
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What is the Biological Value measurement (BV)?
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It measures efficiency in supporting body's needs. A given protein is fed as a sole protein in a diet and nitrogen retention is measured from a given amount of nitrogen absorbed. Ex: A BV of 100 means 100% retention.
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What is the Biological Value equation?
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BV = nitrogen retained/nitrogen absorbed x 100 = %
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What is Net Protein Utilization (NPU)?
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It is the amount of nitrogen retained from a given amount eaten.
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What is the equation for Net Protein Utilization?
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NPU = nitrogen retained/nitrogen consumed x 100 = %
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What is Nitrogen Balance?
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It is nitrogen input VS nitrogen output
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What percent of protein is roughly made up of nitrogen?
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16%
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What is nitrogen equilibrium?
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nitrogen input = nitrogen output
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What is positive nitrogen balance?
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Nitrogen input is greater than nitrogen output. Therefore, one is retaining more than excreting.
Ex: infants, children, pregnant women, weight lifters. |
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If a person eats 80 g of protein, how many g of that is nitrogen?
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Nitrogen is 16% of protein.
.16 x 80g = 12.8g nitrogen OR 80/6.25 = 12.8 |
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If a person consumed 10 grams of nitrogen, how much protein did they eat?
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(OPPOSITE)
10 x 6.25 = 62.5 grams of protein |
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What is negative nitrogen balance?
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Nitrogen input is less than nitrogen output.
Therefore, losses exceed intake. Ex: burns, injury, infection. |
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Proteins starts what during digestion?
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A polypeptide.
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What kind of digestion occurs in the mouth?
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Not chemical, only mechanical where polypeptides may be cleaved into smaller peptides.
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What kind of digestion occurs in the stomach?
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HCl and GRP will denature proteins by unraveling them into quaternary, tertiary, secondary proteins but NOT primary because that is technically a sole AA chain.
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Where is HCl secreted from?
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The parietal cells in the stomach with gastrin (hormone).
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GRP is what?
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A neuropeptide.
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What activates pepsinogen?
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HCl will activate pepsinogen to pepsin.
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HCl will also do what in the stomach?
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Kill bacteria because of high acidity.
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What are the end products of stomach digestion?
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- Smaller peptides
- Oligopeptides - Free AA (strictly from mechanical digestion) |
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What is an endopeptidase?
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An endopeptidase will cleave amino acids WITHIN a polypeptide.
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What is an exopeptidase?
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An exopeptidase will cleave amino acids off the END of the polypeptide.
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What is the role of endopeptidases and exopeptidases?
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To break down protein.
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What are the two sides of a protein?
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The N-Terminal and the C-Terminal.
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What kind of secretions start protein digestion in the small intestine?
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Secretin and CCK is released, which go to the acinar cells of the pancreas where
- Trypsinogen - Chymotrypsinogen - Procarboxypeptidase - Proelastase (connective tissue) - Collagenase (connective tissue) are released into the Sphincter of Oddi. |
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How is trypsinogen activated?
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Enteropeptidase will activate trypsinogen into trypsin, which is an endopeptidase. Enteropeptidase is a brush border enzyme and is also an endopeptidase.
Trypsinogen is ALSO activated by trypsin, itself. |
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What regulates the STOP & GO process of the activation of these enzymes?
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Negative feedback, triggered by increase of trypsin which will slow down zymogen secretion from the pancreas.
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How is chymotrypsinogen activated?
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Trypsin will activate chymotripsinogen to chymotrypsin, which is an endopeptidase.
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How is procarboxypeptidase A and B activated?
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Trypsin will activate procarboxypeptidase A and B to carboxypeptidase A and B, which are exopeptidases. This mechanism is ZINC dependent and will work at the C-terminal end.
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What enzymes will break down oligopeptides at the N terminal at the brush border?
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Aminopeptidases, dipeptidases, tripeptidases.
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What are the end products of protein digestion at the end of the lumen of the SI heading into the enterocyte?
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Dipeptides, tripeptides, (both consisting of 2/3rds of the absorption) and free amino acids (1/3 of the absorption).
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What do all amino acids need in order to cross over from the SI lumen into the enterocyte?
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A "Carrier".
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Which carriers are sodium dependent?
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All uppercase letters other than "L".
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Which carriers are sodium independent?
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All lowercase letters plus "L".
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T/F Amino Acids compete for carriers.
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TRUE.
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What protein components are absorbed the fastest?
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Essential amino acids are absorbed faster than nonessential amino acids.
Peptides are absorbed faster than individual amino acids. |
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What are some fates of Amino Acids within the enterocyte?
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- Oxidized for energy : glutamine
- Made into apoprotein - Make digestive enzymes - Make hormones - Make nitrogen containing compounds |
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How do amino acids passed into the Basal Lateral Membrane (blood)?
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Either diffusion or sodium independent transport with normal AA in the gut, whereas sodium dependent transport will happen with low AA in the gut.
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