Transcript Document

Proteins
• Large molecules that supply amino acids
and nitrogen
• aa-aa-aa - is a peptide (link)
• Each group of aa is a polypeptide
• One or more polypeptide chains is a protein
Amino Acids and Proteins
• Amino acids are defined as any organic
compound containing both an amino and a
carboxyl group.
Proteins
• Amino acids are called the building blocks of
protein.
• Proteins are essential to all living cells.
• Protein functions include:
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Regulation of metabolism
Cell membrane construction-hair, skin, nails
Muscle fiber formation, contraction regulation
Tissue growth and repair
• Proteins also serve as enzymes, hormones, and
antibodies.
Proteins are sometimes bound to other
substances to form even more complex
molecules. For example:
Proteins conjugated with carbohydrates are
called glycoproteins
Proteins conjugated with fats are called
lipoproteins
Proteins/Amino Acids
• They are not stored in the body like fat and
carbs. If not consumed in required levels,
breakdown of protein in the viscera and
skeletal muscle will occur. This breakdown
in protein provides amino acids for energy.
The breakdown of circulating and structural
protein into glucose is called
gluconeogenesis.
Recommended Requirements
• Protein requirements p. 298 table 9-5
Factors affecting protein requirement
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Protein quality
Amino Acid Composition
Digestibility
Energy Density
• There are several tests that predict the
quality of protein.
• * This information can be found in table 9 – 6 on page 299
• Net protein utilization (NPU): This
compares the amino acids composition to a
source known to be of a very high quality.
Egg protein is typically used as the
reference protein as it has been given a
chemical score of 100.
• Amino acid score (AAS): This test
measures the contribution a protein makes
to all of the essential amino acids. This test
is a modification of the chemical score test
• Protein efficiency ratio (PER): This is the
simplest and most commonly used test.
Weanling male rats or growing chicks are
fed an adequate diet containing the test
protein for 28 days and changes in weight
are measured. PER is calculated by the
amount of weight gained divided by the
total grams of protein consumed.
• Biological Value: This is the percentage of
absorbed protein retained in the body. It is
a measure of the ability of the body to
convert absorbed amino acids into body
tissue. Nitrogen in the food is measured
against the nitrogen in the feces and urine.
Protein Values
• High quality protein is especially needed
during:
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Periods of growth
Physical exertion
Pregnancy
Lactation
Repair of damaged tissues
Signs of Protein Deficiency
• Decrease of muscle
mass
• Weight loss
• Dull hair coat
• Anorexia
• Immunodeficiency
• Generalized edema
• Death
Felines
• Cats are specifically adapted for a high protein,
low carb diet. They depend on gluconeogenesis as
a major source of energy. Cat’s are limited in their
ability to conserve protein due to continuous
protein catabolism.
• Metabolism of excess amino acids increases liver
and kidney overload.
Amino acids occur naturally in plant and animal tissue
and are the chief constituents of protein. Amino acids are
broken down into two groups, Essential Amino acids
and Nonessential amino acids.
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Page 297
Deficiencies of even one of the amino acids can
have grave consequences.
For example:
Arginine deficiency causes a build up of ammonia
in the bloodstream, causing vomiting in dogs and
death in cats.
Methionine and Cysteine deficiencies cause weight
loss and skin disorders
Taurine deficiency in cats leads to blindness and
heart failure.
This information is found on page 298
Specific Nutrient Related
Diseases
• Hepatic Lipodosis
• Diabetes Melllitus
Cont. Felines
• Due to the dependency on gluconeogenesis,
the feline has very little energy in reserve. If
a cat becomes anorexic for any period of
time, the body has little or no protein to
breakdown for energy. Instead it breaks
down fat. The fat accumulates in the liver
causing acute liver failure, a condition
called hepatic lipidosis (fatty liver disease).
Ketosis
• Primarily occurs in animals with diabetes mellitus. A
deficiency of insulin prevents the animal from utilizing
the glucose circulating in the blood stream. Insulin is
needed to get glucose to enter the body cells,
consequently the animal breaks down fat for energy.
Excessive amounts of acetyl-Coa (product A) starts to
accumulate in the blood. Accumulated product A is
converted to Ketone Bodies, large amounts of ketone
bodies cause a condition called ketoacidosis. Ketosis is
life threatening because ketone bodies are acidic and
the body can not function when the blood drops below
a pH of 7.35.
National Exam note:
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Normal Animal = blood pH 7.4
If pH rises above 7.45 = alkalosis
If pH goes below 7.35 = acidosis
Normal range pH of blood: 7.35 – 7.45