- essential throughout the entire lifespan.
- basic material of every body cell
- Of the six nutrient groups, this only can make new cells and rebuild tissue.
- the only nutrient group that contains nitrogen.
Protein
Functions of Protein
2 Building and repairing body tissue
- Provision of the correct type and number of amino acids
- During catabolism, amino acids are recycled to build new tissues (anabolism)
Functions of Protein
3 Regulating body functions
- Metabolism and digestion
- Fluid and electrolyte balance
- Development of antibodies
3rd Function of Protein
Providing energy
two essential amino acid that develop during childhood only
Arginine and histidine
type of proteins
- High biologic value
- Contains all essential amino acids
- Extremely bioavailable
Complete
type of proteins
- Lacks one or more amino acids
- Cannot build tissue without help of other proteins
- Plant source
Incomplete
type of proteins
*Occur when a combination of incomplete proteins are eaten in the same day to make a complete protein
*Animal source
Examples: corn and beans, rice and beans, bread and peanut butter, bread and split pea soup, bread and cheese, bread and baked beans, macaroni and cheese, cereal and milk
Complementary proteins
Food Sources
- Complete proteins.
- Meats, fish, poultry, eggs, milk, and cheese
- Provides saturated fats and cholesterol
Animal food sources
Food Sources
- Incomplete proteins
- Corn, grain, nuts, sunflower seeds, sesame seeds, and legumes (soy beans & peanuts)
Plant food sources
Food Sources
- Textured soy protein and tofu
- Meat alternatives made from soy protein and other ingredients to simulate various kinds of meat, B Vitamins
Analogues
Food Source
* Excellent source of protein, iron and b vitamins
* tofu is a soft, cheeselike, bland food made from soy milk, low in sodium,
* Helpful to strict vegetarians to meet their protein needs
Analogues
Mechanical digestion of proteins starts at?
begins in mouth
protein chem digestion begins in?
stomach
The enzyme ___ reduces proteins to polypeptides.
pepsin
10 or more amino acids bonded together
- Polypeptides
Amino acids are broken down and the nitrogen-containing [amine group is stripped off]
deamination
In the small intestine, three pancreatic enzymes _ _ _ continue chemical digestion and absorption through the villi
trypsin, chymotrypsin, and carboxypeptidase
- Amino acids are broken down and the nitrogen-containing amine group is stripped off (deamination).
- Ammonia is produced.
- Liver picks up ammonia and converts it to urea.
- Kidney filters out urea and excretes it.
- Remaining parts are used for energy or converted to carbohydrate or fat and stored as glycogen or adipose tissue
- Amino acids are broken down and the nitrogen-containing amine group is stripped off (deamination).
- Ammonia is produced.
- Liver picks up ammonia and converts it to urea.
- Kidney filters out urea and excretes it.
- Remaining parts are used for energy or converted to carbohydrate or fat and stored as glycogen or adipose tissue
the average daily requirement of protein for each kilogram of body weight
0.8 g
Connection to colon cancer and high calcium excretion leading to ___
osteoporisis
National Research Council recommends that protein intake represent no more than how many percent?
15-20%
exists when more nitrogen is lost than taken in.
- E.g. fever, burns
Negative nitrogen balance
exists when nitrogen intake exceeds amount excreted
- It indicates new tissues are being formed
Positive nitrogen balance
