All protein is composed of building units (composed of nitrogen) called?
Amino acids
Each amino acid is joined by a?
Peptide bond
How many common amino acids have been identified?
20
Nine amino acids that must be obtained from the diet because the body does not make adequate amounts to support body needs?
Indispenable amino acids
Five amino acids that the body can synthesize from other amino acids supplied through the diet and thus do not have to be consumed on a daily basis?
Dispensable (not necessary) amino acids
Six amino acids that become indispensable in the diet under certain circumstances such as illness?
Conditionally indispensble amino acids
Genetic disorder in which the affected individual lacks the enzyme need to convert phenylalanine to tyrosine?
Phenylketonuria (PKU)
Relative intake and output of substances in the body to maintain equilibrium necessary for health in various circumstances throughout life?
Balance
A process where the body's tissue proteins are constantly being broken down into amino acids?
Catabolism
A process where the body's tissue proteins are resynthesized into tissue proteins as needed?
Anabolism
The body's nitrogen balance indicates how well?
Its tissues are being maintained
The intake and use of dietary protein is measured by the amount of?
Nitrogen intake in food protein and the amount of nitrogen excreted in urine output
A positive nitrogen balance exists when...
the body takes in more nitrogen than it excretes, thus building tissue
Failure to maintain nitrogen balance may not become apparent for some time until eventual loss of?
muscle tissue, impairment of body organs and functions, and increased susceptibility to infection
Body protein, such as the lean mass of muscles, accounts for apprx.?
Three fourths of the dry matter in most tissues, excluding bone and adipose fat
Protein makes up the bulk of?
Muscles, internal organs, brain, nerves, skin, hair, and nails
What are the primary functions of protein?
Repair worn-out, wasted, or damaged tissue and build new tissue
In times of need, protein is used only as a backup source in order to?
Furnish additional fuel to sustain body heat and energy
Because water is attracted to protein, plasma proteins such as albumin...
help control water balance throughout the body by exerting osmotic pressure, which maintains normal circulation of tissue fluids within the appropriate compartments
What aids in the metabolic functions through enzymes, transport agents, and hormones?
Protein
What proteins control metabolic processes?
Digestive and cell enzymes
What is necessary for the digestion of carbohydrates (amylase), fat (lipase), and proteins (proteases) which are all protein in nature?
Enzymes
These act as vehicles in which nutrients are carried throughout the body?
Proteins
Protein is used to build special white blood cells (lymphocytes) and antibiodies as part of the body's immune system to help?
defend against disease and infection
What are the sources of complete proteins?
Primarily animal origin (egg, milk, cheese, poultry, and fish), and soybeans/soybean products
What are sources of incomplete protein?
Generally plant origin (grains, legumes, nuts, seeds)
A mixture of plant proteins can provide adequate amounts of amino acids when the vegetarian diet contains?
Soybeans and other dried legume proteins (i.e. beans and peas)
What are Lacto-ovo-vegetarians?
Follow a food pattern that allows dairy products and eggs, excludes meat and fish
What are Lacto-vegetarians?
Accept only dairy products from animal sources, but no eggs, and excludes meat or fish
What are Ovo-vegetarians?
Only animal product consumed is eggs
Vegans consume?
No animal products
What are the key nutrients of concern for vegetarians?
Protein, iron, zinc, calcium, vitamin D, vitamin B12, vitamin A, and omega-3 fatty acids
All enzymes used for protein digestion in the stomach are stored as?
Inactive proenzymes called zymogens
Enzymes needed for protein digestion cannot be...
stored in an active form or the cells and organs that produce and store them would be digested
What medium helps convert pepsinogen to active pepsin, the gastric enzyme specific to proteins?
Hydrocholoric acid
What is the main gastric enzyme specific for proteins, activated by hydrochloric acid?
Pepsin
What is the gastric enzyme only present in infancy that helps prevent food from passing rapidly from stomach to small intestine?
Rennin
What three enzymes are produced by the pancreas for the breakdown of protein?
Trypsin, chymotrypsin, and carboxypeptidase
Trypsin is activated by what enzyme?
Enterokinase, which produces polypeptides and dipeptides
What enzyme is secreted by pancreas and activated by trypsin, breaking proteins down into polypeptides and dipeptides?
Chymotrypsin
Protein-splitting enzyme activated by trypsin that breaks down protein into peptides and free amino acids?
Carboxypeptidase
What enzymes are secreted by the small intestine to complete the breakdown of proteins into amino acids?
Aminopeptidase and dipeptidase
What three factors influence the requirement for protein?
1) Tissue growth
2) Quality of dietary protein
3) Additional needs from illness or disease
When the body has an illness or disease, there is an increased need for?
Proteins and kilocalories, in rebuilding tissue and meeting the demands of an increased metabolic rate
When enough protein intake has been consumed, what happens to additional protein?
It is stored as fat or used as energy; it does not build muscle
What is the primary function of dietary protein?
Supply the necessary amino acids to build and repair body tissue
Are healthy adults in a state of nitrogen balance?
Yes
Positive nitrogen balance exists during periods of rapid growth (e.g. in infancy and adolescene)?
True
When negative nitrogen balance exists...
An individual is less able to resist infection and general health deteriorates
Egg protein has a higher biologic value than...
meat protein
Nine of the 20 amino acids are indispensable, meaning that?
the body cannot make them and must obtain them from the diet
A complete protein food of high biologic value contains?
All nine of the indispensable amino acids in correct proportion to meet human requirements
A state of negative nitrogen balance may occur during periods of?
