What are terms used to classify amino acids in the diet?
Essential, nonessential and conditionally essential
What is classified as conditionally essential when dietary intake of phenylalanine is insufficient or the body cannot normally metabolize phenylalanine.
What is required to bind two molecules of glycine together and to release a molecule of water?
What is the amino acid sequence of a protein referred to?
the order of amino acids in a peptide chain
In comparison to the well-defined structure of starch, what is the most important factor that allows for the synthesis of thousands of different proteins?
the number of different amino acids
What is the process by which heat or acidity disrupts the normal shape of a protein chain?
The application of heat or acid to a protein that causes its shape to change is known as what?
What digestive enzyme would be most affected in people who are unable to produce hydrochloric acid?
what products are absorbed into the circulation after digestion of proteins?
free amino acids, and a few dipeptides and tripeptides
what is the usual fate of orally ingested enzyme supplements?
Digested by gastrointestinal proteases
what are some characteristics of enzymes?
they are all catalysts, they have a protein structure and they can be destroyed by heat.
what are some of the fates of amino acids in the intestinal tract?
some may be used for energy by the intestinal cells, some may be used for synthesis of proteins by the intestinal cells, and they may be transported across the intestinal cell membrane to the capillaries.
The code to make a protein is carried by a strand of messenger RNA is a process of what?
Messenger RNA is constructed from a DNA template to carry instructions is a characteristic of what?
what are some features of protein in nutrition?
the study of the body's proteins in known as proteomics, protein synthesis requires messenger RNA and transfer RNA, and the synthesis of a protein by following the genetic code is known as gene expression.
A common genetic variation which causes a change in the amino acid sequence in the structure of hemoglobin leads to what disease?
what is a characteristic of sickle-cell anemia?
the abnormal structure of the hemoglobin alters the shape of the red blood cell.
what are some associations between protein nutrition and the body's water balance?
inadequate protein intake may lead to edema, insufficient protein synthesis by the liver may lead to edema, and excessive protein intake burdens the kidneys to excrete unused nitrogen.
what do the conditions known as acidosis and alkalosis refer to?
the disruption of the body's pH balance
How do sodium and potassium travel into and out of cells?
There are transport proteins within the cell membrane that pick up and release the minerals across the membrane
How many grams of nitrogen are contained in a 2500-kcalorie diet that provides 15% of the energy as protein?
When nitrogen taken into the body exceeds nitrogen losses, we say the person is in what?
positive nitrogen balance.
What is the amino acid pool?
A mix of essential and nonessential amino acids derived from protein breakdown and dietary protein intake
What describes the state of nitrogen balance for a normal, healthy 35-year-old person who weighs 60 kg and consumes a diet that provides 75 g of protein and adequate energy?
What is the nitrogen balance of a person who consumed a 3500-kcalorie diet containing 10% protein and excreted a total of 12 grams of nitrogen?
what would describe the state of nitrogen balance of a person who ingested 16 g of food nitrogen and lost 19 g of nitrogen?
What is the usual state of nitrogen balance for healthy infants, children, and pregnant women?
What amino acid is used to synthesize the neurotransmitter serotonin and the vitamin niacin?
What is the fate of excess dietary protein?
After absorption, the extra amino acids will be rapidly degraded
Protein sparing in the body is best achieved when a person ingests ______.
adequate levels of carbs and fat
What is the process whereby an amino group is combined with a keto acid to form an amino acid?
a man who has a high blood ammonia concentration, most likely has a poorly functioning _________.
A reference protein equals or exceeds the essential amino acid requirements of what population groups?
preschool aged children, adolescents, and the elderly.
Which of the following food proteins has the best assortment of essential amino acids for the human body?
In the study of protein nutrition, what term describes the amount of amino acids absorbed from a given amount of protein consumed?
What is a "limiting" amino acid in a protein?
An essential amino acid present in insufficient quantity for body protein synthesis to take place
If the diet is lacking an essential amino acid, what will be the course of action?
Protein synthesis will be limited
what is characteristic of protein nutrition in vegetarians?
Most vegetarians eating a variety of foods need not balance essential amino acid intake at each meal
What is complementary protein nutrition?
A strategy that combines plant proteins in the same day to improve the balance of essential amino acids
In general, the protein quality in grains would be most improved by the addition of a plant protein rich in what?
In general, the protein quality of legumes would be most improved by the addition of a plant protein rich in what?
Relative to animal proteins, what amino acid is present in lesser amounts in proteins of legumes?
what are some are characteristics of protein-energy malnutrition?
it is found in hospitalized adults, it is found in elderly living alone, and it is common in people with anorexia nervosa.
what would you expect to see in a person with kwashiorkor?
Edema, Dysentery, and Increased infection rate
what is associated with the presence of tissue edema in kwashiorkor?
Low concentration of blood protein
what are some characteristics of marasmus?
Results in a low resistance to disease, Occurs most commonly in children aged 6 to 18 months, and Results in little or no fat under the skin to insulate against cold.
what is a feature of malnutrition?
Dysentery is common and leads to diarrhea and nutrient depletion.
how does the rapid onset of protein-energy malnutrition occurs in kwashiorkor?
It is typically seen in patients who are 1-3 years old due to the sudden change in diet arising from their being weaned from breast milk after the birth of a sibling
what is a condition is associated with edema?
Diminished concentration of blood proteins and hormones, which causes fluid to leak from the blood vessels
In kwashiorkor, what is the loss of hair color is indirectly related to?
inadequate intake of tyrosine
In kwashiorkor, what mineral is often present in an unbound form that promotes bacterial growth?
What is the most likely explanation for the fatty liver that develops from protein deficiency?
Inability of the liver to synthesize lipoproteins for fat export
what is a feature of kwashiorkor?
It is typically precipitated in the undernourished child who has an infection`
Excessive amounts of homocysteine in the blood are thought to increase the risk for ______.
Supplements of what amino acid is reported to lower blood pressure and reduce homocysteine levels?
what are known to raise the levels of homocysteine?
alcohol intake, cigarette smoking and coffee consumption.
what is a description of a relationship between protein/amino acids and heart disease?
Elevated blood homocysteine levels are associated with smoking cigarettes and drinking alcohol
what is a description of an association between protein intake and kidney function?
restricting protein intake may slow the progression of kidney disease
In relation to the range of protein intake as a percentage of energy intake, what would be the highest safe level of protein intake for a 60-kg adult ingesting 2500 kcalories?
what is a description of a relationship between protein intake and calcium metabolism?
Calcium excretion rises with increasing intake of animal-derived proteins
What would be the primary principle of wise diet planning as related to protein nutrition?
If protein needs are expressed per kilogram of body weight, which of the following describes the requirements of infants?
Greater than adults
Your friend Jill has just joined her community college soccer team. How much protein should she consume each day?
what is an assumption made in the formulation of the RDA for protein?
Dietary carbohydrate and fat intakes are adequate
what are some assumptions made by the committee in setting the RDA for protein?
adequate kcalories will be consumed, protein eaten will be of mixed quality, and other nutrients in the diet will be adequate.
what is a feature of protein nutrition?
The protein RDA assumes that dietary protein is from a mix of low- and high-quality sources
What is the percentage of total energy derived from protein in a diet containing 50 grams of protein and 2000 kcalories?
If a person consumes 65 grams of protein and a total of 2700 kcalories per day, approximately what percentage of energy would be derived from protein?
Jim, a college baseball player, tells you that he has started to take glutamine supplements. How would you advise him?
Since single amino acids do not occur naturally in foods, they offer no benefit to the body and may even be harmful
what is a feature of the branched-chain amino acids?
they may be helpful in treatment of advanced liver failure
What amino acid has been linked to the development of the rare blood disorder eosinophilia myalgia in people who took it as a supplement?
What amino acid supplement has been advertised in the popular media for treating herpes infections?
what is the study of how environmental factors influence the expression of genes without altering the DNA is known as?
what are some characteristics of phenylketonuria?
it is a single-gene disorder, it leads to a dietary requirement for tyrosine, and it results in mental retardation unless treatment is started in infancy.