Proteins Flashcards
Proteins are built from simpler organic compounds called
amino acids.
The element that is contained in proteins but not in carbohydrates or lipids is
nitrogen.
is present in proteins but not in carbohydrates or lipids. Amino acids, the building blocks of protein, are named for their chemical structure; amino refers to compounds containing nitrogen.
Two types of protein in the body are _____ protein and _____ protein.
tissue, plasma
Two types of protein in the body are tissue and plasma protein. Amino acids are classified as indispensable, dispensable, or conditionally indispensable in the diet according to whether the body can make them.
The number of amino acids that are indispensable for human beings is
9.
Nine amino acids are classified as indispensable amino acids because the body cannot manufacture them in sufficient quantity or at all.
In the diet, the greatest proportion of indispensable amino acids are provided by
animal products.
Indispensable amino acids are provided mostly by animal products that contain protein.
A protein that contains all indispensable amino acids in the correct proportion and ratio is called
complete.
A complete amino acid is one that is dispensable, meaning that the body can synthesize it from other amino acids.
The number of kilocalories from protein in a sandwich that contains 24 g protein is _____ kcal.
96
Each gram of protein has 4 kcal, so 24 g 4 kcal = 96 kcal.
An animal protein that has little value as a dietary protein source when eaten alone is
gelatin.
is a protein food of animal origin, but it lacks three essential amino acids and has only small amounts of leucine.
Proteins from plant sources such as grains, nuts, and legumes that are classified as incomplete include
grains, peanuts, and corn.
Grains, peanuts, and corn are considered incomplete proteins because the food is deficient in one or more of the nine indispensable amino acids.
To form a specific tissue protein, the order of amino acids must be
specific.
Once proteins are eaten and broken down into amino acids in the digestive process, they are reassembled in the body into a specific order to form a variety of different proteins, such as collagen, myosin, and hemoglobin.
The number of common amino acids is
20.
There are 20 common amino acids, all of which are important to human life and health.
An example of a protein-free body substance is
glycogen.
Glycogen is the storage form of carbohydrates and does not contain protein.
The primary function of protein in the diet is to supply
material for growth and maintenance.
The primary function of protein is to supply material in the body for growth, maintenance, and repair.
Protein plays an important role in the body
in defense against disease and infection.
Protein assists in the body’s defense against disease and infection by helping build special white blood cells called lymphocytes.
After a piece of grilled chicken is digested by the mouth and stomach, it eventually reaches the small intestine, where which of the following enzymes are secreted by the pancreas?
Chymotrypsin, trypsin, and carboxypeptidase
are three enzymes produced by the pancreas to continue breaking down proteins into simper and simpler substances.
Proteins are absorbed as
amino acids and peptides.
Proteins are broken down to amino acids and peptides, whereas polypeptides require enzymatic breakdown.
Pepsinogen secreted by the gastric cells is converted into pepsin by
hydrochloric acid.
Protein catabolism is increased in conditions such as
illness.
Protein catabolism, or the breakdown of protein, is increased during illness or disease and increases the body’s need for protein and kilocalories to rebuild tissue and meet the demands of an increased metabolic rate.
The phase of metabolism that makes growth and repair possible is
anabolism.
Anabolism is the metabolic process that makes growth and repair possible in the body. It is especially necessary after an illness or disease process. Anabolism also is found during periods of rapid fetal growth during pregnancy, the first year of life, lactation during breastfeeding, and adolescent growth and development into adulthood.
A gastric enzyme that coagulates milk and is present in infants but not in adults is
rennin.
Rennin is the gastric enzyme found in the gastric juice of human infants and some young animals such as calves. Rennin is important to the infant in the digestion of milk.
A protein-digesting enzyme found in the stomach rather than in pancreatic secretions is
pepsin.
is the main gastric enzyme specific to proteins.
The enzyme trypsin is activated by the enzyme
enterokinase.
Trypsin is activated by the enzyme enterokinase. Enterokinase is secreted from the intestinal cells on contact with food entering the duodenum.
The enzymes aminopeptidase and dipeptidase are secreted by the
small intestine.
Aminopeptidase and dipeptidase are enzymes secreted by glands in the wall of the small intestine.
Complementary proteins
provide higher quality protein when eaten together.
Complementary proteins are used to supply all nine indispensable amino acids for the diet. Because plant proteins are incomplete, a mixture can provide adequate amounts of amino acids. A normal eating pattern throughout the day along with the body’s reserve supply of protein ensures a complementary balance of high-quality protein. Those who follow a vegetarian eating pattern must combine proteins to meet needs.
In the mouth, protein is
broken up mechanically by chewing.
Of the following, the food with the highest quality protein is
egg.
Eggs are a high-quality protein food and carry a chemical score of 100. Other foods are compared to it according to their amino acid ratios.
Which of the following conditions might result in the greatest catabolism?
Multiple trauma with extensive organ damage
Protein catabolism, or the breakdown of protein, is increased during illness or disease and increases the body’s need for protein and kilocalories to rebuild tissue and meet the demands of an increased metabolic rate. In this case, multiple trauma with extensive organ damage requires a greater catabolic rate compared with the other choices and would create the greatest increase in metabolic rate and need for tissue repair.
DIF: Hard REF: 48 MSC: Application
If the excretion of nitrogen exceeds the nitrogen intake, the condition is called
negative nitrogen balance.
If the body takes in less nitrogen than it excretes, a negative balance occurs. This means that the body has an inadequate protein intake and is losing nitrogen by breaking down more tissue than it is building up.
The grams of protein required daily for an individual who weighs 170 lb ideal body weight would be _____ g.
55.3
The Recommended Daily Allowance for both men and women is set at 0.8 g of high-quality protein per kilogram of desirable body weight per day. In this case, 170 lb/2.2 lb/kg = 77 kg. 77 kg 0.8 g/kg = 61.6 g/day of protein.
In planning a vegetarian meal, an appropriate combination of complementary proteins would be
cornmeal tamales and beans.
In planning and making complementary food combinations to balance the needed amino acids, families of foods (e.g., grains, legumes, and dairy) are mixed. Grains usually are low in threonine and high in methionine, whereas legumes are the opposite. Therefore grains and legumes help balance each other in the amount of indispensable amino acids required by the body. Acceptable combinations include (1) grains and peas, beans, or lentils; (2) legumes and seeds; and (3) grains and dairy. In the choices given, cornmeal tamales and beans would be the most appropriate food choice.
An example of a low-protein food is
fresh fruit salad.
Fresh fruit salad is composed mostly of carbohydrates and no protein.
