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Questions and Answers
What is the average protein intake in the United States per day?
What is the average protein intake in the United States per day?
80 grams
What is the protein RDA for adults?
What is the protein RDA for adults?
0.8 grams per kilogram of healthy body weight
What percentage of recommended protein intake should come from seafood?
What percentage of recommended protein intake should come from seafood?
Fruits are a significant source of protein.
Fruits are a significant source of protein.
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How many grams of protein does a serving of milk or yogurt provide?
How many grams of protein does a serving of milk or yogurt provide?
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What is the recommended total protein intake from meat, poultry, and eggs over a week?
What is the recommended total protein intake from meat, poultry, and eggs over a week?
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What is the primary use of protein powders among athletes?
What is the primary use of protein powders among athletes?
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The disease kwashiorkor is associated with ____________ protein deficiency.
The disease kwashiorkor is associated with ____________ protein deficiency.
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Marasmus is a condition associated with protein deficiency only.
Marasmus is a condition associated with protein deficiency only.
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What effect do protein and amino acid supplements typically offer?
What effect do protein and amino acid supplements typically offer?
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What are proteins composed of?
What are proteins composed of?
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Which of the following amino acids are considered essential?
Which of the following amino acids are considered essential?
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What is a conditionally essential amino acid?
What is a conditionally essential amino acid?
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Proteins are linked together in a chain by ____ bonds.
Proteins are linked together in a chain by ____ bonds.
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What determines the primary structure of a protein?
What determines the primary structure of a protein?
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Denaturation is a reversible process.
Denaturation is a reversible process.
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Which organ primarily breaks down proteins during digestion?
Which organ primarily breaks down proteins during digestion?
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What is protein digestibility influenced by?
What is protein digestibility influenced by?
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What is a limiting amino acid?
What is a limiting amino acid?
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What happens to the body when there is a protein deficiency?
What happens to the body when there is a protein deficiency?
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Consuming high protein diets leads to an increase in kidney disease.
Consuming high protein diets leads to an increase in kidney disease.
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What are complementary proteins?
What are complementary proteins?
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What is the average protein intake in the United States per day?
What is the average protein intake in the United States per day?
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What is the recommended protein intake (RDA) for adults in grams per kilogram of body weight?
What is the recommended protein intake (RDA) for adults in grams per kilogram of body weight?
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What percentage of protein intake in a week is recommended to come from meat, poultry, and eggs?
What percentage of protein intake in a week is recommended to come from meat, poultry, and eggs?
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How much protein is provided by a serving (a cup) of milk or yogurt?
How much protein is provided by a serving (a cup) of milk or yogurt?
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Fruits contain significant amounts of protein.
Fruits contain significant amounts of protein.
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According to food labels, when is the '% Daily Value' for protein required?
According to food labels, when is the '% Daily Value' for protein required?
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What health problem is associated with protein deficiency known as 'Kwashiorkor'?
What health problem is associated with protein deficiency known as 'Kwashiorkor'?
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What is a symptom of Marasmus?
What is a symptom of Marasmus?
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Which of the following protein sources delivers about 7 grams of protein per ounce?
Which of the following protein sources delivers about 7 grams of protein per ounce?
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What is one reason athletes take protein powders?
What is one reason athletes take protein powders?
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What are proteins composed of?
What are proteins composed of?
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What are nonessential amino acids?
What are nonessential amino acids?
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What are essential amino acids?
What are essential amino acids?
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Amino acid chains are connected by peptide bonds.
Amino acid chains are connected by peptide bonds.
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What determines the primary structure of a protein?
What determines the primary structure of a protein?
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What happens to proteins when they undergo denaturation?
What happens to proteins when they undergo denaturation?
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What is the role of hydrochloric acid in the stomach regarding protein digestion?
What is the role of hydrochloric acid in the stomach regarding protein digestion?
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What is the primary function of dietary proteins?
What is the primary function of dietary proteins?
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What is a high-quality protein?
What is a high-quality protein?
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Combining plant proteins at every meal is critical for protein nutrition.
Combining plant proteins at every meal is critical for protein nutrition.
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What can excessive protein losses during critical illness lead to?
What can excessive protein losses during critical illness lead to?
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What factor is associated with a reduced risk of some cancers?
What factor is associated with a reduced risk of some cancers?
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What does a high-protein diet potentially contribute to?
What does a high-protein diet potentially contribute to?
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What is the limiting amino acid?
What is the limiting amino acid?
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What is the primary characteristic of a high-quality protein?
What is the primary characteristic of a high-quality protein?
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Which of the following foods is considered a low-quality protein?
Which of the following foods is considered a low-quality protein?
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How can vegetarians enhance the protein quality in their diets?
How can vegetarians enhance the protein quality in their diets?
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Which amino acid is considered limiting if it is found in the shortest supply for protein synthesis?
Which amino acid is considered limiting if it is found in the shortest supply for protein synthesis?
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What term is used to describe proteins derived from animals that generally provide high-quality protein?
What term is used to describe proteins derived from animals that generally provide high-quality protein?
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What primarily determines the secondary structure of proteins?
What primarily determines the secondary structure of proteins?
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Which term describes the twisting and folding of long polypeptide chains?
Which term describes the twisting and folding of long polypeptide chains?
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What happens to protein structures during denaturation?
What happens to protein structures during denaturation?
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What characterizes the quaternary structure of proteins?
What characterizes the quaternary structure of proteins?
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How do amino acid side groups influence protein structure?
How do amino acid side groups influence protein structure?
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Which of these is a consequence of protein denaturation?
Which of these is a consequence of protein denaturation?
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What role do weak electrical attractions play in polypeptide chains?
What role do weak electrical attractions play in polypeptide chains?
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Which example illustrates irreversible denaturation?
Which example illustrates irreversible denaturation?
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Which of the following accurately describes dietary proteins?
Which of the following accurately describes dietary proteins?
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What occurs to proteins under heat or acids?
What occurs to proteins under heat or acids?
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What is a consequence of protein malnutrition related to fluid balance?
What is a consequence of protein malnutrition related to fluid balance?
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What does the digestibility of plant proteins typically range from?
What does the digestibility of plant proteins typically range from?
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What is the primary structural function of proteins in the human body?
What is the primary structural function of proteins in the human body?
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Which factor does NOT influence protein quality?
Which factor does NOT influence protein quality?
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Which condition can arise from inadequate dietary protein intake?
Which condition can arise from inadequate dietary protein intake?
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What role do proteins play in the regulation of fluid balance?
What role do proteins play in the regulation of fluid balance?
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Which scenario would NOT likely cause excessive protein losses?
Which scenario would NOT likely cause excessive protein losses?
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Which type of protein has the highest digestibility?
Which type of protein has the highest digestibility?
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What causes cells to fail to function adequately during protein deficiency?
What causes cells to fail to function adequately during protein deficiency?
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What is the primary role of dietary proteins in the body?
What is the primary role of dietary proteins in the body?
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What role does hydrochloric acid play in protein digestion in the stomach?
What role does hydrochloric acid play in protein digestion in the stomach?
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In the small intestine, what further breaks down polypeptides?
In the small intestine, what further breaks down polypeptides?
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What is the final product of protein digestion capable of being absorbed by intestinal cells?
What is the final product of protein digestion capable of being absorbed by intestinal cells?
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What happens to amino acids after they enter the intestinal cells?
What happens to amino acids after they enter the intestinal cells?
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How does eating predigested proteins affect the digestive system?
How does eating predigested proteins affect the digestive system?
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What is a consequence of consuming whole proteins rather than amino acid supplements?
What is a consequence of consuming whole proteins rather than amino acid supplements?
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Which compounds primarily transport amino acids into intestinal cells?
Which compounds primarily transport amino acids into intestinal cells?
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What action occurs to dipeptides and tripeptides during protein digestion?
What action occurs to dipeptides and tripeptides during protein digestion?
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What is the primary function of pepsin during protein digestion?
What is the primary function of pepsin during protein digestion?
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Which type of enzyme primarily acts on peptides at the membrane surfaces of intestinal cells?
Which type of enzyme primarily acts on peptides at the membrane surfaces of intestinal cells?
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What is the primary function of essential amino acids in the body?
What is the primary function of essential amino acids in the body?
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Which amino acid becomes conditionally essential under certain circumstances?
Which amino acid becomes conditionally essential under certain circumstances?
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What type of reaction is responsible for forming peptide bonds between amino acids?
What type of reaction is responsible for forming peptide bonds between amino acids?
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How many essential amino acids must be obtained from the diet?
How many essential amino acids must be obtained from the diet?
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Which of the following describes nonessential amino acids?
Which of the following describes nonessential amino acids?
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What is true about the primary structure of a protein?
What is true about the primary structure of a protein?
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What do condensation reactions achieve in the context of protein synthesis?
What do condensation reactions achieve in the context of protein synthesis?
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Which group of amino acids is typically classified as dispensable?
Which group of amino acids is typically classified as dispensable?
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What is the primary reason the body requires dietary protein?
What is the primary reason the body requires dietary protein?
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What percent of a typical 2000-kilocalorie diet should consist of protein according to dietary guidelines?
What percent of a typical 2000-kilocalorie diet should consist of protein according to dietary guidelines?
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For adults, what is the recommended daily allowance (RDA) of protein in grams per kilogram of healthy body weight?
For adults, what is the recommended daily allowance (RDA) of protein in grams per kilogram of healthy body weight?
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What percentage of protein foods should ideally come from nuts, seeds, and legumes over the course of a week?
What percentage of protein foods should ideally come from nuts, seeds, and legumes over the course of a week?
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What is the reason that older adults may benefit from protein intake slightly higher than current recommendations?
What is the reason that older adults may benefit from protein intake slightly higher than current recommendations?
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What classification has the World Health Organization assigned to processed meat regarding cancer risk?
What classification has the World Health Organization assigned to processed meat regarding cancer risk?
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How does high protein intake potentially affect bone health?
How does high protein intake potentially affect bone health?
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What role does dietary protein play in weight-loss diets that are high in protein and low in carbohydrates?
What role does dietary protein play in weight-loss diets that are high in protein and low in carbohydrates?
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What is the impact of a high protein diet on kidney function in individuals with healthy kidneys?
What is the impact of a high protein diet on kidney function in individuals with healthy kidneys?
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Which protein-rich food has been associated with a lower risk of breast cancer?
Which protein-rich food has been associated with a lower risk of breast cancer?
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What is the primary reason the DRI Committee did not establish a UL for protein?
What is the primary reason the DRI Committee did not establish a UL for protein?
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What can excessive protein intake lead to regarding body fat and lean body mass?
What can excessive protein intake lead to regarding body fat and lean body mass?
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Which of the following statements is true about the relationship between protein intake and kidney disease?
Which of the following statements is true about the relationship between protein intake and kidney disease?
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Which of the following foods is generally not associated with an increase in cancer risk?
Which of the following foods is generally not associated with an increase in cancer risk?
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How does protein intake relate to feelings of hunger and fullness?
How does protein intake relate to feelings of hunger and fullness?
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What is the role of hydrochloric acid in the stomach during protein digestion?
What is the role of hydrochloric acid in the stomach during protein digestion?
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Which enzymes are primarily responsible for further hydrolyzing polypeptides in the small intestine?
Which enzymes are primarily responsible for further hydrolyzing polypeptides in the small intestine?
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What happens to amino acids that are not utilized by the intestinal cells?
What happens to amino acids that are not utilized by the intestinal cells?
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How does predigested protein differ from whole proteins in terms of digestion?
How does predigested protein differ from whole proteins in terms of digestion?
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What does the enzyme pepsin primarily do during protein digestion?
What does the enzyme pepsin primarily do during protein digestion?
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Which statement is true about the absorption of proteins?
Which statement is true about the absorption of proteins?
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What is the main reason why the digestive system handles whole proteins better than predigested proteins?
What is the main reason why the digestive system handles whole proteins better than predigested proteins?
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During digestion, what ultimately happens to short polypeptides and dipeptides?
During digestion, what ultimately happens to short polypeptides and dipeptides?
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What is a primary function of proteins in the body?
What is a primary function of proteins in the body?
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What can result from the leakage of plasma proteins during critical illness?
What can result from the leakage of plasma proteins during critical illness?
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How does the digestibility of animal proteins generally compare to plant proteins?
How does the digestibility of animal proteins generally compare to plant proteins?
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Which factor is NOT associated with protein quality?
Which factor is NOT associated with protein quality?
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What might inadequate dietary intake of protein lead to?
What might inadequate dietary intake of protein lead to?
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What is a consequence of excessive protein losses during illness?
What is a consequence of excessive protein losses during illness?
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What defines a high-quality protein?
What defines a high-quality protein?
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What is the primary reason vegetarians combine different plant-protein foods?
What is the primary reason vegetarians combine different plant-protein foods?
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Which of the following describes a characteristic of high-quality proteins?
Which of the following describes a characteristic of high-quality proteins?
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Which food source provides high-quality proteins despite being an exception?
Which food source provides high-quality proteins despite being an exception?
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What could result from both inadequate protein synthesis and protein malnutrition?
What could result from both inadequate protein synthesis and protein malnutrition?
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What happens to proteins during digestion?
What happens to proteins during digestion?
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What is a limiting amino acid?
What is a limiting amino acid?
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What is a role of proteins related to fluid balance in the body?
What is a role of proteins related to fluid balance in the body?
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Which of the following is true about plant proteins compared to animal proteins?
Which of the following is true about plant proteins compared to animal proteins?
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What must be supplied by dietary protein to prevent the breakdown of the body's own proteins?
What must be supplied by dietary protein to prevent the breakdown of the body's own proteins?
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Why are some plant proteins considered lower quality than animal proteins?
Why are some plant proteins considered lower quality than animal proteins?
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Which amino acid is commonly noted to be limiting in certain plant proteins?
Which amino acid is commonly noted to be limiting in certain plant proteins?
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How is the quality of food protein assessed for preschool-age children?
How is the quality of food protein assessed for preschool-age children?
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What is the total amount of protein provided by 3 cups of milk?
What is the total amount of protein provided by 3 cups of milk?
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Why do athletes commonly consume protein powders after exercise?
Why do athletes commonly consume protein powders after exercise?
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What is a common misconception about protein and amino acid supplements?
What is a common misconception about protein and amino acid supplements?
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What does the % Daily Value for protein on food labels reflect?
What does the % Daily Value for protein on food labels reflect?
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What is the primary reason for the variation in protein requirements among individuals?
What is the primary reason for the variation in protein requirements among individuals?
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What type of amino acids must be obtained from the diet due to the body's inability to synthesize them?
What type of amino acids must be obtained from the diet due to the body's inability to synthesize them?
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Which amino acid becomes conditionally essential under specific circumstances like insufficient dietary intake or metabolic issues?
Which amino acid becomes conditionally essential under specific circumstances like insufficient dietary intake or metabolic issues?
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What is the primary structure of a protein determined by?
What is the primary structure of a protein determined by?
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Which process involves the linking of two amino acids to form a dipeptide?
Which process involves the linking of two amino acids to form a dipeptide?
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What term describes amino acids that the body can synthesize and do not need to be obtained from the diet?
What term describes amino acids that the body can synthesize and do not need to be obtained from the diet?
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What is formed when the acid end of one amino acid links with the amino end of another?
What is formed when the acid end of one amino acid links with the amino end of another?
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Which of the following is a characteristic of conditionally essential amino acids?
Which of the following is a characteristic of conditionally essential amino acids?
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How many essential amino acids must be obtained through diet?
How many essential amino acids must be obtained through diet?
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What is the main function of hydrochloric acid in the stomach during protein digestion?
What is the main function of hydrochloric acid in the stomach during protein digestion?
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What is primarily absorbed into the intestinal cells after protein digestion?
What is primarily absorbed into the intestinal cells after protein digestion?
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What process occurs when polypeptides enter the small intestine?
What process occurs when polypeptides enter the small intestine?
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Which statement about predigested proteins is accurate?
Which statement about predigested proteins is accurate?
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What role do peptidase enzymes play in protein absorption?
What role do peptidase enzymes play in protein absorption?
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What happens to amino acids that are not used by intestinal cells?
What happens to amino acids that are not used by intestinal cells?
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During the absorption of proteins, what facilitates the transport of amino acids into intestinal cells?
During the absorption of proteins, what facilitates the transport of amino acids into intestinal cells?
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What is the initial action taken by digestive enzymes on dietary proteins in the stomach?
What is the initial action taken by digestive enzymes on dietary proteins in the stomach?
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How are proteins primarily broken down during digestion?
How are proteins primarily broken down during digestion?
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Which factor primarily determines the efficiency of protein digestion?
Which factor primarily determines the efficiency of protein digestion?
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What is the primary consequence of protein deficiency?
What is the primary consequence of protein deficiency?
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Which dietary approach may improve blood pressure and decrease heart disease mortality?
Which dietary approach may improve blood pressure and decrease heart disease mortality?
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What is the common belief about combining plant proteins?
What is the common belief about combining plant proteins?
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Which amino acid is associated with protecting against heart disease?
Which amino acid is associated with protecting against heart disease?
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How can vegetarians obtain all necessary amino acids throughout the day?
How can vegetarians obtain all necessary amino acids throughout the day?
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What is often more prevalent than protein deficiency in developed countries?
What is often more prevalent than protein deficiency in developed countries?
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What does inadequate protein lead to regarding nutrient absorption?
What does inadequate protein lead to regarding nutrient absorption?
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Which B vitamin is mentioned as possibly lowering homocysteine levels?
Which B vitamin is mentioned as possibly lowering homocysteine levels?
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What happens to body proteins when there is a consistent protein deficiency?
What happens to body proteins when there is a consistent protein deficiency?
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How is homocysteine related to heart disease?
How is homocysteine related to heart disease?
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What is the primary reason the body requires dietary protein?
What is the primary reason the body requires dietary protein?
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Which of the following is the recommended amount of protein intake for adults based on body weight?
Which of the following is the recommended amount of protein intake for adults based on body weight?
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What percentage of total food energy should be provided by protein in a balanced diet?
What percentage of total food energy should be provided by protein in a balanced diet?
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What is the recommended daily protein intake, in grams, for someone consuming a 2000-calorie diet?
What is the recommended daily protein intake, in grams, for someone consuming a 2000-calorie diet?
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Which food group is specifically noted as another significant source of protein aside from meat products?
Which food group is specifically noted as another significant source of protein aside from meat products?
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How much protein, in grams, is typically found in an ounce of most protein foods?
How much protein, in grams, is typically found in an ounce of most protein foods?
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What is the suggested intake of seafood in a week based on recommended protein food distribution?
What is the suggested intake of seafood in a week based on recommended protein food distribution?
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What is one benefit of consuming slightly higher protein intake for older adults?
What is one benefit of consuming slightly higher protein intake for older adults?
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The body's need for nitrogen can be met primarily through which source?
The body's need for nitrogen can be met primarily through which source?
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What is the primary function of protein in the body?
What is the primary function of protein in the body?
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What is the approximate protein content of a serving of vegetables?
What is the approximate protein content of a serving of vegetables?
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How much protein do six ounces of grains provide?
How much protein do six ounces of grains provide?
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What is a primary reason athletes consume protein powders after exercising?
What is a primary reason athletes consume protein powders after exercising?
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When is the '% Daily Value' for protein mandatory on food labels?
When is the '% Daily Value' for protein mandatory on food labels?
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What is a misconception regarding protein and amino acid supplements?
What is a misconception regarding protein and amino acid supplements?
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Which type of amino acids must be obtained from the diet?
Which type of amino acids must be obtained from the diet?
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What is formed when two amino acids undergo a condensation reaction?
What is formed when two amino acids undergo a condensation reaction?
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Which amino acid can become conditionally essential under certain circumstances?
Which amino acid can become conditionally essential under certain circumstances?
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What characterizes nonessential amino acids?
What characterizes nonessential amino acids?
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How many essential amino acids are required by the human body?
How many essential amino acids are required by the human body?
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What connects the acid end of one amino acid to the amino end of another?
What connects the acid end of one amino acid to the amino end of another?
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Which of the following statements is true regarding conditionally essential amino acids?
Which of the following statements is true regarding conditionally essential amino acids?
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What determines the primary structure of a protein?
What determines the primary structure of a protein?
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What is the recommended percentage of total food energy that should be contributed by protein?
What is the recommended percentage of total food energy that should be contributed by protein?
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What is the main reason the body requires dietary protein?
What is the main reason the body requires dietary protein?
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How much protein is recommended daily for adults based on body weight?
How much protein is recommended daily for adults based on body weight?
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What is not a consequence of protein deficiency?
What is not a consequence of protein deficiency?
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How much of the protein foods per week should come from seafood according to dietary guidelines?
How much of the protein foods per week should come from seafood according to dietary guidelines?
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What is the average intake of protein per day in the United States?
What is the average intake of protein per day in the United States?
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Why is it generally unnecessary for vegetarians to combine proteins at every meal?
Why is it generally unnecessary for vegetarians to combine proteins at every meal?
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What dietary change may improve heart disease outcomes?
What dietary change may improve heart disease outcomes?
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What percentage of protein should ideally come from nuts, seeds, and legumes in a weekly diet?
What percentage of protein should ideally come from nuts, seeds, and legumes in a weekly diet?
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What is the role of homocysteine in relation to heart disease?
What is the role of homocysteine in relation to heart disease?
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What is the suggested protein intake per meal for optimal muscle health?
What is the suggested protein intake per meal for optimal muscle health?
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What role does nitrogen play in the body regarding dietary protein?
What role does nitrogen play in the body regarding dietary protein?
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What indicates a high protein intake may be problematic?
What indicates a high protein intake may be problematic?
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What is often included in protein-rich diets that can affect blood pressure levels?
What is often included in protein-rich diets that can affect blood pressure levels?
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What is the function of protein in a diet compared to fats and carbohydrates?
What is the function of protein in a diet compared to fats and carbohydrates?
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How many grams of protein does an ounce of most protein foods generally deliver?
How many grams of protein does an ounce of most protein foods generally deliver?
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What dietary factor is associated with reduced health risks, including heart disease?
What dietary factor is associated with reduced health risks, including heart disease?
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How can a varied diet help vegetarians regarding protein intake?
How can a varied diet help vegetarians regarding protein intake?
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Which vitamin is not suggested to lower heart attack risks despite affecting homocysteine levels?
Which vitamin is not suggested to lower heart attack risks despite affecting homocysteine levels?
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What dietary approach can contribute to improved blood lipid levels?
What dietary approach can contribute to improved blood lipid levels?
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What must dietary protein provide to prevent protein breakdown in the body?
What must dietary protein provide to prevent protein breakdown in the body?
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What is defined as a limiting amino acid?
What is defined as a limiting amino acid?
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Which foods are typically sources of high-quality protein?
Which foods are typically sources of high-quality protein?
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Which plant protein is considered to be of high quality?
Which plant protein is considered to be of high quality?
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What strategy do vegetarians often use to improve protein quality in their diets?
What strategy do vegetarians often use to improve protein quality in their diets?
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What characterizes a high-quality protein?
What characterizes a high-quality protein?
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Study Notes
Protein and Daily Value
- Researchers must consider both the quality and quantity of protein when determining the Daily Value percentage.
- 6 ounces of grains provide 18 grams of protein.
- 2.5 cups of vegetables contain 10 grams of protein.
- 3 cups of milk supply 24 grams of protein.
- 5.5 ounces of protein foods provide 38 grams of protein.
- These amounts total 90 grams of protein, which is higher than the Recommended Dietary Allowance (RDA) for most people.
- The key principle to emphasize is moderation in protein intake.
Protein Supplements
- Protein powders are taken by athletes to build muscle, dieters to spare body protein during weight loss, and women to strengthen fingernails.
- Individuals take individual amino acids to treat herpes, improve sleep, lose weight, and alleviate pain and depression.
- These supplements do not offer miracles.
Protein Powders
- Many athletes consume protein powders shortly after exercising, particularly during resistance training, to stimulate protein synthesis and muscle strength.
- The impact of this increased protein synthesis on muscle building and performance is not definitively proven.
- Protein supplements are relatively safe and affordable, contributing to their popularity.
Amino Acid Supplements
- Some single amino acid supplements have gained wide use based on recommendations.
- Lysine: Lysine is recommended for preventing or alleviating herpes infections, such as cold sores. It is typically taken in divided doses with meals, up to 3 grams per day.
- Tryptophan: To counter depression or insomnia, tryptophan is recommended, with a maximum daily intake of 5 grams.
Protein Deficiency
- Kwashiorkor: This condition signifies insufficient protein intake while energy needs are met. Symptoms typically emerge between 12 months and 2 years of age and include edema (swelling) in the legs and abdomen (potbelly), alterations in hair and skin color, liver enlargement, and a compromised immune system.
- Marasmus: Marasmus involves deficiencies in both protein and energy. Symptoms manifest after 6 months of age and involve muscle wasting without edema.
Proteins
- Are composed of carbon, hydrogen, oxygen and nitrogen, some also contain sulfur
- Are needed for bodily functions, including maintaining cells, enzymes and hormones
- Nonessential amino acids are those the body can produce
- Essential amino acids are those the body cannot produce and must be consumed through diet
Amino Acids
- There are nine essential amino acids that the human body either cannot make at all or cannot make in sufficient quantity to meet its needs.
- Conditionally Essential Amino Acids: are normally nonessential, but become essential in special circumstances
- Example: tyrosine becomes a conditionally essential amino acid if the diet fails to supply enough phenylalanine, or if the body cannot make the conversion.
Protein Structure
- Primary Structure: determined by the sequence of amino acids, unique for each protein
- Secondary Structure: determined by weak electrical attraction within polypeptide chains, gives proteins strength and rigidity
- Tertiary Structure: long polypeptide chains twist and fold into variety of complex, tangled shapes, due to interactions of amino acid groups with surrounding fluids and other amino acids
- Quaternary Structure: involves the interactions between two or more polypeptides
- Denaturation: disrupts protein structure and function, resulting in loss of shape and functionality, caused by factors like heat and acid
Protein Digestion and Absorption
- Digestion begins in the stomach with hydrochloric acid denaturing proteins and activating pepsin
- Pepsin breaks down proteins into smaller polypeptides and amino acids
- In the small intestine, pancreatic and intestinal proteases further hydrolyze polypeptides into amino acids, tripeptides and dipeptides
- Peptidase enzymes on intestinal cell surfaces break down dipeptides and tripeptides into single amino acids
- Absorbed amino acids may be used for energy or protein synthesis
- Undigested amino acids are transported to the liver
Functions of Proteins
- Structural Materials: Proteins form the building blocks of muscles, blood and skin, it is a major structural component of all the body's cells
- Enzymes: Act as catalysts for biochemical reactions like digestion
- Hormones: Regulate bodily processes, examples include insulin and growth hormone
- Regulators Of Fluid Balance: Maintain fluid balance, prevent edema by keeping proteins within cells and blood plasma
Protein Quality
- High-quality proteins contain all essential amino acids in sufficient amounts, and may or may not contain all nonessential amino acids
- Low-quality proteins lack some essential amino acids
- Two factors affect protein quality:
- Digestibility: affected by the protein source and foods eaten with it, animal proteins are generally more digestible than plant proteins
- Amino Acid Composition: the types and amounts of amino acids present
- Limiting Amino Acid: the essential amino acid found in the shortest supply relative to the amounts needed for protein synthesis in the body, can impact protein quality
- Complementary Proteins: Combining plant-protein foods with different amino acid patterns, can provide all the essential amino acids
- Reference Protein: A standard used to determine the quality of a food protein based on its amino acid composition with the essential amino acid requirements of preschool-age children.
Recommended Protein Intake
- Protein Deficiency: Occurs when the diet lacks essential amino acids, results in slowed growth, impaired brain and kidney functions, poor immunity and inadequate nutrient absorption
- Heart Disease: High protein intake from animal sources may contribute to heart disease, however, replacing animal with vegetable protein may improve blood pressure and blood lipids
- Cancer: While protein itself doesn't increase cancer risk, some protein-rich foods may do, processed meats are classified as carcinogenic while legumes, fish and milk may lower cancer risk
- Adult Bone Loss: High protein intake may increase calcium excretion, potentially impacting bone health, however, the impact may depend on sufficient calcium intake
- Weight Loss: High protein diets may help with weight loss by promoting satiety
- Kidney Disease: High protein intake can increase the work of the kidneys, it may accelerate kidney deterioration in people with chronic kidney disease
- Protein RDA: 0.8 gram per kilogram of healthy body weight per day for adults
-
Protein Food Groups:
- Seafood - 20% of weekly protein intake
- Meat, poultry, and eggs - 70% of weekly protein intake
- Nuts, seeds, and legumes - 10% of weekly protein intake
- Milk and Milk Products: A cup of milk or yogurt provides about 8 grams of protein
- Fruits, Vegetables, and Grains: Fruits do not contain protein. Vegetables and grains provide 2-3 grams of protein per serving
Protein Intake Guidelines
- The USDA Food Patterns encourage a variety of protein sources
- Choose lean meats and poultry
- Include plenty of plant-based protein sources, such as legumes, nuts and seeds
- Consider protein intake over a week to balance essential amino acid intake
Daily Value of Protein
- When the Daily Value percentage is declared, researchers must determine the quality of the protein.
- The Daily Value percentage for protein reflects both quantity and quality.
Protein Sources and Intake
- Six ounces of grains provide about 18 grams of protein.
- 2.5 cups of vegetables deliver about 10 grams of protein
- 3 cups of milk offer 24 grams of protein.
- 5.5 ounces of protein foods supply 38 grams of protein.
- The total protein from these sources is 90 grams.
- The recommended dietary allowance (RDA) for protein is lower than the 90 grams provided by these food sources.
- Most Americans get more than their recommended intake for protein.
Protein Supplements
- Protein powders are taken after exercises to build muscle.
- Diets take protein powders to spare their bodies' protein when losing weight.
- Women take protein powders to strengthen their fingernails.
- People take amino acid supplements for purposes such as curing herpes, improving sleep, losing weight, relieving pain and depression, and other health problems.
- However, these supplements do not provide miracle cures.
Protein Powders
- Many athletes take protein powders to build muscle particularly after strength training.
- Whether these powders actually build muscle and improve performance is unclear.
- However, they are relatively safe and inexpensive, so they remain popular.
Amino Acid Supplements
- Lysine:
- Lysine supplements, up to 3 grams taken with meals in divided doses, are used to prevent or relieve infections that cause herpes cold sores.
- Tryptophan:
- Tryptophan supplements, up to 5 grams per day, are used to relieve depression and insomnia.
Protein Deficiency
- Protein deficiency is a serious health condition.
- There are two main types of protein deficiency: kwashiorkor and marasmus.
Kwashiorkor
- Kwashiorkor is a disease caused by insufficient protein intake but not insufficient energy intake.
- It is characterized by edema (swelling) in the legs and abdomen (potbelly), changes in hair and skin color, liver enlargement, and a weakened immune system.
- Symptoms usually appear in children between 12 months and 2 years old.
Marasmus
- Marasmus is a disease caused by a deficiency in both protein and energy.
- It is characterized by muscle wasting (atrophy) without edema.
- Symptoms usually appear in infants after 6 months of age.
Protein: Amino Acids
- Proteins are composed of carbon, hydrogen, oxygen, and nitrogen, with some also containing sulfur.
- Amino acids are the building blocks of proteins, linked together in chains.
- Nonessential amino acids: The body can make these given nitrogen to help with the amino structure.
- Essential amino acids: The body cannot make these and must be obtained from the diet. Humans need nine essential amino acids.
- Conditionally Essential amino acids: Typically nonessential but must be consumed due to the body's inability to produce it in sufficient quantities.
- Peptide Bond: Connects the acid end of one amino acid to the amino end of another.
-
Primary Structure
- Determined by the order of amino acids.
- Each amino acid is a stepping stone in the polypeptide.
- Amino acid sequencing within proteins varies.
-
Secondary Structure
- Determined by weak electrical attractions between polypeptide chains.
- Positive hydrogen attracts negative oxygen.
- Provides strength and rigidity.
-
Tertiary Structure
- Long polypeptide chains twist and fold in complex shapes.
- Amino acid side groups determine attraction or repulsion to surrounding fluids and other amino acids.
- Hydrophilic amino acid side groups are attracted to water molecules.
- Hydrophobic amino acid side groups are repelled by water molecules.
-
Quaternary Structure
- Interactions between two or more polypeptides.
- Hemoglobin, which carries oxygen, has four polypeptide chains, each containing an iron atom.
-
Protein Denaturation
- The structure is disrupted by heat, acid, or other conditions.
- Tertiary, secondary, and quaternary structures are lost.
- Proteins lose their functionality.
- Examples: cooking an egg, curdling of milk, stiffening of egg whites.
-
Digestion and Absorption of Proteins
- Proteins in foods don't directly become body proteins.
- The body breaks down proteins into amino acids.
- Stomach: Hydrochloric acid denatures proteins, allowing enzymes to break down peptide bonds. Pepsinogen is activated to pepsin.
- Small Intestine: Pancreatic and intestinal proteases further break down proteins into smaller chains, tripeptides, dipeptides, and amino acids. Peptidase enzymes on the intestinal cell membranes split the tripeptides and dipeptides into individual amino acids.
-
Absorption of Proteins
- Amino acids and some dipeptides and tripeptides are transported across intestinal cell membranes into the bloodstream.
- Amino acids can be used for energy or synthesis within the intestinal cells.
- Unused amino acids are transported into surrounding fluid and then capillaries to the liver.
- Eating predgested proteins (amino acid supplements): Not better than whole proteins as the digestive system is meant to breakdown whole proteins.
-
Roles of Proteins
- Structural Materials: Proteins form the building blocks of muscles, blood, and skin. It is the main structural component of all cells.
- Enzymes: Digestive enzymes are proteins.
- Hormones: Hormones are proteins that regulate body processes.
- Regulators of Fluid Balance: Proteins help maintain the fluid balance of the body.
- Protein-related causes of edema: Excessive protein losses from inflammation, critical illnesses, inadequate protein synthesis from liver disease, and inadequate dietary intake of proteins.
-
Protein in Foods
- Protein Quality: Determines growth in children and overall health in adults.
- Factors Influencing Protein Quality: Protein's digestibility and amino acid composition.
- Digestibility: Ranges from 90-99% for animal proteins and 70-90% for plant proteins, except for soy and legumes, which are higher.
- Amino Acid Composition: The liver can make any nonessential amino acid, so protein is needed to supply essential amino acids.
- Reference Protein: Used to determine the quality of food protein by comparing its amino acid composition to essential amino acid requirements for young children.
- Limiting Amino Acid: The essential amino acid found in the shortest supply relative to the amount needed for protein synthesis.
- High-Quality Proteins: Contain all essential amino acids in the proportions that humans need. Animal proteins are typically high quality, except for gelatin.
- Low-Quality Proteins: Plant proteins have more diverse amino acid patterns and tend to be limiting in one or more essential amino acids, though some are high quality like soy proteins.
- Complementary Proteins: Combining plant-based proteins with different amino acid profiles to obtain all essential amino acids.
Protein Digestion
- Proteins are broken down into amino acids through digestion in the stomach and small intestine.
- Enzymes play a critical role in breaking down proteins into individual amino acids.
- Hydrochloric acid plays a key role in protein digestion by uncoiling protein strands and activating pepsin.
- Pepsin, an enzyme produced in the stomach, breaks down proteins into smaller polypeptides.
- In the small intestine: pancreatic enzymes further digest polypeptides into smaller chains, tripeptides, dipeptides, and amino acids.
- Peptidase enzymes digest tripeptides and dipeptides into single amino acids, with only a few peptides entering the blood intact.
Protein Absorption
- Amino acids are transported across the intestinal cell membrane into the bloodstream, where they travel to the liver.
- The liver can use absorbed amino acids for energy production or biosynthesis of necessary compounds.
- Consuming predigested proteins (amino acid supplements) is not recommended as the body handles whole proteins more efficiently.
Protein Roles
- Structural Materials: Proteins build and maintain muscles, blood, and skin, forming the foundation of all cells.
- Enzymes: Act as catalysts for various biochemical reactions throughout the body.
- Hormones: Regulate body processes.
- Fluid Balance: Proteins help maintain fluid balance by drawing water into the bloodstream, preventing edema (swelling).
- Transport: Proteins carry vital substances such as oxygen and nutrients through the bloodstream.
- Immune Function: Antibodies, a type of protein, play a critical role in the immune system.
- Energy: Proteins can be used as an energy source, but their primary role is structural.
Determining Protein Quality
- Two key factors influence protein quality:
- Digestibility: How efficiently the body can break down and absorb a specific protein.
- Amino Acid Composition: The types and proportions of amino acids present in a protein.
Protein Quality
- Animal proteins: Generally, more digestible than plant proteins.
- Plant proteins: Can be less digestible, but some legumes like soybeans are exceptions.
- Limiting amino acid: The essential amino acid present in the lowest amount relative to the body's needs.
- High-quality proteins: Provide all essential amino acids in proportions required for optimal human health.
Complementary proteins
- Combining plant proteins that contain different amino acid profiles can create a complete protein that supplies all essential amino acids.
Health Effects and Recommendations
- Protein does not seem to increase the risk of cancer, although certain protein-rich foods like processed meats are associated with higher cancer risk.
- The World Health Organization (WHO) classifies processed meat as a carcinogen and red meat as a probable carcinogen.
- Soy protein may offer protection against breast cancer, but not endometrial cancer.
- Protein intake and bone health:
- High protein intake may increase calcium excretion, but the effect on bone health depends on calcium intake.
- Adequate calcium is important for bone health, even with high protein intake.
Protein and Weight Management
- High-protein diets can lead to weight loss due to their lower calorie content and ability to increase feelings of fullness.
- Diets emphasizing moderate amounts of high-quality protein at each meal might optimize protein synthesis and muscle health.
Protein and Kidney Disease
- High protein intake increases the workload on the kidneys, but it does not cause kidney disease.
- In individuals with chronic kidney disease, restricting dietary protein, particularly red meat, can slow the progression of the disease.
Recommended Intake
- Adults require 0.8 grams of protein per kilogram of healthy body weight per day.
- Infants and children have higher protein requirements.
- The average protein intake in the United States is 80 grams per day.
- Some research suggests slightly higher protein intake might be beneficial, especially for older adults.
- To ensure adequate intake, aim for 25-35 grams of high-quality protein with each meal.
From Guidelines to Groceries
- Protein Foods:
- An ounce of protein-rich food provides approximately 7 grams of protein.
- The USDA Food Patterns encourage a variety of protein sources over the week:
- 20% from seafood
- 70% from meat, poultry and eggs
- 10% from nuts, seeds and legumes
- Milk and Milk Products: Also provide significant protein quantities per serving.
Proteins and Amino Acids
- Proteins are composed of carbon, hydrogen, oxygen, and nitrogen, arranged into amino acids linked in a chain.
- Some amino acids also contain sulfur atoms
- The human body can make nonessential amino acids (dispensable amino acids) given nitrogen and fragments from fats or carbohydrates.
- Essential amino acids (indispensable amino acids) must be obtained from the diet because the body cannot make them.
- Nine essential amino acids are needed by the human body
- A conditionally essential amino acid is an amino acid that is normally nonessential but must be supplied by the diet in special circumstances.
- An example of a conditionally essential amino acid is tyrosine - the body normally uses phenylalanine to make tyrosine, if the diet lacks phenylalanine or the body cannot make the change (like in the disorder phenylketonuria) then tyrosine becomes conditionally essential.
- Condensation reactions create peptide bonds between amino acids to form a dipeptide.
- The primary structure of a protein is determined by the sequence of amino acids along the polypeptide chain.
- The 20 different amino acids can be arranged in any sequence, and therefore form a wide variety of proteins.
- Protein digestion begins in the stomach using hydrochloric acid and pepsin which breaks proteins into smaller polypeptide chains.
- Pepsinogen is converted to its active form, pepsin, by hydrochloric acid.
- In the small intestine, pancreatic and intestinal proteases further break down polypeptides into shorter chains, tripeptides, dipeptides, and amino acids.
- Peptidase enzymes on the intestinal cell membranes split most dipeptides and tripeptides into single amino acids.
- Specific carriers transport amino acids into intestinal cells.
- Amino acids can be used for energy or synthesized into needed compounds within the intestinal cells.
- Excess amino acids are transported across the cell membrane into the surrounding fluid and then into the capillaries on their way to the liver.
Protein Quality
- Combining different protein foods at a meal can create a "complete protein", meaning it has all the essential amino acids in the optimal ratio.
- For most healthy vegetarians, combining proteins at each meal is not necessary, as long as protein intake is varied throughout each day.
Protein Deficiency
- Protein deficiency is caused by too little dietary protein or by a lack of essential amino acids.
- In protein deficiency, the synthesis of body proteins decreases and degradation increases to provide cells with the amino acids they need.
- This can lead to slowed growth, impaired brain and kidney function, poor immunity, and inadequate nutrient absorption.
Excess Protein Intake
- Excess protein intake has been linked to heart disease, especially if the protein comes from animal sources.
- Many people in developed countries consume more protein than they need.
- The average intake of protein in the United States is 80 grams per day, while the recommended intake is 50-175 grams per day depending on individual needs.
- Moderate amounts of high-quality protein at each meal (25-35 grams) may better support protein synthesis and muscle health.
Protein RDA
- The protein RDA for adults is 0.8 grams per kilogram of healthy body weight per day.
- The RDA is slightly higher for infants and children.
Protein Food Groups
- An ounce of most protein foods delivers about 7 grams of protein.
- The USDA Food Patterns suggest the following breakdown for protein sources:
- 20% seafood
- 70% meat, poultry, and eggs
- 10% nuts, seeds, and legumes
- One serving (a cup) of milk or yogurt provides about 8 grams of protein.
- Fruits do not contain protein.
- A serving of vegetables provides 2-3 grams of protein.
- A serving of grains provides 2-3 grams of protein.
- Food labels should state the total protein in grams per serving.
- The "Percent Daily Value" for protein is required on food labels that make a protein claim or are intended for children under 4 years old.
Protein Supplements
- Protein powders are commonly used by athletes, dieters, and those looking to enhance their nail health.
- Individual amino acids are also marketed to cure herpes, improve sleep, aid in weight loss, and relieve pain and depression.
- Protein and amino acid supplements are popular but do not offer miraculous health benefits.
- Protein powders may be helpful for athletes who engage in resistance training but the evidence is not conclusive.
The Chemist’s View of Proteins
- Proteins contain carbon, hydrogen, oxygen, and nitrogen atoms, arranged into amino acids linked in a chain.
- Some amino acids also contain sulfur atoms.
- Nonessential amino acids are dispensable, meaning the body can make them.
- The body's synthesis of nonessential amino acids requires nitrogen to form the amino group and fragments from carbohydrate or fat to form the rest of the structure.
Amino Acids
- Essential amino acids are indispensable, meaning the body requires them from diet.
- The human body either cannot make nine essential amino acids at all or cannot make them in sufficient quantity.
Conditionally Essential Amino Acids
- A conditionally essential amino acid is normally nonessential but becomes essential under specific circumstances.
- The body normally uses the essential amino acid phenylalanine to make tyrosine.
- If the diet fails to supply enough phenylalanine, or the body cannot make the conversion, tyrosine becomes a conditionally essential amino acid.
Condensation of Two Amino Acids to Form a Dipeptide
- Condensation reactions connect amino acids together to form a dipeptide.
- A peptide bond connects the acid end of one amino acid with the amino end of another, forming a link in a protein chain.
Primary Structure—Amino Acid Sequence
- The primary structure of a protein is determined by the sequence of amino acids.
- Each amino acid in a polypeptide chain is one of 20 different amino acids.
- Amino acid sequences within proteins vary.
- If an essential amino acid is missing, cells must dismantle their own proteins to obtain it.
- To prevent protein breakdown, dietary protein must supply all nine essential amino acids plus enough nitrogen-containing amino groups and energy for the synthesis of nonessential amino acids.
Protein in Foods
- The quality of a food protein is determined by comparing its amino acid composition with the essential amino acid requirements of preschool-age children.
- This standard is called a reference protein.
- Limiting amino acid refers to the essential amino acid found in shortest supply relative to the amounts needed for protein synthesis.
- Lysine, methionine, threonine, and tryptophan are limiting amino acids.
High-Quality Proteins
- A high-quality protein contains all the essential amino acids in relatively the same amounts and proportions as human needs.
- Proteins low in an essential amino acid cannot support protein synthesis on their own.
- Animals sources (meat, seafood, poultry, eggs, and milk) provide high-quality proteins except gelatin.
High-Quality Proteins Continued
- Plant-derived proteins have more diverse amino acid patterns and tend to be limiting in one or more essential amino acids.
- Some plant proteins, such as corn protein, are notoriously low quality, while others, like soy protein, are high quality.
Complementary Proteins
- Plant proteins are lower quality than animal proteins, and plants also offer less protein.
- Vegetarians improve the quality of protein in their diets by combining plant-protein foods that have complementary amino acid patterns.
- This combination creates complementary proteins containing all the essential amino acids in sufficient quantities.
- The protein quality of the combination is greater than either food alone.
- Balancing amino acids at each meal is not necessary if protein intake is varied and energy intake is sufficient.
Health Effects and Recommended Intakes of Protein
- Protein deficiency develops when the diet consistently supplies too little protein or lacks essential amino acids.
- When protein deficiency occurs, the synthesis of body proteins decreases, and degradation increases to provide cells with amino acids.
- Consequences of protein deficiency include slowed growth, impaired brain and kidney functions, poor immunity, and inadequate nutrient absorption.
Heart Disease
- Protein is so abundant in the United States that problems of excess are more common than deficiency.
- A high-protein diet may contribute to the progression of heart disease depending on the food source.
- Replacing animal protein with vegetable protein (legumes and nuts) and using low-fat milk, poultry, and fish may improve blood pressure, blood lipids, and decrease heart disease mortality.
Heart Disease Continued
- Elevated homocysteine in heart disease is unclear in its role as a risk factor, but it may be a marker for free radical oxidation.
- Lowering homocysteine using B vitamin supplements, especially folate, does not seem to lower the risks of heart attacks, strokes, or sudden death.
- Arginine may help protect against heart disease by lowering blood pressure and preventing blood clots.
- Restricting dietary protein, especially red meat, helps slow the progression of kidney disease.
Recommended Intakes of Protein
- The body continuously breaks down and loses some protein, and it cannot store proteins or amino acids.
- The body needs dietary protein to replace lost protein and obtain essential amino acids.
- Dietary protein is the most practical source of nitrogen for building nonessential amino acids and other nitrogen-containing compounds.
Recommended Intakes of Protein Continued
- Protein should constitute 10 to 35 percent of total food energy.
- In a 2000-kcalorie diet, that represents 200 to 700 kcalories from protein, or 50 to 175 grams.
- The average intake in the United States is 80 grams per day.
- Some research suggests that an intake slightly higher than current recommendations may be beneficial, especially for older adults.
- Including moderate amounts (25–35 grams) of high-quality protein at each meal may best support protein synthesis and muscle health.
Protein RDA
- The protein RDA for adults is 0.8 gram per kilogram of healthy body weight per day.
- For infants and children, the RDA is slightly higher.
From Guidelines to Groceries
- An ounce of most protein foods delivers about 7 grams of protein.
- The USDA Food Patterns encourage a variety of protein sources.
- Over a week’s time, the total recommended intake of protein foods should be about 20% seafood, 70% meat, poultry, and eggs, and 10% nuts, seeds, and legumes.
Milk and Milk Products
- The only other food group to provide significant amounts of protein per serving is the milk and milk products group.
- A serving (a cup) of milk or yogurt provides about 8 grams of protein.
Fruits, Vegetables, and Grains
- Fruits do not contain protein.
- A serving of vegetables provides 2-3 grams of protein, and a serving of grain provides 2-3 grams.
Read Food Labels
- Food labels state the quantity of protein in grams.
- The “% Daily Value” for protein is not mandatory on all labels but is required whenever a food makes a protein claim or is intended for children younger than 4 years old.
- When the Daily Value percentage is declared, researchers must determine the quality of the protein.
- The % Daily Value for protein reflects both quantity and quality.
Read Food Labels Continued
- Six ounces of grains provide about 18 grams of protein; 2½ cups of vegetables deliver about 10 grams; 3 cups of milk offer 24 grams; and 5½ ounces of protein foods supply 38 grams.
- This totals 90 grams of protein - higher than the protein RDA for most people.
- People in the United States typically get more protein than they need.
- The key diet-planning principle to emphasize for protein is moderation.
Protein and Amino Acid Supplements
- Protein powders are taken by athletes to build muscle, dieters to spare their bodies' protein, and women to strengthen fingernails.
- Individual amino acids are taken for various reasons, including curing herpes, improving sleep, weight loss, relieving pain, and alleviating depression.
- Protein and amino acid supplements do not offer miracles.
- The body builds muscle protein from amino acids.
Protein Powders
- Athletes frequently take protein powders after exercising, especially after resistance training, to promote protein synthesis and muscle strength.
- Whether this enhanced protein synthesis actually builds muscle or improves performance is unclear.
- Protein supplements remain popular, as they are relatively safe and inexpensive.
Vitamins & Minerals
- The body needs 13 vitamins and 22 minerals to function.
- Vitamins are categorized as water-soluble or fat-soluble.
- Fat-soluble vitamins include A, D, E, and K.
- Excess fat-soluble vitamins are stored in the liver and body fat.
- Vitamin A promotes good vision, healthy skin, and bone, teeth, and cell structure growth.
- The RDA for vitamin A is 900 micrograms for men and 700 micrograms for women.
- Too much vitamin A turns skin orange and may cause fatigue, weakness, headache, hair loss, joint pain, liver or brain damage, and birth defects.
- Too little Vitamin A causes night blindness and lowers the immune system.
- Vitamin A is found in animal products like liver, eggs, milk, butter, and cheese.
- Carotenoids, found in yellow and orange fruits and vegetables, are converted to vitamin A.
- Carotenoids are also found in leafy greens.
- Vitamin D is essential for building and maintaining bones and teeth.
- Vitamin D is responsible for calcium absorption and utilization.
- Vitamin D may boost the immune system and help decrease certain cancers.
- The RDA for vitamin D is 5 micrograms until age 50, 10 micrograms until age 70, and 15 micrograms after age 70.
- Vitamin D deficiency is common, especially in individuals following a vegetarian or lactose-free diet, those with limited sun exposure, or those with difficulty absorbing vitamin D.
- Vitamin D deficiency may cause osteomalacia or osteoporosis.
- Vitamin D can be obtained through sun exposure, fortified milk, tuna, and salmon.
- Vitamin E is important for red blood cells, muscles, and tissues.
- Vitamin E deficiency is rare, and toxicity is also rare.
- Vitamin E acts as a blood thinner.
- Vitamin E is found in vegetable oils, salad dressings, whole grains, green leafy vegetables, nuts, seeds, peanut butter, and wheat germ.
- Vitamin K is essential for blood clotting and bone health.
- Vitamin K is primarily produced in the intestines.
- Vitamin K is found in turnip greens, cauliflower, spinach, liver, broccoli, kale, and cabbage.
- Water-soluble vitamins include vitamin Bs and vitamin C.
- The eight B vitamins are thiamin, riboflavin, niacin, pyridoxine, cobalamin, folic acid, pantothenic acid, and biotin.
- Thiamin, or B1, is crucial for converting carbohydrates to energy.
- Thiamin deficiency causes Fatigue, nausea, depression, and nerve damage.
- Thiamin is found in beef, liver, peas, seeds, legumes, whole grains, and oatmeal.
- Riboflavin, or B2, is key to metabolism and red blood cell production.
- Riboflavin deficiency causes dry and scaly skin.
- Riboflavin is found in milk, yogurt, cheese, whole-grain bread, green leafy vegetables, meat, and eggs.
- Niacin, or B3, is involved in energy production and is helpful for the skin, nerves, and digestive system.
- Niacin deficiency causes diarrhea, dermatitis, dementia, and death.
- Niacin is found in meat, poultry, liver, eggs, brown rice, baked potatoes, fish, milk, and whole grains.
- Pyridoxine, or B6, is involved in protein and amino acid chemical reactions.
- Pyridoxine deficiency causes skin changes, dementia, nervous system disorders, and anemia.
- Pyridoxine is found in lean meats, fish, legumes, green leafy vegetables, raisins, corn, bananas, and mangos.
- Cobalamin, or B12, is essential for nervous system function, red blood cell production, and DNA synthesis.
- Cobalamin deficiency causes nervous system disorders and pernicious anemia.
- Cobalamin is only found in animal products.
- Cobalamin is found in meat, fish, poultry, eggs, milk products, and clams.
- Folic acid, or folate, plays a key role in red blood cell formation and cell division.
- Folic acid deficiency causes anemia and digestive disorders.
- Folic acid is found in leafy, dark green vegetables, liver, beans, peas, oranges, and avocados.
- Pantothenic acid and biotin aid the metabolism and the formation of some hormones.
- Deficiencies of pantothenic acid and biotin are rare.
- They are found in almost all foods, plant-based or animal-based.
- Vitamin C is important for bone health, blood vessel health, cell structure, and iron absorption.
- Vitamin C deficiency is rare.
- Vitamin C is found in melons, berries, tomatoes, potatoes, broccoli, fortified juices, kiwi, mangos, yellow peppers, and citrus fruits.
- There are 22 minerals needed by the body.
- Minerals are categorized into major and trace minerals.
- Major minerals are calcium, chloride, magnesium, phosphorus, potassium, sodium, and sulfur.
- Trace minerals are iron, zinc, iodine, selenium, copper, manganese, fluoride, chromium, molybdenum, arsenic, nickel, silicon, boron, and cobalt.
- Sodium helps maintain fluid balance, transmits nerve impulses, and influences muscle contraction and relaxation.
- Too much sodium causes high blood pressure and can lead to fluid retention.
- The human body requires 500mg of sodium per day, but the average American consumes between 2,300- 6,900mg.
- The recommended daily intake of sodium is 1,500 to 2,400mg.
- Reducing sodium intake can be achieved by eating more fresh foods, less processed foods, low-sodium products, and using alternative seasonings.
- Calcium is the most abundant mineral in the body.
- 99% of calcium is stored in the bones.
- Calcium is important for bone health.
- The RDA for calcium is 1,000mg per day for males and females aged 19 to 50 years old.
- Rich sources of calcium include dairy products, fortified juices, and sardines.
- Iron deficiency is the most common vitamin/mineral deficiency worldwide.
- 70% of the body's iron is in hemoglobin, which carries oxygen.
- Iron deficiency results in low oxygen levels in the body.
- Iron is categorized as heme and non-heme iron.
- Heme iron is found in animal products, specifically red meats, liver, poultry, and eggs.
- Non-heme iron is found in plants, including beans, nuts, seeds, dried fruits, and fortified bread and cereals.
- Iron supplements should be taken under the guidance of a medical professional.
Analytical Chemistry
- Analytical chemistry deals with characterizing the composition of matter, both qualitatively and quantitatively.
- It involves identifying the types of substances present and how much of each there is.
- The field focuses on improving experimental design, developing new measurement tools to provide better chemical information, and applying mathematical and statistical methods to analyze data (chemometrics).
- It has applications in forensics, bioanalysis, clinical analysis, environmental analysis, and materials analysis.
Constituent Analysis
- A constituent is a component of a sample.
- A major constituent corresponds to 1-100% of the sample.
- A minor constituent corresponds to 0.01-1% of the sample.
- A trace constituent is present in a very small amount, below 0.01%.
Quantitative Analysis
- Refers to determining the amount of a specific substance (analyte) present in a sample.
- A sample is a limited quantity intended to represent a larger amount of the same material.
- The analytes are the components of interest in the sample.
- The remaining parts of the sample are termed the matrix.
- A procedure specifies the written instructions for applying a method to a particular sample.
- Techniques are chemical or physical principles used for analysis while a method is the application of a technique to a specific analyte in a particular matrix.
- A technique or reaction is specific if it works for only one analyte.
- A technique or reaction is selective if it works for only a few analytes.
Steps in a Typical Quantitative Analysis
- Select a method: Choosing a method based on desired accuracy, reliability, time constraints, cost, and sample complexity.
- Sampling: Acquiring a representative sample, which is crucial for mass products.
- Sample preparation and handling: This involves dissolving or digesting samples, avoiding decomposition, and preparing solid samples by grinding them to a suitable particle size for homogeneity.
- Define replicate samples: Replicate samples are portions of the same material carried through the analytical procedure at the same time to ensure accuracy, reliability, and cost-effectiveness.
- Eliminating interferences: An interference is a species that affects the measurement by enhancing or attenuating (reducing) the analyte's signal. Blanks are used for control.
- Calibration and measurement: Calibration is a process to establish the exact relationship between the measured property and the desired property using a calibration curve (typically y=mX+b).
- Calculation and data reduction: Determining the relationship between the measured property and the desired property.
- Evaluating results and estimating reliability: Statistical methods are used to evaluate the reliability, as an analytical result without an estimate of reliability is of no value.
Types of Analysis
- Qualitative analysis: Determines the identity of the chemical species in a sample.
- Quantitative analysis: Determines the amount of one or more components in the sample.
- Fundamental analysis: Improves an analytical method's capabilities.
- Characterization analysis: Evaluates a sample's chemical or physical properties.
Classical Methods
- Also known as "wet chemistry" methods, they use chemicals for separation, precipitation, extraction, and qualitative analysis based on color, odor, or melting point.
Instrumental Methods
- Utilize instruments to measure physical quantities of the analyte, such as light absorption, fluorescence, or conductivity.
- Examples include spectroscopy, electrochemistry, and chromatography.
Analytical Chemistry Course Information
- University of Jordan, Department of Chemistry, Analytical Chemistry course (0303211)
- Textbook: Fundamentals of Analytical Chemistry by Skoog, West, Holler, and Crouch (9th Edition, 2004)
- Grading System: First exam (30 marks), Second exam (30 marks), Final exam (40 marks)
- Total marks: 100
Course Outline
- The Nature of Analytical Chemistry (Chapter 1): Discusses the fundamentals of analytical chemistry.
- Calculations Used in Analytical Chemistry (Chapter 4): Covers calculations commonly used in analytical chemistry.
- Errors in Chemical Analysis (Chapter 5): Examines systematic errors in analytical chemistry.
- Random Errors in Chemical Analysis (Chapter 6): Addresses random errors, statistical treatment of random errors, standard deviation, and reporting computed data.
- Statistical Data Treatment and Evaluation (Chapter 7): Covers confidence intervals and detection of gross errors.
- Aqueous Solutions and Chemical Equilibria (Chapter 9): Classifies solutions of electrolytes, chemical equilibrium, and buffer solutions.
- Effect of Electrolytes on Chemical Equilibria (Chapter 10): Discusses the impact of electrolytes on chemical equilibria, activity coefficients.
- Solving Equilibrium Problems for Complex Systems (Chapter 11): Solves equilibrium problems using a systematic method, examines the solubility of metal hydroxides, and explores the separation of ions by controlling the concentration of the precipitating agent.
- Gravimetric Methods of Analysis (Chapter 12): Focuses on precipitation gravimetry, calculating results from gravimetric data, and applications of gravimetric methods.
- Titrimetric Methods; Precipitation Titrimetry (Chapter 13): Explains terms used in volumetric titrimetry, standard solutions, volumetric calculations, gravimetric titrimetry, and precipitation titrimetry.
- Principles of Neutralization Titrations (Chapter 14): Covers solutions and indicators for acid/base titrations, titration of strong acids and bases, titration curves for weak acids and bases, and the composition of solutions during acid/base titrations.
- Complexation Reactions and Titrations (Chapter 17): Explains the formation of complexes, titrations with inorganic complexing agents, organic complexing agents, and aminocarboxylic acid titrations.
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Explore the role of protein in daily nutrition, its sources, and the importance of moderation. Understand the various protein supplements and their uses among different demographics, including athletes and dieters. This quiz covers essential information on dietary allowances and protein powders' impacts.