33 Questions
What percentage of the body's energy needs does the brain use at rest?
~35%
Which amino acids are used to supply glucose during times of low carbohydrate intake and low blood glucose levels?
Glucogenic amino acids
What is the main source of energy for cells?
Fats and carbohydrates
Which food item is the most protein-dense?
Water-packed tuna
What is the function of antibodies in the body?
Respond to foreign invaders in the body
What happens when there is inadequate protein intake?
The function of the immune system is compromised
What is the energy content of proteins per gram?
4 kcal/gram
Which component do proteins not store in the body unlike carbohydrates and fats?
Energy
What are the repeating units of proteins made of?
Amino acids
Which aspect of proteins contributes to immune function?
Contribution to body fluid balance
What is the primary function of enzymes, a type of protein?
Speeding up chemical reactions
What is the essential amino acid in lowest concentration in a food referred to as?
Limiting aa
What is the recommended percentage of protein intake as essential amino acids for adults?
15%
What can combining plant proteins through mutual supplementation provide?
A full complement of essential amino acids
What is the primary advantage of consuming plant-based protein foods?
Fiber content
What happens to proteins when denaturation occurs?
Altered 3-D shape and loss of function
What percentage of protein intake as essential amino acids do infants and preschoolers require to support growth?
32-43%
How are di- and tri-peptides absorbed into intestinal cells?
By different carriers than those used for single amino acids
What happens to intact proteins in adult life under normal conditions?
They do not get absorbed into the bloodstream
Which factor influences protein quality?
Completeness and amino acid profile relative to human needs
What is the role of blood proteins such as albumin and globulins?
Maintain body fluid balance
What happens in food allergy compared to food intolerance?
Involves an immune response to a protein in food
How are proteins in cell membranes involved in nutrient absorption?
Act as receptors, pumps, and carriers for absorption of nutrients into cells
Which amino acid is considered essential and cannot be synthesized in sufficient quantities by the body?
Histidine
Where does deamination, the loss of an amino group from an amino acid, primarily occur?
Liver
What determines the quality of dietary proteins?
Nitrogen retention and support for body growth
What do complete proteins provide in adequate quantities?
All essential amino acids
Which type of amino acids can become conditionally essential under certain conditions?
$ ext{Non-essential}$ amino acids
What is the main function of proteins in the structure of muscles, tendons, ligaments, hair, skin, and nails?
Provide structural support and integrity
What is a key principle to follow for weight loss strategies?
Adequacy, balance, kcalorie control, moderation, and variety
What is the recommended lower limit for daily calorie intake to avoid restricted food selections?
~1500-1800 kcal/day
What is a proposed way to attain a desirable BMI according to the text?
Increase physical activity to a moderately intense level
What should be avoided in the pursuit of weight loss according to the text?
"Quick fix" herbal or other remedies marketed for weight loss
Study Notes
Amino Acids and Proteins: Key Concepts
- Proteins are essential for cell repair, hormone production, blood transport, immune function, and the structure of muscles, tendons, ligaments, hair, skin, and nails.
- They supply nitrogen in a form usable by humans and are found in both plant and animal sources.
- Proteins constitute a major part of lean body mass, including muscle, bone, organs, connective tissue, and skin.
- The quantity and quality of dietary protein sources need to be considered.
- Amino acids, the building blocks of proteins, contain carbon, hydrogen, oxygen, and nitrogen, with some also containing sulfur atoms.
- Different side chains in amino acids result in different properties for each amino acid.
- Essential amino acids, which cannot be synthesized in sufficient quantities by the body, include histidine, lysine, threonine, and others.
- Non-essential amino acids can be obtained from the diet or synthesized in the body.
- Some amino acids become conditionally essential under certain conditions, such as critical illness.
- Protein turnover involves the recycling of amino acids in the body, reducing the need for larger quantities of dietary protein.
- Deamination, the loss of an amino group from an amino acid, occurs mostly in the liver and is essential for energy production.
- The quality of dietary proteins is determined by their nitrogen retention and how well they support body growth. Complete proteins, found in animal foods, provide all essential amino acids in adequate quantities.
Test your knowledge on incomplete proteins and mutual supplementation, which involves combining plant proteins to provide a full complement of essential amino acids. Learn about the concept of limiting amino acids and how to ensure vital body protein synthesis continues.
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