Questions and Answers
Which of the following fates do amino acids and peptides NOT experience after absorption in the small intestine?
What is a key characteristic of Kwashiorkor?
Which protein source is NOT associated with a higher risk of heart disease?
How does high protein intake potentially affect calcium levels in the body?
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Which of the following statements regarding protein powders is correct?
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What protein intake recommendation percentage is advised for total food energy?
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In terms of protein-energy malnutrition, Marasmus is primarily characterized by which factor?
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Which statement regarding protein and cancer risk is accurate?
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How should dietary protein be adjusted in individuals with chronic kidney disease?
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What should the ideal calcium-to-protein intake ratio be to ensure bone health?
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Study Notes
Overview of Protein
- Essential component of every living cell in plants, animals, and microorganisms.
- Composed of amino acids and nitrogen; these are the building blocks formed during protein digestion.
Amino Acids
- Joined by peptide bonds to create various proteins.
- Classified into essential and non-essential amino acids.
- Non-essential amino acids can be synthesized by the body, while essential amino acids (9 total) must be obtained through diet.
Types of Proteins by Structure
- Simple Proteins: Hydrolyze to yield only amino acids (e.g., Albumins, Globulins).
- Complex Proteins: Composed of simple proteins and additional non-protein groups (e.g., Glycoproteins, Phosphoproteins).
- Derived Proteins: Formed from degradation products like peptides.
Protein Sources
- Complete Proteins: Contain all essential amino acids; primarily from animal sources (e.g., meats, dairy).
- Partially Complete Proteins: Contain some essential amino acids but are insufficient for growth; examples include certain fish.
- Incomplete Proteins: Low in one or more essential amino acids; typically from plant sources (e.g., grains, cereals).
Functions of Proteins
- Tissue Building: Essential for repair and growth.
- Energy Source: Can be used when carbohydrates and fats are insufficient.
- Plasma Proteins: Maintain osmotic balance in blood (e.g., Albumin).
- Defense Mechanisms: Essential for immune response; antibodies are proteins.
Protein in Acid-Base Balance
- Proteins act as buffers by attracting and releasing hydrogen ions (H+) to maintain pH levels (normal range: 7.35 - 7.45).
Protein Transport Functions
- Some proteins carry nutrients and facilitate oxygen transport via hemoglobin.
- Lipoproteins transport lipids; other proteins can act as membrane pumps for transporting vitamins and minerals.
Fluid Balance Regulation
- Proteins generally remain in blood vessels; however, during illness or malnutrition, they may leak, attracting water and causing edema (swelling).
Digestion and Absorption of Proteins
- Begins in the stomach, where protein is hydrolyzed into polypeptides by HCL and enzymes; further cleaved by pancreatic enzymes.
- Amino acids are absorbed in the small intestine and can either enter circulation, convert to other amino acids, or provide energy.
Protein in Food
- Sources include casein in milk, albumin in egg whites, and gluten in wheat.
Protein Deficiency
- Protein-energy malnutrition (PEM): Insufficient dietary protein leads to conditions like Kwashiorkor and Marasmus.
- Kwashiorkor: Characterized by edema, muscle weakness, and brittle hair due to severe protein deficiency.
- Marasmus: Results from lack of energy and protein, leading to extreme weakness, muscle wasting, and growth retardation.
Health Implications of Protein Intake
- High animal protein intake may increase heart disease risk due to saturated fats.
- Plant proteins may lower risks of certain cancers, while high intakes of red and processed meats are linked to some cancers.
- High protein intake may increase calcium excretion, affecting bone health; a calcium-to-protein ratio of > 20:1 is deemed protective.
- High protein diets increase workload on kidneys, which could accelerate deterioration in those with chronic kidney disease.
Protein Recommendations
- Protein intake should constitute 10-35% of total energy.
- Recommended dietary allowance (RDA) for adults: 0.8 g/kg of body weight; higher for infants/children.
Protein Powders
- Commonly used by athletes to enhance muscle growth, but muscle building requires physical activity rather than supplementation alone; excessive protein does not necessarily yield greater muscle growth.
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Description
Explore the essential components of proteins and their relationship with amino acids in this quiz. Discover the distinctions between essential and non-essential amino acids, and understand the fundamental role proteins play in all living cells. Test your knowledge and deepen your understanding of this vital topic.
