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Questions and Answers
What defines the specific function of a protein?
What defines the specific function of a protein?
Which amino acid is classified as non-essential?
Which amino acid is classified as non-essential?
What type of bond connects amino acids in a protein?
What type of bond connects amino acids in a protein?
Which of the following amino acids is synthesized from serine?
Which of the following amino acids is synthesized from serine?
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During digestion, which enzyme class is responsible for breaking down dietary proteins?
During digestion, which enzyme class is responsible for breaking down dietary proteins?
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What is the primary factor that limits protein synthesis when there is an inadequate supply of dietary amino acids?
What is the primary factor that limits protein synthesis when there is an inadequate supply of dietary amino acids?
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Which food source is generally known to provide complete proteins?
Which food source is generally known to provide complete proteins?
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What does Biological Value (BV) measure in proteins?
What does Biological Value (BV) measure in proteins?
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What is the function of deamination in protein metabolism?
What is the function of deamination in protein metabolism?
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Which of the following is NOT a component that can be lost in fecal matter related to nitrogen balance?
Which of the following is NOT a component that can be lost in fecal matter related to nitrogen balance?
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In protein efficiency ratio (PER), what does the term 'gain in weight' primarily refer to?
In protein efficiency ratio (PER), what does the term 'gain in weight' primarily refer to?
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Which characteristic distinguishes complete proteins from incomplete proteins?
Which characteristic distinguishes complete proteins from incomplete proteins?
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What is the significance of the chemical score in evaluating protein quality?
What is the significance of the chemical score in evaluating protein quality?
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Study Notes
Proteins: Macronutrients
- Proteins are essential for growth, metabolism, and energy production.
- Proteins are long chains of amino acids in a specific sequence.
- The sequence and subsequent structure give proteins their function.
- Amino acids link together to form dipeptides, tripeptides, oligopeptides, and polypeptides.
- Amino acid side chains vary greatly, leading to different amino acids (AAs).
- Interactions between side chains shape protein structure.
- Proteins are essential for various bodily functions, including growth, metabolism, and energy.
- There are 9 essential amino acids that the body cannot produce on its own.
- Incomplete proteins are plant-based sources that may lack one or more essential amino acids.
- Complete proteins contain all essential amino acids in adequate amounts, such as animal products and some plant sources.
- Complementary proteins combine incomplete protein sources to provide all essential amino acids.
- Protein requirements vary depending on age, sex, and health conditions.
- The recommended daily intake (RNI) for protein is 0.75g per kilogram of body weight per day.
Amino Acid Structure
- Amino acids have an amino group, a carboxyl group, a hydrogen atom, and a variable side chain (R group).
- The R group determines the unique properties of each amino acid.
Amino Acids Examples
- Specific examples of amino acids like Tyrosine (Tyr), Asparagine (Asp), and Valine (Val) are shown.
Amino Acid Classification
- Amino acids are categorized as essential, non-essential, or conditionally essential, based on the body's ability to synthesize them.
- Examples of Essential amino acids include Histidine, Isoleucine, Leucine, Lysine, Methionine, Phenylalanine, Threonine, Tryptophan, and Valine.
Origin of Non-Essential Amino Acids
- Non-essential amino acids are derived from metabolic intermediates, such as pyruvate or intermediates in the citric acid cycle.
- Specific examples such as Alanine, Asparagine, Arginine, Glutamine, Proline, Serine, Glycine, Cysteine, and Tyrosine are derived from these precursors.
Protein Digestion
- Dietary proteins are broken down into individual amino acids by peptidases.
- The amino acids enter the body pool for various metabolic processes.
- Transamination and deamination are involved in protein metabolism, with deamination converting protein into fuel.
Nitrogen Balance
- Nitrogen balance is the difference between protein intake and protein output in the body.
- Dietary protein intake provides nitrogen, while urine excretion removes unused nitrogen.
- Factors like body protein turnover, faecal loss, and metabolism affect nitrogen balance.
Protein Quality
- Protein quality is determined by its digestibility and amino acid composition.
- Biological value (BV) measures the proportion of absorbed protein retained in the body.
- Protein efficiency ratio (PER) measures the gain in body weight per gram of protein consumed.
- Net protein utilisation (NPU) considers both protein digestibility and utilisation in the body.
- Chemical score compares the amount of limiting amino acid in a food to the same in a reference protein (egg protein).
- Protein score is similar to chemical score but compares against a reference pattern.
Complete Protein Sources
- Complete proteins contain all essential amino acids (e.g., meat, fish, dairy products, some plant sources like soya, quinoa, and mycoprotein).
Limiting Amino Acids
- Limiting amino acid is the essential amino acid present in the least amount in a protein source, restricting protein synthesis if insufficient.
- Specific examples of limiting amino acids present in different food sources are illustrated.
Protein Sources
- Different food sources provide protein (meat, fish, beans, pulses, dairy products).
- Pulses and beans are good sources of fiber.
- Dairy products are excellent sources of calcium and other essential vitamins.
Protein Requirements
- The recommended daily allowance (RDA) of protein is 0.75 g/kg of body weight per day.
- Protein requirements vary depending on age, sex, physical activity, and health conditions
National Diet and Nutrition Survey Intakes
- NDNS (2019) data show typical protein intake for men and women.
Protein Content of Selected Foods
- Detailed protein content is provided for various food types (meat, fish, dairy, plant-based sources).
Summary
- Crucial point for protein digestion and metabolism and its importance for overall health.
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Description
Explore the essential roles of proteins in growth, metabolism, and energy production. Learn about the various types of amino acids, how they form proteins, and the importance of complete and incomplete proteins in your diet. This quiz will delve into the unique structures and functions proteins serve in the body.
