15 Questions
Which functional groups are present in all amino acids?
Carboxyl group, amino group, and side chain (R group)
How do GLYCINE and PROLINE differ from the other 20 amino acids?
They are the only amino acids occurring in the L- α form
How are amino acids classified based on chemical classification?
Based on the solubility and ionization at physiological pH as determined by the side chains (R-groups)
What is the function of proteins of high biological value?
Provide essential amino acids in adequate amounts
What is the significance of protein folding/misfolding?
It affects the function of proteins
How many amino acids are occurring in the human body?
20
Which type of amino acids prefer to function in an aquas environment?
Polar neutral amino acids
Which amino acid is purely ketogenic in nature?
Leucine
What occurs in negative nitrogen balance?
Protein malnutrition (kwashiorkor)
Which type of amino acids cannot be synthesized in the human body and must be supplied in the diet?
Essential (indispensable) amino acids
Which group of amino acids is classified as non-essential (dispensable)?
(Non-essential) amino acids that can be synthesized in the human body
Which amino acid has a hydrocarbon or alkyl side chain?
Valine
What do glucogenic amino acids give rise to on catabolism?
(Neutral) amino acids that can be converted into glucose precursors or acetate on catabolism
Which type of amino acids have side chains that contain aromatic side chains?
(Uncharged) hydrophobic amino acids
What happens in positive nitrogen balance?
(Normal) condition in which the amount of nitrogen incorporated into the body each day exactly equals the amount excreted.
Study Notes
Amino Acid Characteristics
- All amino acids have an alpha amino group, a carboxyl group, and a side chain.
- GLYCINE and PROLINE differ from the other 20 amino acids in that they have a secondary amino group and a cyclic structure, respectively.
Amino Acid Classification
- Amino acids are classified into acidic, basic, neutral, and aromatic based on their chemical properties.
Protein Functions
- Proteins of high biological value provide all essential amino acids for human health.
- Proteins are crucial for growth, maintenance, and repair of body tissues.
Protein Folding and Misfolding
- Protein folding is essential for protein function and stability.
- Protein misfolding can lead to various diseases, such as Alzheimer's and Parkinson's.
Amino Acid Occurrence
- There are approximately 20 standard amino acids that occur in the human body.
Amino Acid Preferences
- Hydrophilic (polar) amino acids prefer to function in an aquatic environment.
Ketogenic Amino Acids
- Leucine is purely ketogenic in nature, meaning it is converted to acetoacetate and acetyl-CoA during catabolism.
Nitrogen Balance
- Negative nitrogen balance occurs when the body breaks down more protein than it synthesizes, resulting in muscle wasting.
- Positive nitrogen balance occurs when the body synthesizes more protein than it breaks down, resulting in muscle growth.
Essential Amino Acids
- Essential amino acids cannot be synthesized in the human body and must be supplied in the diet. Examples include phenylalanine, valine, and isoleucine.
Non-Essential Amino Acids
- Non-essential (dispensable) amino acids can be synthesized in the human body from other amino acids. Examples include alanine, aspartic acid, and glutamic acid.
Amino Acid Side Chains
- Amino acids with hydrocarbon or alkyl side chains are classified as non-polar, such as alanine and valine.
Glucogenic Amino Acids
- Glucogenic amino acids give rise to glucose or glucogenic intermediates during catabolism. Examples include glycine and serine.
Aromatic Amino Acids
- Aromatic amino acids have side chains that contain aromatic rings, such as phenylalanine, tyrosine, and tryptophan.
Test your knowledge of amino acid structure, classifications, protein organization, folding, biological value, medically important proteins, and protein functions with this quiz by Dr. Ayat Sayed, Assistant Professor of Medical Biochemistry at Assiut University.
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