38 Questions
What is the precursor of methionine biosynthesis?
Cysteine and Serine
Which of the following amino acids is synthesized via the shikimate pathway?
Tryptophan
What is the origin of the GABA neurotransmitter?
Glutamic acid
Which of the following is a conditionally essential amino acid?
Arginine
What is the pI of the peptide Glu–His–Trp–Ser–Gly–Leu–Arg–Pro–Gly?
7.8
What is the EC number starting with for the enzyme catalyzing the reaction?
1
What is the substrate for the synthesis of epinephrine and norepinephrine?
Tyrosine
Which of the following amino acids is essential?
Leucine
Which of the following is a nonessential amino acid?
Tyrosine
Which of the following amino acids is derived from aspartate?
Asparagine
Which of the following is a polar amino acid?
Histidine
What are the precursors of urea in the liver?
Ammonia and Asp
What is the origin of the acetylcholine neurotransmitter?
Serine
What is the enzyme that catalyzes the conversion of Asp to Asn?
Asparagine synthase
Which of the following is a hormonal protein?
Insulin
What is the origin of the carbon skeleton of serine?
3-phosphoglycerate
At which point in the titration curve does glycine have its maximum buffering capacity?
II and IV
What is the net charge of glycine at point V in the titration curve?
-1
Which amino acid is degraded to form ketone bodies or Krebs cycle intermediates?
Leucine
What is the precursor of proline amino acid?
Arginine
Which enzyme catalyzes the reaction of glutamine synthesis?
Glutamine synthase
Which amino acid is the origin of serotonin neurotransmitter?
Tryptophan
What is the primary function of the enzyme GDH?
To catalyze the oxidative deamination of amino acids
Which amino acid is a nonpolar amino acid?
Phenylalanine
What is the function of GOGAT enzyme?
To convert glutamine to glutamate
Which of the following is a storage protein?
Ovalbumin
What is the role of ion exchange chromatography in amino acid analysis?
To separate amino acids based on their charge
Which amino acid is a nonproteinogenic amino acid?
Desmosine
What is the function of the enzyme GDH in plant cells?
To catalyze nitrogen assimilation
Which of the following is a contractile protein?
Actin
Which amino acid will be eluted first from the cation-exchange column by a pH 7.0 buffer in the pair Asp and Lys?
Asp
Which of the following amino acids is a polar uncharged amino acid?
Asparagine
Which enzyme is involved in the biosynthesis of dopamine from an amino acid?
Tyrosine hydroxylase
Which of the following is a nonpolar amino acid?
Methionine
What is the origin of the carbon skeleton of Leucine amino acid?
Pyrvate
Which amino acid is the substrate for hydroxymethyl transferase to form Glyoxalate?
Serine
Is Threonine biosynthesized in animals from aspartic acid?
true
What is the likely cause of a patient with high blood ammonia levels, elevated glutamine and decreased arginine relative to normal levels?
Deficiency in one of the urea cycle enzymes
Study Notes
Amino Acids
- Valine is a nonessential amino acid.
- Arginine is not a nonessential amino acid.
- Tyrosine is not a nonessential amino acid.
Amino Acid Metabolism
- Urea precursors in the liver are ammonia and aspartate.
- The enzyme that catalyzes the conversion of aspartate to asparagine has two substrates: glutamine and aspartate.
- ADP is an allosteric activator for the catabolic direction of glutamate dehydrogenase (GDH).
Amino Acid Structure and Function
- 6-N-Methyllysine is present in elastin.
- Serine is the origin of acetylcholine neurotransmitter.
- Histidine is converted to histamine by decarboxylation.
- Cysteine precursors are methionine and serine.
- The assimilation of nitrogen in plants in the dark is dependent on the enzyme glutamate dehydrogenase (GDH).
Hormonal Proteins
- Insulin is a hormonal protein.
- Epinephrine is a hormonal protein.
- Vasopressin is a hormonal protein.
Amino Acid Classification
- Aspartic acid is an acidic amino acid.
- Lysine is a basic amino acid.
- Glycine is an achiral amino acid.
- Leucine is a nonpolar amino acid.
Enzyme Reactions
- The enzyme that catalyzes the reaction of asparagine synthetase has an EC number starting with 6.
- The enzyme that catalyzes the conversion of glutamine to glutamate is glutamine synthetase.
Neurotransmitters
- GABA (gamma-aminobutyric acid) neurotransmitter is originated from glutamic acid.
- Serotonin neurotransmitter is originated from tryptophan.
- Dopamine neurotransmitter is originated from tyrosine.
- Epinephrine and norepinephrine synthesis originates from tryptophan.
Protein Structure and Function
- Collagen is a storage protein.
- Ovalbumin is a storage protein.
- Keratin is a contractile protein.
- Actin is a contractile protein.
- Myoglobin is a contractile protein.
Amino Acid Analysis
- Mixtures of amino acids can be analyzed by ion exchange chromatography.
- In a cation-exchange column, amino acids are separated based on ionic attraction and hydrophobic interactions.
Amino Acid Biosynthesis
- Leucine is biosynthesized from 3-phosphoglycerate.
- Proline is biosynthesized from glutamate.
- Serine is a substrate for hydroxymethyl transferase to form glycine.
- Threonine is biosynthesized from aspartic acid.
Quiz on classification and properties of amino acids, including essential and nonessential amino acids, polar and nonpolar amino acids, and their roles in biological processes.
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