Podcast
Questions and Answers
Which of the following is NOT a component of an α-amino acid?
Which of the following is NOT a component of an α-amino acid?
- Carboxylic acid group
- R group
- Amino group
- Hydrogen atom (correct)
At neutral pH, amino acids in solution exist predominantly as:
At neutral pH, amino acids in solution exist predominantly as:
- Unionized molecules
- Dipolar ions (correct)
- Cations
- Anions
Which of the following is true about the optical activity of amino acids?
Which of the following is true about the optical activity of amino acids?
- All amino acids are optically active
- Only α-amino acids are optically active
- Glycine is the only optically active amino acid
- Only amino acids with four different groups connected to the α-carbon are optically active (correct)
Why are cells able to specifically synthesize the L isomers of amino acids?
Why are cells able to specifically synthesize the L isomers of amino acids?
What is the role of proline in peptide chains?
What is the role of proline in peptide chains?
What is the significance of the hydroxyl groups in serine and threonine?
What is the significance of the hydroxyl groups in serine and threonine?
What is the function of glycine in proteins?
What is the function of glycine in proteins?
Which of the following statements about amino acids is NOT true?
Which of the following statements about amino acids is NOT true?
Which of the following amino acids is NOT commonly found in proteins?
Which of the following amino acids is NOT commonly found in proteins?
Which of the following amino acids is optically active?
Which of the following amino acids is optically active?
Which of the following amino acids is NOT hydrophilic?
Which of the following amino acids is NOT hydrophilic?
Which of the following amino acids is an essential amino acid?
Which of the following amino acids is an essential amino acid?
Which of the following amino acids is commonly found in collagen and gelatin?
Which of the following amino acids is commonly found in collagen and gelatin?
Which of the following amino acids has a cyclic structure in its side chain?
Which of the following amino acids has a cyclic structure in its side chain?
Which of the following amino acids has a hydroxyl group in its side chain?
Which of the following amino acids has a hydroxyl group in its side chain?
Which of the following amino acids can engage in H-bonding and ester formation?
Which of the following amino acids can engage in H-bonding and ester formation?
Which of the following amino acids is an important component of the active site of many enzymes?
Which of the following amino acids is an important component of the active site of many enzymes?
Which of the following is true about the structure of an α-amino acid?
Which of the following is true about the structure of an α-amino acid?
Which of the following is true about the R group of an α-amino acid?
Which of the following is true about the R group of an α-amino acid?
What is the predominant form of amino acids in solution at neutral pH?
What is the predominant form of amino acids in solution at neutral pH?
What is the isoelectric point (IEP) of an amino acid?
What is the isoelectric point (IEP) of an amino acid?
Which of the following is true about the optical activity of amino acids?
Which of the following is true about the optical activity of amino acids?
Why are cells able to specifically synthesize the L isomers of amino acids?
Why are cells able to specifically synthesize the L isomers of amino acids?
What is the significance of the hydroxyl groups in serine and threonine?
What is the significance of the hydroxyl groups in serine and threonine?
Which of the following is true about the structure of glycine?
Which of the following is true about the structure of glycine?
What is the role of proline in peptide chains?
What is the role of proline in peptide chains?
What is the function of glycine in proteins?
What is the function of glycine in proteins?
all amino acids of animal proteins are ______ isomers
all amino acids of animal proteins are ______ isomers
D-amino acid residues have been found only in ______ and a few, generally small peptides, including some peptides of bacterial cell walls
D-amino acid residues have been found only in ______ and a few, generally small peptides, including some peptides of bacterial cell walls
D-alanine and D-glutamic acid occur in ______ cell wall
D-alanine and D-glutamic acid occur in ______ cell wall
some antibiotics contain D-______ acids
some antibiotics contain D-______ acids
D-alanine, D-glutamic acid and D-ornithine are present in bacitracin-an active agent against a variety of ______ positive and a few ______ negative bacteria (in vitro)
D-alanine, D-glutamic acid and D-ornithine are present in bacitracin-an active agent against a variety of ______ positive and a few ______ negative bacteria (in vitro)
polymyxins contain D-______
polymyxins contain D-______
why are cells able to specifically synthesize the L ______ of amino acids
why are cells able to specifically synthesize the L ______ of amino acids
the remarkable range of functions exhibited by proteins result from the diversity and versatility of the 20 kinds of building ______-amino acids
the remarkable range of functions exhibited by proteins result from the diversity and versatility of the 20 kinds of building ______-amino acids
glycine (Greek glykos, “sweet”) was so named because of its ______ taste
glycine (Greek glykos, “sweet”) was so named because of its ______ taste
alanine has ______ group as its side chain
alanine has ______ group as its side chain
An α-amino acid consists of a central carbon atom, called the α carbon, an amino group, a carboxylic acid group, a hydrogen atom, and a distinctive ______.
An α-amino acid consists of a central carbon atom, called the α carbon, an amino group, a carboxylic acid group, a hydrogen atom, and a distinctive ______.
The R group is often referred to as the ______.
The R group is often referred to as the ______.
Amino acids in solution at neutral pH are predominantly dipolar ions (Zwitterions) rather than ______ molecules.
Amino acids in solution at neutral pH are predominantly dipolar ions (Zwitterions) rather than ______ molecules.
In the dipolar state, the amino group is ______ and the carbonyl group is ______.
In the dipolar state, the amino group is ______ and the carbonyl group is ______.
The pH at which the net ionic charges are balanced is the ______.
The pH at which the net ionic charges are balanced is the ______.
Amino acids are ______.
Amino acids are ______.
With four different groups connected to the tetrahedral α-carbon atom, α-amino acids are chiral – they are ______.
With four different groups connected to the tetrahedral α-carbon atom, α-amino acids are chiral – they are ______.
The α-carbon of all amino acids are asymmetric, so there are two ______ of each except glycine.
The α-carbon of all amino acids are asymmetric, so there are two ______ of each except glycine.
The two mirror-image forms are called the ______ and ______ isomers.
The two mirror-image forms are called the ______ and ______ isomers.
By convention, if the α-NH3+ is projected to the left, the α-amino acid has an absolute ______ configuration.
By convention, if the α-NH3+ is projected to the left, the α-amino acid has an absolute ______ configuration.
Phenylalanine, tyrosine & tryptophan have ______ side chains
Phenylalanine, tyrosine & tryptophan have ______ side chains
The aromatic side chains make them relatively ______ (hydrophobic)
The aromatic side chains make them relatively ______ (hydrophobic)
All can participate in ______ interactions
All can participate in ______ interactions
Tyrosine and tryptophan are significantly more ______ than phenylalanine
Tyrosine and tryptophan are significantly more ______ than phenylalanine
because of the tyrosine ______ group and the nitrogen of the tryptophan ______ ring
because of the tyrosine ______ group and the nitrogen of the tryptophan ______ ring
Aromatic amino acids are exploited in the ______ of proteins
Aromatic amino acids are exploited in the ______ of proteins
Tyrosine was first isolated from ______ (its name is derived from the Greek tyros, “cheese”)
Tyrosine was first isolated from ______ (its name is derived from the Greek tyros, “cheese”)
Phenylalanine & tyrosine are important constituents of ______
Phenylalanine & tyrosine are important constituents of ______
Are precursors for the synthesis of important regulatory proteins as neurotransmitters and ______
Are precursors for the synthesis of important regulatory proteins as neurotransmitters and ______
Which of the following is true about the aromatic side chains of phenylalanine, tyrosine, and tryptophan?
Which of the following is true about the aromatic side chains of phenylalanine, tyrosine, and tryptophan?
Which of the following amino acids is significantly more polar than phenylalanine?
Which of the following amino acids is significantly more polar than phenylalanine?
Which amino acid can be converted to tyrosine by the enzyme phenylalanine Hydroxylase?
Which amino acid can be converted to tyrosine by the enzyme phenylalanine Hydroxylase?
Which of the following amino acids are important constituents of proteins?
Which of the following amino acids are important constituents of proteins?
Which amino acids are precursors for the synthesis of important regulatory proteins such as neurotransmitters and hormones?
Which amino acids are precursors for the synthesis of important regulatory proteins such as neurotransmitters and hormones?
Which amino acids are the starting point for the synthesis of catecholamines?
Which amino acids are the starting point for the synthesis of catecholamines?
Which enzyme is absent in the congenital disease phenylketonuria?
Which enzyme is absent in the congenital disease phenylketonuria?
Which amino acid was first isolated from cheese?
Which amino acid was first isolated from cheese?
Which amino acids can participate in hydrophobic interactions?
Which amino acids can participate in hydrophobic interactions?
Which of the following statements about amino acids is true?
Which of the following statements about amino acids is true?
Which amino acid is commonly found in collagen and gelatin?
Which amino acid is commonly found in collagen and gelatin?
What is the role of serine and threonine in proteins?
What is the role of serine and threonine in proteins?
Which of the following amino acids is NOT hydrophilic?
Which of the following amino acids is NOT hydrophilic?
Which amino acid is an important reactive amino acid in proteins because the pka of the nitrogen in the imidazole ring of histidyl residues in proteins is in the range of pH of the tissues?
Which amino acid is an important reactive amino acid in proteins because the pka of the nitrogen in the imidazole ring of histidyl residues in proteins is in the range of pH of the tissues?
Which amino acid is an important component of proteins due to the reactivity of the amino group on the side chain?
Which amino acid is an important component of proteins due to the reactivity of the amino group on the side chain?
Which amino acid is the precursor of nitric oxide?
Which amino acid is the precursor of nitric oxide?
Which amino acid has a nonpolar thioether group in its side chain and acts as a methyl donor in biochemical processes?
Which amino acid has a nonpolar thioether group in its side chain and acts as a methyl donor in biochemical processes?
Which of the following amino acids contains a sulfhydryl group in its side chain?
Which of the following amino acids contains a sulfhydryl group in its side chain?
Which amino acid can form a covalent cross-link called a disulfide bond?
Which amino acid can form a covalent cross-link called a disulfide bond?
Which amino acid is a constituent of myosin?
Which amino acid is a constituent of myosin?
Which of the following uncommon amino acids is found in prothrombin (factor II)?
Which of the following uncommon amino acids is found in prothrombin (factor II)?
Which of the following is NOT a type of protein mentioned in the text?
Which of the following is NOT a type of protein mentioned in the text?
Which of the following is the correct formula for haemoglobin mentioned in the text?
Which of the following is the correct formula for haemoglobin mentioned in the text?
What is the function of albumin in the body?
What is the function of albumin in the body?
What does the sedimentation of a protein containing solution indicate?
What does the sedimentation of a protein containing solution indicate?
Which of the following best describes the structure of an α-amino acid?
Which of the following best describes the structure of an α-amino acid?
Which of the following is true about the optical activity of amino acids?
Which of the following is true about the optical activity of amino acids?
Which of the following best describes the predominant form of amino acids in solution at neutral pH?
Which of the following best describes the predominant form of amino acids in solution at neutral pH?
By convention, if the α-NH3+ is projected to the left, the α-amino acid has an absolute ______ configuration.
By convention, if the α-NH3+ is projected to the left, the α-amino acid has an absolute ______ configuration.
Which of the following is NOT a general function of proteins?
Which of the following is NOT a general function of proteins?
Which of the following is a dynamic function of proteins?
Which of the following is a dynamic function of proteins?
Which proteins are involved in enzymatic catalysis?
Which proteins are involved in enzymatic catalysis?
Which proteins are involved in transport of molecules?
Which proteins are involved in transport of molecules?
Which proteins provide structural strength and elasticity to organs?
Which proteins provide structural strength and elasticity to organs?
Which proteins are involved in the control and regulation of gene transcription and translation?
Which proteins are involved in the control and regulation of gene transcription and translation?
Which category do nonpolar, aliphatic amino acids belong to?
Which category do nonpolar, aliphatic amino acids belong to?
What is the general configuration of the peptide bond?
What is the general configuration of the peptide bond?
What are the charged groups present in polypeptides?
What are the charged groups present in polypeptides?
What are proteins classified based on?
What are proteins classified based on?
Which amino acid is an important precursor of the pharmacologically active substance histamine?
Which amino acid is an important precursor of the pharmacologically active substance histamine?
Which amino acid has a lipotropic action and prevents fatty infiltration of the liver?
Which amino acid has a lipotropic action and prevents fatty infiltration of the liver?
What is the most abundant excitatory neurotransmitter in the vertebrate nervous system?
What is the most abundant excitatory neurotransmitter in the vertebrate nervous system?
Which amino acid is involved in the synthesis of urea and stimulates the secretion of insulin and growth hormone?
Which amino acid is involved in the synthesis of urea and stimulates the secretion of insulin and growth hormone?
What is the general structure of an α-amino acid?
What is the general structure of an α-amino acid?
What are the two mirror-image forms of amino acids called?
What are the two mirror-image forms of amino acids called?
What is the predominant form of amino acids in solution at neutral pH?
What is the predominant form of amino acids in solution at neutral pH?
What is the pH at which the net ionic charges are balanced called?
What is the pH at which the net ionic charges are balanced called?
What are the different categories in which amino acids are classified?
What are the different categories in which amino acids are classified?
What is the function of a peptide bond?
What is the function of a peptide bond?
What is the naming convention for a polypeptide?
What is the naming convention for a polypeptide?
What are the charged groups present in polypeptides?
What are the charged groups present in polypeptides?
What is the significance of the hydroxyl groups in serine and threonine?
What is the significance of the hydroxyl groups in serine and threonine?
What is the role of proline in peptide chains?
What is the role of proline in peptide chains?
Which amino acids are commonly found in collagen and gelatin?
Which amino acids are commonly found in collagen and gelatin?
What are the aromatic amino acids and what makes them different from each other?
What are the aromatic amino acids and what makes them different from each other?
What is the role of cysteine in proteins?
What is the role of cysteine in proteins?
What is the difference between cysteine and cystine?
What is the difference between cysteine and cystine?
What are some examples of uncommon amino acids?
What are some examples of uncommon amino acids?
What is the role of methionine and acetylcysteine in the liver?
What is the role of methionine and acetylcysteine in the liver?
What are the properties and functions of proteins?
What are the properties and functions of proteins?
How do proteins fold into three-dimensional structures?
How do proteins fold into three-dimensional structures?
What is the significance of sedimentation in protein analysis?
What is the significance of sedimentation in protein analysis?
What is the role of pH in determining protein properties?
What is the role of pH in determining protein properties?
What are the general functions of proteins in living systems?
What are the general functions of proteins in living systems?
What are the three dynamic functions of proteins?
What are the three dynamic functions of proteins?
Give an example of a protein involved in enzymatic catalysis.
Give an example of a protein involved in enzymatic catalysis.
Give an example of a protein involved in transport.
Give an example of a protein involved in transport.
Give an example of a protein involved in protective role.
Give an example of a protein involved in protective role.
What are the structural functions of proteins?
What are the structural functions of proteins?
Proteins are the most versatile macromolecules in living systems and serve crucial functions in all biological processes.
Proteins are the most versatile macromolecules in living systems and serve crucial functions in all biological processes.
Almost all biological reactions are enzyme catalyzed.
Almost all biological reactions are enzyme catalyzed.
Haemoglobin and myoglobin transport oxygen in blood and in muscle, respectively.
Haemoglobin and myoglobin transport oxygen in blood and in muscle, respectively.
Fibrin is formed where required to stop the loss of blood on injury to the vascular system.
Fibrin is formed where required to stop the loss of blood on injury to the vascular system.
Many hormones are proteins, including insulin, thyrotropin, and somatotropin.
Many hormones are proteins, including insulin, thyrotropin, and somatotropin.
Myosin and actin function in muscle contraction.
Myosin and actin function in muscle contraction.
Histone proteins are closely associated with DNA and control gene expression.
Histone proteins are closely associated with DNA and control gene expression.
Collagen and elastin form the matrix for bone, ligaments, connective tissue, and skin.
Collagen and elastin form the matrix for bone, ligaments, connective tissue, and skin.
Proteins provide structural strength and elasticity to organs.
Proteins provide structural strength and elasticity to organs.
Keratin is the primary component of human hair, nails, skin, and tooth enamel.
Keratin is the primary component of human hair, nails, skin, and tooth enamel.
Study Notes
Classification and Properties of Peptides and Proteins
- Ornithine and citrulline are metabolites involved in the biosynthesis of arginine and the urea cycle.
- Amino acids are classified into nonpolar, aliphatic; aromatic; polar, uncharged; and charged categories.
- Peptide bonds covalently join amino acids in proteins, and can be hydrolyzed non-enzymatically under certain conditions.
- A polypeptide is an unbranched chain of amino acids linked through peptide bonds, and its naming convention involves changing the suffixes of amino acid residues.
- The peptide bond has a partial double-bond character, conferring rigidity and preventing free rotation.
- The peptide bond is generally in the trans configuration.
- The peptide bond is uncharged, and the charged groups present in polypeptides are the N-terminal α-amino group, C-terminal α-carboxyl group, and ionized groups in the side chains of amino acids.
- Small peptides may contain D-amino acids or be linked by bonds other than the standard peptide bond.
- Glutathione is a tripeptide with biochemical importance, acting as a coenzyme and undergoing oxidation under certain conditions.
- Proteins are classified based on their composition, molecular weight, molecular shape, function, source, and physicochemical properties.
- Proteins can be classified as simple (containing only amino acids) or conjugated (containing additional substances).
- Albumins are a type of simple protein that are water soluble and precipitated with full saturation in ammonium sulfate.
Classification and Properties of Peptides and Proteins
- Ornithine and citrulline are metabolites involved in the biosynthesis of arginine and the urea cycle.
- Amino acids are classified into nonpolar, aliphatic; aromatic; polar, uncharged; and charged categories.
- Peptide bonds covalently join amino acids in proteins, and can be hydrolyzed non-enzymatically under certain conditions.
- A polypeptide is an unbranched chain of amino acids linked through peptide bonds, and its naming convention involves changing the suffixes of amino acid residues.
- The peptide bond has a partial double-bond character, conferring rigidity and preventing free rotation.
- The peptide bond is generally in the trans configuration.
- The peptide bond is uncharged, and the charged groups present in polypeptides are the N-terminal α-amino group, C-terminal α-carboxyl group, and ionized groups in the side chains of amino acids.
- Small peptides may contain D-amino acids or be linked by bonds other than the standard peptide bond.
- Glutathione is a tripeptide with biochemical importance, acting as a coenzyme and undergoing oxidation under certain conditions.
- Proteins are classified based on their composition, molecular weight, molecular shape, function, source, and physicochemical properties.
- Proteins can be classified as simple (containing only amino acids) or conjugated (containing additional substances).
- Albumins are a type of simple protein that are water soluble and precipitated with full saturation in ammonium sulfate.
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Description
Test your knowledge of amino acid structure and physicochemical properties with this quiz! Learn about the building blocks of peptides and proteins, the composition of α-amino acids, and the unique R group. Challenge yourself and expand your understanding of amino acids.
