Protein Folding - Biochemistry
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Which of the following describes the primary structure of a protein?
Which of the following describes the primary structure of a protein?
The primary structure of a protein is defined by the sequence of amino acid residues. It is this sequence that lays the foundation for all other higher levels of structures in a protein. Secondary structure is defined by the hydrogen bonding between the carboxyl and amino backbone of the amino acids. Tertiary is defined by amino acid side chain interactions. Finally, quaternary structure is defined by the assembly of subunits of a protein into the overall larger protein structure.
The primary structure of a protein is defined by the sequence of amino acid residues. It is this sequence that lays the foundation for all other higher levels of structures in a protein. Secondary structure is defined by the hydrogen bonding between the carboxyl and amino backbone of the amino acids. Tertiary is defined by amino acid side chain interactions. Finally, quaternary structure is defined by the assembly of subunits of a protein into the overall larger protein structure.
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What is the primary structure of a protein?
What is the primary structure of a protein?
The primary structure is only composed of the sequence of amino acids in a protein. The secondary structure is the alpha or beta folding that occurs due to amino acid interaction. The tertiary structure is the three dimensional folding that occurs within a protein. Finally, quaternary structure occurs when a protein has two or more polypeptide sub-units. A perfect example of quaternary structure is found in hemoglobin.
The primary structure is only composed of the sequence of amino acids in a protein. The secondary structure is the alpha or beta folding that occurs due to amino acid interaction. The tertiary structure is the three dimensional folding that occurs within a protein. Finally, quaternary structure occurs when a protein has two or more polypeptide sub-units. A perfect example of quaternary structure is found in hemoglobin.
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The formation of a peptide bond is an example of what type of reaction?
The formation of a peptide bond is an example of what type of reaction?
The formation of a peptide bond is an example of a condensation reaction. This is because, when two amino acids come together, a water molecule is let go.
The formation of a peptide bond is an example of a condensation reaction. This is because, when two amino acids come together, a water molecule is let go.
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Sickle cell anemia is caused by a point mutation in hemoglobin, where a glutamate residue is changed to a valine. Based on this mutation mechanism, what level of protein structure is affected by sickle cell anemia?
Sickle cell anemia is caused by a point mutation in hemoglobin, where a glutamate residue is changed to a valine. Based on this mutation mechanism, what level of protein structure is affected by sickle cell anemia?
Because an amino acid has been altered in sickle cell anemia, we can say that the amino acid sequence for hemoglobin has been changed. The amino acid sequence is defined as the primary structure for a protein, so that is the level that has been altered. It should be noted that the subsequent levels of protein structure would be altered as well, but the manipulation of the amino acid sequence is a changing of the primary structure first.
Because an amino acid has been altered in sickle cell anemia, we can say that the amino acid sequence for hemoglobin has been changed. The amino acid sequence is defined as the primary structure for a protein, so that is the level that has been altered. It should be noted that the subsequent levels of protein structure would be altered as well, but the manipulation of the amino acid sequence is a changing of the primary structure first.
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Which of these macromolecules has quarternary structure?
Which of these macromolecules has quarternary structure?
Hemoglobin is the only available example of a macromolecule composed of multiple subunits. Hemoglobin has frou subunits, each capable of binding and transporting one molecule of oxygen in the blood.
Chymotrypsin and myogblobin are both simple proteins, each consisting of a single polypeptide. These proteins do not have multiple subunits; thus their highest level of structure is tertiary (three-dimensional). Lactose and sucrose are disaccharides, each composed of two carbohydrate monomers (monosaccharides).
Hemoglobin is the only available example of a macromolecule composed of multiple subunits. Hemoglobin has frou subunits, each capable of binding and transporting one molecule of oxygen in the blood.
Chymotrypsin and myogblobin are both simple proteins, each consisting of a single polypeptide. These proteins do not have multiple subunits; thus their highest level of structure is tertiary (three-dimensional). Lactose and sucrose are disaccharides, each composed of two carbohydrate monomers (monosaccharides).
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Hemoglobin is a protein that possesses more than one polypeptide subunit, therefore it has a __________ structure.
Hemoglobin is a protein that possesses more than one polypeptide subunit, therefore it has a __________ structure.
Hemoglobin is a tetramer that possesses a quaternary structure containing multiple folded polypeptide structures (tertiary structures). A tertiary protein will commonly contain a single polypeptide chain with one or more secondary structures.
Hemoglobin is a tetramer that possesses a quaternary structure containing multiple folded polypeptide structures (tertiary structures). A tertiary protein will commonly contain a single polypeptide chain with one or more secondary structures.
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Which of the following is true about quaternary structure?
Which of the following is true about quaternary structure?
A protein with multiple identical subunits does indeed have a quaternary structure; in these cases, dimers and tetramers are common. The main forces holding together oligomeric subunits are weak, non-covalent interactions, specifically, hydrophobic ones, as well as electrostatic forces. Subunits do not necessarily form separate domains within a protein; in a potassium channel protein, for example, there are identical subunits which come together to form the single channel. Proteins’ 3D-structures do indeed sometimes change when ligands bind; this change help regulate the proteins’ biological activity.
A protein with multiple identical subunits does indeed have a quaternary structure; in these cases, dimers and tetramers are common. The main forces holding together oligomeric subunits are weak, non-covalent interactions, specifically, hydrophobic ones, as well as electrostatic forces. Subunits do not necessarily form separate domains within a protein; in a potassium channel protein, for example, there are identical subunits which come together to form the single channel. Proteins’ 3D-structures do indeed sometimes change when ligands bind; this change help regulate the proteins’ biological activity.
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Which of the following proteins do not have quaternary structure?
Which of the following proteins do not have quaternary structure?
Quaternary structure of a protein involves the assembly of subunits. Hemoglobin, p53 and DNA polymerase are all composed of subunits, while myoglobin is a functional single sequence. Since myoglobin does not have multiple subunits, it does not have quaternary structure.
Quaternary structure of a protein involves the assembly of subunits. Hemoglobin, p53 and DNA polymerase are all composed of subunits, while myoglobin is a functional single sequence. Since myoglobin does not have multiple subunits, it does not have quaternary structure.
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Which of the following best describes the quaternary structure of a protein?
Which of the following best describes the quaternary structure of a protein?
Quaternary structure describes how polypeptide chains fit together to form a complete protein. Quaternary protein structure is held together by hydrophobic interactions, and disulfide bridges. The sequence of amino acids is known as primary structure; helices, sheets, and similar features are part of the secondary structure; and the 3-D organization is tertiary structure. "The four parts of a protein's amino acid sequence" does not refer to anything in particular.
Quaternary structure describes how polypeptide chains fit together to form a complete protein. Quaternary protein structure is held together by hydrophobic interactions, and disulfide bridges. The sequence of amino acids is known as primary structure; helices, sheets, and similar features are part of the secondary structure; and the 3-D organization is tertiary structure. "The four parts of a protein's amino acid sequence" does not refer to anything in particular.
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Which of the following best explains a quaternary structure of a protein?
Which of the following best explains a quaternary structure of a protein?
Primary structure: linear sequence of amino acids
Secondary structure: hydrogen bonds, alpha-helices and beta-pleated sheets
Tertiary structure: disulfide bonds, single polypeptide chain
Myoglobin is a monomer, and is made of a single polypeptide chain. Thus, its highest level of protein structure is tertiary. While collagen does contain different polypeptide chains, it is an example of a protein with quaternary structure, not an explanation of what this means.
Primary structure: linear sequence of amino acids
Secondary structure: hydrogen bonds, alpha-helices and beta-pleated sheets
Tertiary structure: disulfide bonds, single polypeptide chain
Myoglobin is a monomer, and is made of a single polypeptide chain. Thus, its highest level of protein structure is tertiary. While collagen does contain different polypeptide chains, it is an example of a protein with quaternary structure, not an explanation of what this means.
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What is the primary driver of protein folding on a macro level?
What is the primary driver of protein folding on a macro level?
While covalent bonds create the primary structure of a protein, and hydrogen bonding and Van der Waals forces have a large impact on the secondary structure of a protein, they are not the main contributors to overall folding of a protein. This has more to do with solvation costs, hydrophobicity, and entropy. The hydrophobicity and hydrophobic portions of the protein must fold to minimize entropic costs.
While covalent bonds create the primary structure of a protein, and hydrogen bonding and Van der Waals forces have a large impact on the secondary structure of a protein, they are not the main contributors to overall folding of a protein. This has more to do with solvation costs, hydrophobicity, and entropy. The hydrophobicity and hydrophobic portions of the protein must fold to minimize entropic costs.
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Which of the following statements is true about proteins with quaternary structures?
I. Proteins are composed of multiple polypeptide chains.
II. Proteins are composed of subunits that interact through weak forces (noncovalent) only.
III. Sub-units may work cooperatively,one sub-unit binding to a molecule increases the affinity of the other sub-units for the same ligand.
IV. Hemoglobin is a protein displaying a quaternary structure composed of 4 sub-units.
Which of the following statements is true about proteins with quaternary structures?
I. Proteins are composed of multiple polypeptide chains.
II. Proteins are composed of subunits that interact through weak forces (noncovalent) only.
III. Sub-units may work cooperatively,one sub-unit binding to a molecule increases the affinity of the other sub-units for the same ligand.
IV. Hemoglobin is a protein displaying a quaternary structure composed of 4 sub-units.
Hemoglobin is a classic example of protein with a quaternary structure. The binding of oxygen to one sub unit increases the affinity of the other sub units for oxygen (cooperativity). Adult hemoglobin is made of two alpha globin and two beta globin polypeptides. Protein quaternary structure may involve both noncovalent and covalent forces.
Hemoglobin is a classic example of protein with a quaternary structure. The binding of oxygen to one sub unit increases the affinity of the other sub units for oxygen (cooperativity). Adult hemoglobin is made of two alpha globin and two beta globin polypeptides. Protein quaternary structure may involve both noncovalent and covalent forces.
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What type of bonds are the "backbone" of secondary protein structure?
What type of bonds are the "backbone" of secondary protein structure?
Hydrogen bonds stabilize interactions among the amide and carboxyl groups in the main chain of the polypeptide. These interactions may induce the formation of alpha-helices and/or beta-pleated sheets.
Hydrogen bonds stabilize interactions among the amide and carboxyl groups in the main chain of the polypeptide. These interactions may induce the formation of alpha-helices and/or beta-pleated sheets.
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The stabilization of secondary structure in polypeptides is conferred by which of the following?
The stabilization of secondary structure in polypeptides is conferred by which of the following?
Alpha helices and beta sheet, the dominant secondary structural motifs in polypeptides are formed by hydrogen bonds between the carbonyl and amino groups of the amino acid backbone.
Alpha helices and beta sheet, the dominant secondary structural motifs in polypeptides are formed by hydrogen bonds between the carbonyl and amino groups of the amino acid backbone.
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Why are antiparallel beta sheets more stable than parallel beta sheets?
Why are antiparallel beta sheets more stable than parallel beta sheets?
In an antiparallel beta sheet, the hydrogen bonding angle is 180 degrees and optimal; this is the most stable angle. In parallel sheets, it is a less stable 150 degrees. Whether a sheet is parallel or antiparallel does not tell us anything about what amino acids it is composed of, so each of the other answers is incorrect.
In an antiparallel beta sheet, the hydrogen bonding angle is 180 degrees and optimal; this is the most stable angle. In parallel sheets, it is a less stable 150 degrees. Whether a sheet is parallel or antiparallel does not tell us anything about what amino acids it is composed of, so each of the other answers is incorrect.
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In a sequence of amino acids within an alpha helix, between which amino acids in the sequence does hydrogen bonding occur (i.e. every how many amino acids)?
In a sequence of amino acids within an alpha helix, between which amino acids in the sequence does hydrogen bonding occur (i.e. every how many amino acids)?
In an alpha helix, hydrogen bonding occurs every four amino acids, starting from the 1st binding to the 4th in the sequence; the 2nd amino acid binds to the 6th, the 3rd to the 7th, and so on.
In an alpha helix, hydrogen bonding occurs every four amino acids, starting from the 1st binding to the 4th in the sequence; the 2nd amino acid binds to the 6th, the 3rd to the 7th, and so on.
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What is the only level of protein structure that does not involve covalent bonding?
What is the only level of protein structure that does not involve covalent bonding?
Covalent bonding is when two nonmetals share electrons in order to form a bond. This type of bonding can be observed in the primary (peptide bonds), tertiary (disulfide bonds), and quaternary (disulfide bonds) levels of protein structure. The secondary structure of proteins only uses hydrogen bonding as the folding force.
Covalent bonding is when two nonmetals share electrons in order to form a bond. This type of bonding can be observed in the primary (peptide bonds), tertiary (disulfide bonds), and quaternary (disulfide bonds) levels of protein structure. The secondary structure of proteins only uses hydrogen bonding as the folding force.
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How many amino acids are per turn in an alpha helix secondary structure?
How many amino acids are per turn in an alpha helix secondary structure?
Polypeptide chains in proteins fold to attain a more compact secondary structure. The two forms of secondary structures are alpha helices and beta sheets. Amino acids that are separated by three or four residues in a polypeptide chain within a secondary alpha helix structure are spatially close and can form hydrogen bonds.
Polypeptide chains in proteins fold to attain a more compact secondary structure. The two forms of secondary structures are alpha helices and beta sheets. Amino acids that are separated by three or four residues in a polypeptide chain within a secondary alpha helix structure are spatially close and can form hydrogen bonds.
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The alpha helix is a type of secondary protein conformation. Which of the following amino acids can interfere the most with the formation of an alpha helix?
The alpha helix is a type of secondary protein conformation. Which of the following amino acids can interfere the most with the formation of an alpha helix?
Secondary structures in proteins consist of alpha helices and beta sheets. Proline has an additional amino group that interferes with the formation of an alpha helix. Amino acids such as lysine and arginine can form ionic bonds due to their charges. Other amino acids, like isoleucine, tryptophan, or valine disrupt the helix due to big side chains. However, amongst the amino acid mentioned in the answers, proline has the most disruptive effect.
Secondary structures in proteins consist of alpha helices and beta sheets. Proline has an additional amino group that interferes with the formation of an alpha helix. Amino acids such as lysine and arginine can form ionic bonds due to their charges. Other amino acids, like isoleucine, tryptophan, or valine disrupt the helix due to big side chains. However, amongst the amino acid mentioned in the answers, proline has the most disruptive effect.
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Which of the following are true of beta bends in protein structures?
I. Beta bends are secondary protein structures.
II. Beta bends consist of sequences of four amino acids.
III. In beta bends amino acids proline and glycine are common.
IV. Hydrogen and ionic bonds stabilize beta bends.
Which of the following are true of beta bends in protein structures?
I. Beta bends are secondary protein structures.
II. Beta bends consist of sequences of four amino acids.
III. In beta bends amino acids proline and glycine are common.
IV. Hydrogen and ionic bonds stabilize beta bends.
Beta bends are part of secondary protein structures. They serve as a link between alpha helices and beta sheets. Beta bends are composed of proline and glycine, amino acids that usually are not found in alpha helices.
Beta bends are part of secondary protein structures. They serve as a link between alpha helices and beta sheets. Beta bends are composed of proline and glycine, amino acids that usually are not found in alpha helices.
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