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Questions and Answers
What characteristic prevents free rotation around the bond between the carbonyl carbon and the nitrogen of the peptide bond?
What characteristic prevents free rotation around the bond between the carbonyl carbon and the nitrogen of the peptide bond?
Which condition is required to non-enzymatically hydrolyze peptide bonds?
Which condition is required to non-enzymatically hydrolyze peptide bonds?
What term is used to describe each component amino acid in a polypeptide?
What term is used to describe each component amino acid in a polypeptide?
What stabilizes an α-helix structure by extensive hydrogen bonding between the peptide-bond carbonyl oxygens and amide hydrogens?
What stabilizes an α-helix structure by extensive hydrogen bonding between the peptide-bond carbonyl oxygens and amide hydrogens?
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What type of secondary structure forms when two or more separate polypeptide chains are arranged in parallel or antiparallel to each other?
What type of secondary structure forms when two or more separate polypeptide chains are arranged in parallel or antiparallel to each other?
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What is the name of the linear sequence of linked amino acids in a protein?
What is the name of the linear sequence of linked amino acids in a protein?
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Why is understanding the primary structure of proteins important?
Why is understanding the primary structure of proteins important?
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What type of bond joins amino acids together in proteins?
What type of bond joins amino acids together in proteins?
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What results from the linkage of many amino acids through peptide bonds?
What results from the linkage of many amino acids through peptide bonds?
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What type of bond joins amino acids together in proteins?
What type of bond joins amino acids together in proteins?
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What is the name of the level of protein structure that involves the sequence of amino acids in a protein?
What is the name of the level of protein structure that involves the sequence of amino acids in a protein?
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What is the convention for naming the ends of a peptide chain?
What is the convention for naming the ends of a peptide chain?
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What condition results in proteins with abnormal amino acid sequences, causing improper folding and loss of normal function?
What condition results in proteins with abnormal amino acid sequences, causing improper folding and loss of normal function?
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What characteristic prevents free rotation around the bond between the carbonyl carbon and the nitrogen of the peptide bond?
What characteristic prevents free rotation around the bond between the carbonyl carbon and the nitrogen of the peptide bond?
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What is the convention for writing the free amino end (N-terminal) and the free carboxyl end (C-terminal) of a peptide chain?
What is the convention for writing the free amino end (N-terminal) and the free carboxyl end (C-terminal) of a peptide chain?
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Which type of structure forms when two or more separate polypeptide chains are arranged in parallel or antiparallel to each other?
Which type of structure forms when two or more separate polypeptide chains are arranged in parallel or antiparallel to each other?
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What term is used to describe the portion of the amino acid remaining after the atoms of water are lost in the formation of the peptide bond?
What term is used to describe the portion of the amino acid remaining after the atoms of water are lost in the formation of the peptide bond?
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What is required to non-enzymatically hydrolyze peptide bonds?
What is required to non-enzymatically hydrolyze peptide bonds?
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What type of bond has a partial double-bond character and is shorter than a single bond?
What type of bond has a partial double-bond character and is shorter than a single bond?
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Which structure is stabilized by extensive hydrogen bonding between the peptide-bond carbonyl oxygens and amide hydrogens?
Which structure is stabilized by extensive hydrogen bonding between the peptide-bond carbonyl oxygens and amide hydrogens?
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What is the term for the spiral structure consisting of a tightly packed, coiled polypeptide backbone core, with the side chains of the component amino acids extending outward?
What is the term for the spiral structure consisting of a tightly packed, coiled polypeptide backbone core, with the side chains of the component amino acids extending outward?
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How many amino acids are contained in each turn of an α-helix?
How many amino acids are contained in each turn of an α-helix?
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What type of secondary structure is formed by two or more separate polypeptide chains that are arranged in parallel or antiparallel to each other?
What type of secondary structure is formed by two or more separate polypeptide chains that are arranged in parallel or antiparallel to each other?
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What type of sheet appears 'pleated' due to the almost fully extended segments of polypeptide chains involved in hydrogen bonding?
What type of sheet appears 'pleated' due to the almost fully extended segments of polypeptide chains involved in hydrogen bonding?
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What characteristic prevents free rotation around the bond between the α-carbons in the polypeptide chain?
What characteristic prevents free rotation around the bond between the α-carbons in the polypeptide chain?
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What type of bond helps reverse the direction of a polypeptide chain, aiding in the formation of a compact, globular structure?
What type of bond helps reverse the direction of a polypeptide chain, aiding in the formation of a compact, globular structure?
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Study Notes
Peptide Bonds and Structure
- Partial Double-Bond Character: The peptide bond exhibits a partial double-bond character due to resonance, preventing free rotation around the bond between the carbonyl carbon and nitrogen.
- Hydrolysis Conditions: Non-enzymatic hydrolysis of peptide bonds requires strong acids or bases and elevated temperatures.
- Amino Acid Component: Each amino acid in a polypeptide is referred to as a residue.
- Stabilization of Alpha Helix: The α-helix structure is stabilized by extensive hydrogen bonding between the carbonyl oxygens of one peptide bond and the amide hydrogens of another, four residues away.
- Secondary Structure Formation: Secondary structures, such as β-sheets, form when two or more polypeptide chains arrange in parallel or antiparallel orientations.
- Primary Structure Definition: The linear sequence of linked amino acids in a protein is known as its primary structure.
- Importance of Primary Structure: Understanding primary structure is essential as it dictates protein folding and function.
- Peptide Bond Formation: Amino acids are joined together in proteins through peptide bonds, formed by a condensation reaction between the carboxyl and amino groups.
- Polypeptide Formation: The linkage of numerous amino acids via peptide bonds results in the formation of polypeptides or proteins.
- Peptide Chain Naming Convention: The free amino end is termed the N-terminal, while the free carboxyl end is the C-terminal.
- Abnormal Sequences and Folding: Conditions causing abnormal amino acid sequences lead to improper folding, resulting in loss of function.
- Hydration of Peptide Bonds: Non-enzymatic hydrolysis of peptide bonds demands specific environmental conditions like high heat and strong solvents.
- Alpha Helix Characteristics: Each turn of an α-helix typically consists of 3.6 amino acids.
- Beta Sheet Structure: The pleated sheet structure arises from nearly fully extended polypeptide segments that engage in hydrogen bonding.
- Rotation Limitation: Free rotation around the bonds connecting α-carbons in the polypeptide chain is limited due to steric hindrance and the structure of neighboring groups.
- Reverse Polypeptide Direction: Hydrogen bonds also aid in reversing the direction of polypeptide chains, contributing to the compactness of globular structures.
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Description
Test your knowledge about protein structures with a focus on the primary, secondary, tertiary, and quaternary levels of organization. Understand how amino acids are joined together by peptide bonds to form unique three-dimensional shapes.
