Proteins and Structural Motifs Quiz
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Questions and Answers

What type of protein structure is characterized by local conformations maintained by extensive hydrogen bonding involving the peptide bond components?

  • Quaternary structure
  • Tertiary structure
  • Secondary structure (correct)
  • Primary structure
  • Which type of secondary structure in proteins is described as 'helical and coiled'?

  • β-sheet
  • α-helix (correct)
  • Random coil
  • Turn
  • Which bond in the protein structure allows free rotation between the alpha-carbon and amino nitrogen in a residue?

  • Disulfide bond
  • Phi bond (correct)
  • Peptide bond
  • Glycosidic bond
  • In an α-helix, how are the hydrogen bonds oriented with respect to the helix axis?

    <p>Parallel</p> Signup and view all the answers

    Which type of secondary protein structure forms 'extended flat sheets'?

    <p>β-sheet</p> Signup and view all the answers

    What pattern of hydrogen bonds helps form secondary structures like α-helices and β-strands?

    <p>Hydrogen bonds</p> Signup and view all the answers

    What stabilizes the tertiary (3°) structure of a protein?

    <p>Interactions of amino acid side chains in non-neighboring regions</p> Signup and view all the answers

    What type of proteins often combine alpha-helix and beta-sheets in their structure?

    <p>Globular proteins</p> Signup and view all the answers

    Which protein structure is characterized by interactions of amino acid side chains in non-neighboring regions?

    <p>Tertiary structure</p> Signup and view all the answers

    What is the main cause of denaturation known as protein unfolding?

    <p>Changes in side chain electrostatics</p> Signup and view all the answers

    Which health condition is mentioned as an example associated with denaturation?

    <p><strong>Parkinson's Disease</strong></p> Signup and view all the answers

    What is the term used to describe the effect where non-polar species in water reduce entropy?

    <p><strong>Hydrophobic Effect</strong></p> Signup and view all the answers

    Which type of proteins have hydrophobic residues inside and play a role in disrupting protein folding?

    <p><strong>Membrane proteins</strong></p> Signup and view all the answers

    What type of bond is formed between the C=O of amino acid #1 and N-H of amino acid #5 in an alpha helix structure?

    <p>Hydrogen bond</p> Signup and view all the answers

    What disrupts an alpha helix structure by creating a bend or 'kink'?

    <p>Proline</p> Signup and view all the answers

    How many amino acids typically make up one turn of an alpha helix structure?

    <p>3.6 amino acids</p> Signup and view all the answers

    What is the distance of one turn repeat in an alpha helix structure?

    <p>5.4Å</p> Signup and view all the answers

    In a beta-pleated sheet, what type of bonds form between the backbones of adjacent polypeptide chains?

    <p>Hydrogen bonds</p> Signup and view all the answers

    Which amino acid is commonly found in reverse turns of protein structures due to steric reasons?

    <p>Glycine</p> Signup and view all the answers

    What is the effect of 2,3-BPG on hemoglobin?

    <p>Inhibits Hb from binding to oxygen</p> Signup and view all the answers

    How does the presence of 2,3-BPG affect the affinity of hemoglobin for oxygen?

    <p>Decreases the affinity of hemoglobin for oxygen</p> Signup and view all the answers

    What is the role of 2,3-BPG in red blood cells?

    <p>It binds to hemoglobin at a 1:1 molar ratio</p> Signup and view all the answers

    How is protein structure typically determined?

    <p>Through X-ray diffraction of protein crystals</p> Signup and view all the answers

    Which factor markedly decreases hemoglobin's affinity for oxygen?

    <p>Increasing the binding of 2,3-BPG to Hb</p> Signup and view all the answers

    What disrupts an alpha helix structure by creating a bend or 'kink'?

    <p>Steric crowding from bulky side chains like Val, Ile, Thr</p> Signup and view all the answers

    What type of secondary structure involves polypeptide chains lying adjacent to one another in a sheet-like structure?

    <p>Beta-pleated sheet</p> Signup and view all the answers

    What factor contributes to disrupting an alpha helix structure due to restricted rotation and lack of N-H for hydrogen bonding?

    <p>Proline's cyclic structure and lack of N-H for hydrogen bonding</p> Signup and view all the answers

    In a beta-pleated sheet, what type of bonds form between the backbones of adjacent polypeptide chains?

    <p>Hydrogen bonds</p> Signup and view all the answers

    What is the distance of one turn repeat in an alpha helix structure?

    <p>5.4 Å</p> Signup and view all the answers

    Which amino acid is commonly found in reverse turns of protein structures due to steric reasons?

    <p>Glycine</p> Signup and view all the answers

    What is the major type of secondary structure in proteins formed by a regular pattern of hydrogen bonds between amide N-H and C=O groups of amino acids near each other in the primary sequence?

    <p>α-helix</p> Signup and view all the answers

    Which bond in protein structure allows free rotation between the α-carbon and amino nitrogen in a residue?

    <p>Peptide bond</p> Signup and view all the answers

    What is the characteristic feature of β-sheets in protein secondary structure?

    <p>Extended 'flat' sheet structure</p> Signup and view all the answers

    In an α-helix, how are the hydrogen bonds oriented with respect to the helix axis?

    <p>Parallel</p> Signup and view all the answers

    What type of bonds hold together α-helices both intrachain and interchain?

    <p>Hydrogen bonds</p> Signup and view all the answers

    Which component of proteins plays a crucial role in maintaining local conformation through extensive hydrogen bonding involving peptide bond components?

    <p>Amide H of the peptide backbone</p> Signup and view all the answers

    What is the primary (1°) structure of a protein referring to?

    <p>The sequence of amino acids in a polypeptide chain</p> Signup and view all the answers

    In protein folding, which force is considered a stabilizing force due to its interactions with non-polar residues?

    <p>Hydrophobic effect</p> Signup and view all the answers

    What percentage of human proteins is post-transcriptionally modified?

    <p>60%</p> Signup and view all the answers

    Which level of protein structure involves the way the polypeptide chain folds up in three-dimensional space?

    <p>Tertiary structure</p> Signup and view all the answers

    What is the primary structural difference between Hemoglobin and Hemoglobin2ia mentioned in the text?

    <p>Destabilizing force in Hemoglobin2ia</p> Signup and view all the answers

    What causes Parkinson's disease according to the text?

    <p>Misfolding of proteins in bacteria</p> Signup and view all the answers

    What is the main goal of the CASP challenge?

    <p>To improve computational methods for predicting protein structures</p> Signup and view all the answers

    Which factor is NOT a common cause of protein denaturation?

    <p>Increasing hydrogen bonding with urea/guanidine</p> Signup and view all the answers

    What can contribute to diseases like Alzheimer's and Diabetes type 2?

    <p>Protein aggregation linked to neurodegenerative diseases</p> Signup and view all the answers

    Which process can proteins undergo if denaturation is not too severe?

    <p>Renaturation back to the native structure</p> Signup and view all the answers

    What is a significant effect of non-polar species on water in terms of protein folding?

    <p>Decrease in entropy as water organizes around non-polar species</p> Signup and view all the answers

    Which type of proteins are often linked to disrupting protein folding?

    <p>Proteins with hydrophobic residues inside</p> Signup and view all the answers

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