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 (D)</p> Signup and view all the answers

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

<p>β-sheet (D)</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 (D)</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 (C)</p> Signup and view all the answers

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

<p>Globular proteins (B)</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 (A)</p> Signup and view all the answers

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

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

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

<p><strong>Parkinson's Disease</strong> (C)</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> (D)</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> (A)</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 (C)</p> Signup and view all the answers

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

<p>Proline (C)</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 (D)</p> Signup and view all the answers

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

<p>5.4Ã… (A)</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 (C)</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 (D)</p> Signup and view all the answers

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

<p>Inhibits Hb from binding to oxygen (B)</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 (D)</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 (A)</p> Signup and view all the answers

How is protein structure typically determined?

<p>Through X-ray diffraction of protein crystals (D)</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 (A)</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 (A)</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 (D)</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 (C)</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 (D)</p> Signup and view all the answers

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

<p>5.4 Ã… (A)</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 (A)</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 (A)</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 (B)</p> Signup and view all the answers

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

<p>Extended 'flat' sheet structure (B)</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 (A)</p> Signup and view all the answers

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

<p>Hydrogen bonds (D)</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 (D)</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 (C)</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 (A)</p> Signup and view all the answers

What percentage of human proteins is post-transcriptionally modified?

<p>60% (A)</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 (A)</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 (D)</p> Signup and view all the answers

What causes Parkinson's disease according to the text?

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

Which factor is NOT a common cause of protein denaturation?

<p>Increasing hydrogen bonding with urea/guanidine (B)</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 (A)</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 (B)</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 (D)</p> Signup and view all the answers

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

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

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