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Alpha Helix quiz #1

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  • What is the alpha helix, and how is its structure stabilized?
    The alpha helix is a secondary protein structure with a coiled, spiral conformation. Its structure is stabilized by nearly parallel hydrogen bonds formed along the protein backbone, not involving the R groups.
  • How do the R groups of amino acids orient themselves in an alpha helix, and why is this orientation important?
    In an alpha helix, the R groups of amino acids point radially outward from the helix axis. This orientation minimizes steric hindrance, enhancing the stability of the helix.
  • What is the difference between right-handed and left-handed alpha helices, and which is more common in nature?
    Right-handed alpha helices have a clockwise twist and are more stable and common in nature, while left-handed alpha helices have a counterclockwise twist and are rare.
  • How can the Ramachandran plot be used to distinguish between right-handed and left-handed alpha helices?
    The Ramachandran plot shows right-handed alpha helices in the bottom left quadrant and left-handed alpha helices in the upper right quadrant, helping to distinguish between these two forms.
  • What type of secondary protein structure is the alpha helix, and what stabilizes its structure?
    The alpha helix is a coiled, spiral secondary protein structure stabilized by nearly parallel hydrogen bonds along the backbone, not involving the R groups.
  • How are hydrogen bonds oriented in an alpha helix relative to its axis?
    The hydrogen bonds in an alpha helix are nearly parallel to the axis of the helix.
  • How do the R groups of amino acids orient themselves in an alpha helix, and why is this important?
    The R groups point radially outward from the helix axis to minimize steric hindrance, which enhances the stability of the helix.
  • What is the difference between right-handed and left-handed alpha helices, and which is more common in nature?
    Right-handed alpha helices have a clockwise twist and are more stable and common in nature, while left-handed alpha helices have a counterclockwise twist and are rare.
  • How can you use your hands to distinguish between right-handed and left-handed alpha helices?
    If you point your thumb up the helix axis, the direction your fingers curl shows the helix's twist: right hand for right-handed (clockwise) and left hand for left-handed (counterclockwise) helices.
  • How does the Ramachandran plot help distinguish between right-handed and left-handed alpha helices?
    The Ramachandran plot shows right-handed alpha helices in the bottom left quadrant and left-handed alpha helices in the upper right quadrant.
  • What feature characterizes the secondary structure of a protein known as the alpha helix?
    The alpha helix is characterized by a coiled, spiral conformation of the protein backbone stabilized by nearly parallel hydrogen bonds along the backbone, with R groups pointing radially outward from the helix axis.