Skip to main content
Back

Isoelectric Focusing quiz

Control buttons has been changed to "navigation" mode.
1/15
  • What does IEF stand for in biochemistry?
    IEF stands for isoelectric focusing, a technique used to separate proteins based on their isoelectric points.
  • What is the isoelectric point (pI) of a protein?
    The isoelectric point (pI) is the specific pH at which a protein has a net charge of zero.
  • How does isoelectric focusing separate proteins?
    Isoelectric focusing separates proteins based on their isoelectric points by using an electric field and a stable pH gradient.
  • What is established in the gel during isoelectric focusing?
    A stable, immobile pH gradient is established in the gel, decreasing linearly from high pH at the top to low pH at the bottom.
  • Why do proteins stop migrating in the gel during IEF?
    Proteins stop migrating when they reach the region where the pH equals their pI, resulting in a net charge of zero.
  • What happens to the charge of proteins as they move through the gel?
    Proteins change their charge as they encounter different pH regions in the gel, due to changes in ionization of their ionizable groups.
  • Why is the pH gradient described as 'immobile' in IEF?
    The pH gradient is called immobile because the pH at each region of the gel remains constant throughout the process.
  • What determines the position of a protein band in an IEF gel?
    The position of a protein band corresponds to the pH region where the protein's pI matches the gel's pH.
  • What is the relationship between pH and pI at the top of the IEF gel?
    At the top of the IEF gel, the pH is high, so proteins with high pI values stop migrating there.
  • What is the relationship between pH and pI at the bottom of the IEF gel?
    At the bottom of the IEF gel, the pH is low, so proteins with low pI values stop migrating there.
  • What causes proteins to stop moving in an electric field during IEF?
    Proteins stop moving when they have a neutral net charge, which occurs when the pH equals their pI.
  • How can the isoelectric point of a protein be determined using IEF?
    The isoelectric point can be determined by identifying the pH region in the gel where the protein band stops.
  • What is the main purpose of isoelectric focusing?
    The main purpose of isoelectric focusing is to separate proteins based on their isoelectric points.
  • What happens to the ionization state of a protein as it moves through the pH gradient?
    The ionization state of a protein changes as it moves through different pH regions, altering its net charge.
  • Why do proteins with a net charge of zero not migrate in an electric field?
    Proteins with a net charge of zero do not migrate because they are not attracted to either electrode in the electric field.