Electrophoresis Basics
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Questions and Answers

What determines the amount of time needed for electrophoresis?

  • Number of bands observed
  • Color intensity of the dye
  • Length of the gel, voltage used, and sizes of the molecules in the sample (correct)
  • Presence of DNA ladders with tracking dyes
  • What is the purpose of DNA ladders containing tracking dyes in gel electrophoresis?

  • To stain DNA samples
  • To amplify DNA fragments
  • To increase the speed of electrophoresis
  • To monitor gel runs and ensure bands of interest are not masked by dyes (correct)
  • When should electrophoresis be stopped in relation to the migration of bromophenol blue dye?

  • Approximately when it has migrated 60% of the gel length (correct)
  • After it migrates 80% of the gel length
  • Regardless of its migration
  • Before it migrates 40% of the gel length
  • Why is monitoring run time crucial in electrophoresis?

    <p>To prevent smallest molecules from migrating off the gel</p> Signup and view all the answers

    What happens if run times are shorter than necessary in electrophoresis?

    <p>Bands will not be completely resolved</p> Signup and view all the answers

    How do DNA ladders with tracking dyes contribute to gel electrophoresis?

    <p>Help monitor gel runs and ensure bands of interest are visible</p> Signup and view all the answers

    What is the typical range for the voltage set in nucleic acid electrophoresis?

    <p>5-10 V/cm</p> Signup and view all the answers

    What is the effect of low voltage in DNA electrophoresis?

    <p>Poor band resolution and diffusion</p> Signup and view all the answers

    Why is it important to monitor run time during electrophoresis?

    <p>To ensure proper band resolution</p> Signup and view all the answers

    What does it mean if the smallest molecules in the sample migrate off the gel during electrophoresis?

    <p>Insufficient band resolution</p> Signup and view all the answers

    What problem can occur if high voltage is applied during DNA electrophoresis?

    <p>&quot;Smiling&quot;</p> Signup and view all the answers

    How does constant voltage assist in running an electrophoresis gel?

    <p>Aids in proper band resolution</p> Signup and view all the answers

    What is the main purpose of gel electrophoresis in molecular biology?

    <p>To identify, quantify, and purify nucleic acids</p> Signup and view all the answers

    Which type of support matrix is ideal for separating macromolecules like nucleic acids and protein complexes?

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

    What property of a biological molecule influences its mobility through an electric field during electrophoresis?

    <p>Shape of the molecule</p> Signup and view all the answers

    In polyacrylamide gel electrophoresis, what is the main advantage of using a smaller pore size?

    <p>Enhanced resolution of smaller molecules</p> Signup and view all the answers

    Which factor does NOT affect the mobility of a biological molecule through an electric field during electrophoresis?

    <p>Temperature of the solvent</p> Signup and view all the answers

    Why is agarose gel preferred for separating macromolecules like nucleic acids and protein complexes rather than polyacrylamide?

    <p>Agarose has a higher resolving power</p> Signup and view all the answers

    Study Notes

    Running Electrophoresis

    • Constant voltage is commonly employed in nucleic acid electrophoresis, with voltage typically set at 5-10 V/cm.
    • The voltage to be applied (V) is equal to the distance between the electrodes (cm) multiplied by the recommended V/cm.
    • Low voltage results in poor band resolution and diffusion, while high voltage can cause "smiling".
    • Run conditions based on fragment size determine the amount of time needed for electrophoresis.

    Run Time

    • The length of the gel, voltage used, and sizes of the molecules in the sample determine the run time.
    • Electrophoresis is usually run until the band of interest has migrated 40-60% of the gel length.
    • Run time should be monitored to ensure the smallest molecules in the samples or standards do not migrate off the gel.
    • DNA ladders containing tracking dyes can help monitor gel runs and ensure bands of interest are not masked by the dyes.

    Electrophoresis

    • Electrophoresis is the transport of charged molecules through a solvent by an electric field.
    • Any charged ion or molecule will migrate when placed in an electric field.
    • Mobility of a biological molecule depends on field strength, net charge, size and shape of the molecule, ionic strength, and properties of the matrix.

    Support Matrix

    • Two common support matrices used in electrophoresis are polyacrylamide and agarose.
    • The support matrices act as porous media and behave like a molecular sieve.
    • Separation of molecules depends on the gel pore size of the support matrix used.
    • Agarose has a large pore size and is ideal for separating macromolecules, while polyacrylamide has a smaller pore size and is ideal for separating smaller molecules.

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    Description

    Learn the fundamental concepts of electrophoresis, which involves the movement of charged molecules through a solvent using an electric field. Understand how this technique is used for analyzing and separating proteins and nucleic acids based on their charge density.

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