Nucleic Acid Electrophoresis Quiz
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Questions and Answers

What is the reason longer nucleic acid molecules migrate more slowly during electrophoresis?

  • They are less negatively charged
  • They experience more resistance within the gel (correct)
  • They are less reactive to the electric field
  • They are larger in size

    • What is the role of a DNA restriction endonuclease in nucleic acid electrophoresis?

  • It increases the reactivity of nucleic acids
  • It cuts large DNA molecules into smaller fragments (correct)
  • It reduces the size of the gel medium
  • It enhances the negative charge of nucleic acids

    • What determines the migration of nucleic acids during electrophoresis?

  • Shape of the molecule
  • Color of the molecule
  • Density of the molecule
  • Size of the molecule (correct)

    • What is the main responsibility of the gel matrix during electrophoresis?

    <p>Separation of DNA by size</p> Signup and view all the answers

    What type of gels are commonly used for DNA electrophoresis?

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

    What separates nucleic acid molecules in gel electrophoresis?

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

    What is the main function of DNA in living cells?

    <p>Act as the blueprint for protein synthesis</p> Signup and view all the answers

    What does polymorphic DNA refer to?

    <p>Chromosomal regions that vary among individuals</p> Signup and view all the answers

    What was the pioneering work of Dr. Alex Jeffreys related to?

    <p>DNA fingerprinting</p> Signup and view all the answers

    What was the first application of DNA fingerprinting as a forensic tool?

    <p>United Kingdom in 1984</p> Signup and view all the answers

    What is the best way to ensure accuracy in pipetting?

    <p>Using the pipette correctly and periodically recalibrating the volume</p> Signup and view all the answers

    What is precision related to in pipetting?

    <p>Having a well-functioning and well-maintained pipette and using a correct and consistent technique</p> Signup and view all the answers

    What is the purpose of mastering pipetting-by-numbers practice in the experiment?

    <p>To start by mastering the use of a micropipette</p> Signup and view all the answers

    What skill should be developed to maximize the accuracy and precision of experiments?

    <p>Using a pipette correctly and maintaining it well</p> Signup and view all the answers

    What technology did the FBI establish in 1990 for comparing crime scene DNA to convicted offender profiles?

    <p>Combined DNA Index System (CODIS)</p> Signup and view all the answers

    What is the initial method used in forensic DNA fingerprinting that required large amounts of DNA and took several days to complete?

    <p>Restriction fragment length polymorphism (RFLP) analysis</p> Signup and view all the answers

    What technology has been used in forensics since it requires less DNA and is cheaper and less time-consuming?

    <p>Polymerase chain reaction (PCR)</p> Signup and view all the answers

    What does PCR amplification involve in forensics?

    <p>Taq DNA polymerase, primers, and the target DNA region</p> Signup and view all the answers

    What are pipettes used for in laboratories?

    <p>Measuring and manipulating liquids</p> Signup and view all the answers

    What type of pipette is used for approximate measurements in laboratories?

    <p>Graduated pipettes</p> Signup and view all the answers

    What technology is equipped with piston displacement and used for smaller volume reactions in molecular and microbial biology experiments?

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

    What type of pipette offers additional capabilities for preparing multiple samples and working with specific solutions?

    <p>Multichannel pipettes</p> Signup and view all the answers

    What is the purpose of robotic pipettes in laboratories?

    <p>Automated liquid handling</p> Signup and view all the answers

    What innovation in pipette design has led to adjustable piston heights for measuring a range of volumes?

    <p>Disposable pistons</p> Signup and view all the answers

    What are the major steps of pipetting?

    <p>Prepare, aspirate, dispense, re-aspirate and re-dispense, and purge</p> Signup and view all the answers

    How is a vacuum created for aspirating during pipetting?

    <p>By pushing the plunger down</p> Signup and view all the answers

    What is the purpose of using the first 'soft' stop when aspirating?

    <p>To match the set volume for accurate measurement</p> Signup and view all the answers

    What should be done before releasing the plunger during dispensing?

    <p>Lift the tip out of the solution</p> Signup and view all the answers

    What do the 'golden rules' of pipetting emphasize?

    <p>Using the correct pipette and tip for the volume, avoiding contamination, and practicing good ergonomics</p> Signup and view all the answers

    How is accuracy defined in the context of multiple pipette measurements?

    <p>Refers to the average being close to the intended amount</p> Signup and view all the answers

    What does precision refer to in pipetting?

    <p>Describes the reproducibility of the measurement</p> Signup and view all the answers

    What is the role of robotic pipettes in laboratories?

    <p>Aliquot a specified volume to multiple tubes or wells and some are equipped with artificial intelligence</p> Signup and view all the answers

    What is the purpose of the 'golden rules' of pipetting?

    <p>To ensure accurate and precise pipetting</p> Signup and view all the answers

    What does accuracy describe in the context of measurements?

    <p>How close a measurement is to the true value</p> Signup and view all the answers

    What is the main purpose of precision in measurements?

    <p>To ensure the reproducibility of the measurement</p> Signup and view all the answers

    What is the responsibility of the gel matrix during electrophoresis?

    <p>To separate nucleic acid molecules based on size</p> Signup and view all the answers

    Study Notes

    Nucleic Acid Electrophoresis: Factors Affecting Migration

    • Nucleic acid samples are prepared by removing enzymes that may affect molecule separation
    • DNA fragments of different lengths are visualized using a fluorescent dye specific for DNA
    • Gel electrophoresis separates nucleic acid molecules by size and is commonly used for DNA analysis
    • Agarose and polyacrylamide gels are commonly used for DNA electrophoresis
    • Capillary electrophoresis is important for high-throughput DNA sequencing
    • Factors affecting nucleic acid migration include gel pore size, voltage, buffer ionic strength, and intercalating dye concentration
    • Gel electrophoresis separates DNA based on molecule size, with smaller molecules moving faster
    • Supercoiled DNA moves faster than relaxed DNA due to its compact conformation
    • Ethidium bromide concentration affects the migration of circular DNA in gel electrophoresis
    • Gel concentration affects DNA migration, with higher concentrations improving resolution for smaller DNA fragments
    • The limit of resolution in gel electrophoresis depends on gel composition and field strength
    • Circular DNA can be resolved by changing the agarose gel concentration

    Forensic DNA Fingerprinting and Pipettes

    • In 1990, the FBI established the Combined DNA Index System (CODIS) for comparing crime scene DNA to convicted offender profiles
    • Forensic DNA fingerprinting involves collecting blood or tissue samples, treating them with a buffer solution, and analyzing the DNA
    • Initially, the restriction fragment length polymorphism (RFLP) analysis was used, which required large amounts of DNA and took several days to complete
    • Polymerase chain reaction (PCR) has since been used in forensics, requiring less DNA and being cheaper and less time-consuming
    • PCR amplification involves Taq DNA polymerase, primers, and the target DNA region, and is performed in a thermal cycler
    • PCR is used to analyze highly variable DNA regions, such as variable number of tandem repeats (VNTR) and short tandem repeats (STR)
    • Pipettes are used in laboratories to measure and manipulate liquids
    • Pasteur pipettes are used for approximate measurements, while graduated pipettes are designed for higher volumes
    • Micropipettes, equipped with piston displacement technology, are used for smaller volume reactions in molecular and microbial biology experiments
    • Some pipettes, like multichannel and positive displacement pipettes, offer additional capabilities for preparing multiple samples and working with specific solutions
    • Robotic pipettes also exist for automated liquid handling in laboratories
    • Innovations in pipette design have led to adjustable piston heights for measuring a range of volumes and disposable pistons for specific applications.

    How to Use Robotic Pipettes and Adjustable Micropipettes

    • Robotic pipettes can aliquot a specified volume to multiple tubes or wells and some are equipped with artificial intelligence to carry out entire experiments.
    • The major steps of pipetting are: prepare, aspirate, dispense, re-aspirate and re-dispense, and purge.
    • To aspirate, create a vacuum by pushing the plunger down, and make sure to use the first "soft" stop to match the set volume for accurate measurement.
    • For dispensing, place the tip and push the plunger down to increase pressure, and remember to lift the tip out of the solution before releasing the plunger.
    • Most biotechnology experiments involve preparing reactions by going through these steps multiple times for multiple reagents.
    • There are seven "golden rules" of pipetting, including using the correct pipette and tip for the volume, avoiding contamination, and practicing good ergonomics.
    • Accuracy describes how close a measurement is to the true value, while precision describes the reproducibility of the measurement.
    • In the case of multiple pipette measurements, accuracy would refer to the average being close to the intended amount, and precision would refer to all values being close together.

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    Description

    Test your knowledge of nucleic acid electrophoresis with this quiz. Explore the factors that affect migration of DNA fragments, the types of gels used, and the techniques for visualizing molecules of different sizes.

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