Lab 13 DNA Extraction Experiment

Study Guide for Lab 13: DNA Extraction Experiment

Overview

  • This laboratory experiment focuses on the techniques used in DNA extraction and fingerprinting. Each step involves specific solutions or reagents that play crucial roles in the process of obtaining and analyzing DNA.

DNA Extraction Process

  1. Obtain Cheek Cells

    • The initial step involves collecting cells from the inside of the cheek, which serves as a rich source of DNA for extraction.

  2. Add Extraction Solution (Detergent)

    • Purpose:

      • The detergent solution is crucial for cell lysis, which is the process of breaking down the cell membrane.

    • Functionality:

      • The detergent disrupts the lipid bilayer of the cell membrane, allowing cell contents, including DNA, to leak out into the solution.

  3. Add Protease (Meat Tenderizer) Solution

    • Purpose:

      • The protease solution helps in degrading proteins present in the cell and any DNA-damaging enzymes.

    • Functionality:

      • By breaking down these proteins, protease facilitates the separation of nucleic acids (DNA) from the protein material, ensuring a cleaner extraction of DNA.

  4. Add Cold Alcohol

    • Purpose:

      • Cold alcohol is employed to precipitate the DNA molecules from the solution.

    • Functionality:

      • When alcohol is added, it causes the DNA to clump together and become visible as a precipitate, making it easier to collect.

DNA Fingerprinting Experiment

  • Definition:

    • A DNA fingerprint is unique to each individual and can be used for identification purposes.

    • It relies on the analysis of polymorphic regions within the DNA, which are segments that exhibit significant variations among different people.

Basic Steps of DNA Fingerprinting

  1. DNA Extraction from a Sample

    • DNA can be extracted from various sources, including blood or cell samples obtained through the DNA extraction process.

  2. Amplification of Polymorphic Regions Using PCR

    • Polymerase Chain Reaction (PCR):

      • A technique employed to amplify specific DNA segments (polymorphic regions) to generate enough DNA for analysis.

  3. Fragmentation of DNA Using Restriction Enzymes

    • Definition:

      • Restriction enzymes are specialized proteins that recognize and cut specific DNA sequences at designated locations.

    • Functionality:

      • This process produces distinct DNA fragments that vary in size depending on the individual’s genetic makeup.

  4. Separation of DNA Fragments by Electrophoresis

    • Process:

      • DNA fragments are separated on an agarose gel using electrophoresis, where an electric field causes the negatively charged DNA to migrate towards the positive end of the gel.

    • Note:

      • Smaller DNA fragments move faster through the gel, allowing for size differentiation among the fragments.

  5. Visualization of DNA Using UV Light Reader

    • The separated DNA fragments are visualized using a UV light reader, making it possible to analyze the unique pattern of bands, which constitutes the DNA fingerprint.

Important Definitions

  • Restriction Enzymes:

    • Enzymes that identify specific nucleotide sequences in DNA and cleave the DNA at those points, enabling the generation of DNA fragments necessary for analysis.

  • Gel Electrophoresis:

    • A laboratory technique used to separate mixtures of DNA, RNA, or proteins based on their size and charge by applying an electric current to a gel matrix.