In a standard DNA extraction protocol, what is the primary purpose of adding a lysis solution?

• A. To separate DNA fragments by size using an electric field in a gel matrix
• B. To break open cells and nuclei and disrupt membranes so DNA is released into solution
• C. To amplify the extracted DNA using thermostable DNA polymerase
• D. To selectively degrade DNA while leaving proteins intact

Answer: (B)

Verified step by step guidance

1. Understand the goal of the DNA extraction protocol, which is to isolate DNA from cells for further analysis.
2. Recognize that cells and nuclei are enclosed by membranes that protect the DNA inside, so these barriers must be broken down to access the DNA.
3. Identify that the lysis solution contains chemicals (such as detergents and enzymes) that disrupt the lipid bilayers of cell and nuclear membranes, effectively breaking open the cells and nuclei.
4. Note that breaking open the cells releases the DNA into the solution, making it accessible for subsequent steps like purification and analysis.
5. Distinguish this step from other processes such as gel electrophoresis (which separates DNA by size), PCR amplification (which copies DNA), or selective degradation of DNA, none of which are the primary purpose of the lysis solution.