Question

Southern Blotting uses a nitrocellulose membrane to absorb the DNA from the gel. What makes the DNA move towards the nitrocellulose membrane?

• A. Movement of liquid in the gel tank towards the blotting paper
• B. Nitrocellulose membrane is positively charged
• C. Nitrocellulose membrane contains DNA probes to which DNA fragments attach
• D. The gel is placed above the membrane, and gravity pulls the DNA below to the membrane

Answer 1

Answer: (A), (B)

Nitrocellulose membrane is positively charged

Blotting paper is kept above the nitrocellulose membrane, which is placed above the gel. The fluid moves up the gel by capillary action moving the DNA fragments along with it. Since nitrocellulose membrane is positively charged, negatively charged DNA sticks on to it.