EtOH reduces the solubility of DNA
EtOH reduces the solubility of DNA
- DNA normally stays dissolved in water because DNA is surrounded by a shell of water molecules, because water sticks to its charged phosphate backbone
- When ethanol is added, it competes with water and reduces the number of water molecules that can surround DNA
- So the “protective water coat” around DNA becomes weak or incomplete
- Without that coat, DNA strands are no longer well-separated and stabilized in solution
- A salt (like NaCl or sodium acetate) is usually already added in the extraction mix, and it helps reduce repulsion between DNA strands, making clumping easier
- Once clumped, DNA becomes visible as a white precipitate, which can be collected easily
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