Final answer:
The two layers formed during phenol and chloroform extraction in DNA extraction are the aqueous phase (containing DNA) and the organic phase (containing phenol and chloroform). The aqueous phase, which contains the DNA, migrates to the top, while the organic phase, with phenol and chloroform, migrates to the bottom of the tube during centrifugation.
Step-by-step explanation:
During the DNA extraction process, phenol and chloroform are often used to separate the DNA from other cellular components. After the addition of these reagents, the mixture is centrifuged, leading to the formation of two distinct layers in the tube. The aqueous phase, which is the upper layer, contains the DNA dissolved in water.
This layer migrates to the top because it is less dense than the organic phase and does not mix well with phenol and chloroform. The organic phase, composed of phenol and chloroform, is denser and migrates to the bottom due to its immiscibility with water.
The separation into distinct layers is achieved based on the differences in density and solubility of the components. Phenol and chloroform have a higher density and are immiscible with water, causing them to form a separate layer at the bottom.
Meanwhile, DNA, being water-soluble, remains in the aqueous phase, which rises to the top. This separation facilitates the isolation of DNA from other cellular components, allowing for a cleaner and more efficient extraction process.