DNA Extraction Lab DNA Source = wheat germ Wheat germ contains many nutrients Wheat bran contains fiber White flour has germ and bran removed, whole wheat flour does not—it is more nutritious

Water Temperature Hot water softens the phospholipids (fats) in the cell membranes and nuclear membranes within the germ (embryo) Inactivates an enzyme that normally cuts DNA into small pieces (60°C) If too hot it would cause DNA to fall apart (~80 °C)

Detergent Contains a chemical (sodium laurel sulfate), which cleans dishes by removing fats and proteins Pulls apart cell membrane and nuclear membrane

Detergent continued Both grease and soap are made of molecules with hydrophilic heads and hydrophobic tails. PAIR SHARE: What do you think hydrophobic and hydrophilic mean? Hydrophilic= likes water Hydrophobic= hates water They form spheres with tails facing inward. Soap captures grease and forms greasy soap ball.

Cell Membrane Like a grease ball, cell membrane has lipids (fats) with head and tail—this time there are two layers.

Cell Membrane and Soap Just as soap disrupts grease, it also disrupts cell membranes.

Alcohol Alcohol causes DNA to clump together in the solution. It also causes DNA to separate from the other cell components, which are left behind in the water solution.