Biotech 2nd Edition Sample Ch. 4 Biotechnology Sample Ch. 4 - Page 5

Figure 4.3.  Any samples containing DNA, RNA, or protein should be kept cold to decrease the amount of sample degradation. Figure 4.4.  DNA is clear in solution. As it gets tightly wound on the rod, solvent is pushed out and it starts to look white. Photo by author. Photo by author. Procedure In your notebook, make a data table to record all the data from the observations of DNA at different points in the extraction. 1. Using the TE buffer as the solvent and the C1 V1 = C2 V2 equation, determine how to make 2 mL of 2 mg/mL from a 4-mg/mL salmon sperm DNA solution. In your notebook, record the calculations and a drawing of how to make this dilution. 2. Prepare the diluted salmon sperm DNA solution in a prechilled, clean, 50-mL beaker. You will be using this 2-mg/mL DNA solution in the next step. 3. Describe the appearance, color, viscosity, etc, of the 2-mg/mL salmon sperm DNA. Add these data to the data table. 4. Using a micropipet, add 500 µL of 5 M NaCl solution to the salmon sperm DNA. Mix by swirling. 5. Keep everything as cold as possible (see Figure 4.3). Slowly trickle 4 mL of EtOH down the side of the beaker containing the DNA and NaCl. Do not mix the alcohol and DNA layers. 6. Observe the interface between the two solutions. You should see a layer of alcohol on the top of the layer containing the DNA and NaCl. Do not mix the two layers. Describe what the layers look like. Add these data to the data table. Note: Before spooling, add 2 mL of TE buffer to a 15-mL conical tube for use in Step 11. ˂TX