Question

pre - lab questions/lab: gel electrophoresis

1. shorter strands of dna travel _, farther on the agarose gel than do larger strands.
2. what is the direction of the current under the application of an electric field? (choose one: positive to negative or negative to positive)
3. what is the purpose of the wells?
4. what would happen if di water is used instead of tae buffer?
5. what is the charge of the dna?
6. what colors form the grape kool - aid? (tip: use the information from the kool - aid label)
7. what color form the orange kool - aid? (tip: use the information from the kool - aid label)

Explanation:

1. Smaller DNA fragments move more quickly through the pores of the agarose gel.
2. In an electric field, current flows from the positive terminal to the negative terminal.
3. Wells are made in the gel to place the DNA samples before running the electrophoresis.
4. TAE buffer provides ions for conductivity and maintains pH for DNA separation.
5. The phosphate groups in DNA have a negative charge.

6 - 7. Kool - Aid colors are made by mixing primary food colors as indicated on the label.

Answer:

1. Faster
2. Positive to negative
3. To hold the DNA samples.
4. Without the proper ions in TAE buffer, there would be poor conductivity, and the DNA would not migrate properly through the gel. Also, the pH may not be maintained optimally for the separation process.
5. Negative (due to the phosphate groups in the DNA backbone).
6. Typically, grape Kool - Aid contains red and blue colors to form the purple - like grape color.
7. Typically, orange Kool - Aid contains red and yellow colors to form the orange color.