A molecular technologist has run a vertical get. While analyzing the gel, the technologist notices that the bands in the outer lanes did not run as far as similar-sized bands in the inner lanes, so the bands looked like a smile on the gel. What is the explanation for this? a. Samples were loaded into the inner wells first and got a head start moving down the gel. b. A larger volume of sample was loaded into the outer wells so that they ran slower. c. The electrodes in the middle of the gel were working better than at the edges of the gel. d. The temperature across the gel was not constant, so the inner wells were warmer.

d. The temperature across the gel was not constant, so the inner wells were warmer.

Explanation:

The question above is probably talking about the bands observed on an agarose gel, with molecules that have gone through the process called PCR (polymerase chain reaction). In this process the DNA is put together with other molecules, goes to a device known as a thermocycler that heats and cools the material contained therein at pre-established temperature cycles.

After this process, the molecule is observed in bands within an agarose gel. The temperature during the PCR process is extremely important for the bands to have the appropriate shape and size. As we can see from the question above, the bands the coach has observed are not of an appropriate size.

When the temperature is not appropriate, the gel wells may have a foreign shape. The gel wells in the above question have a smile shape, so we can say that the temperature in the gel was not constant, so the internal wells were warmer.