Mary performs a PCR reaction and runs it on an agarose gel, using 100-bp ladder
ID: 187126 • Letter: M
Question
Mary performs a PCR reaction and runs it on an agarose gel, using 100-bp ladder as her molecular weight standard. She images the gel using UV light and sees NO bands (no band in her PCR reaction and no bands for her ladder). Which of the following could explain these results? Explain each answer.
1. Mary forgot to add Gel Red when pouring the gel.
2. Mary's PCR product had an unusually high % of G and C bases.
3. Mary connected the electrodes to her gel incorrectly, swapping the positive and negative poles.
Explanation / Answer
Two possible reasons for the same are:
1. Mary forgot to add Gel Red:
Gel Red binds with nucleotides and glows when exposed to UV radiation. So inability to see bands may be due to missing addition of gel red.
2. Mary connected the electrodes got her gel incorrectly:
DNA is a negatively charged molecules that moves towards anode. If the terminals have been connected with opposite electrodes DNA Will fail to migrate hence Will not separate out into bands.