Why does smearing occur in dna

Keep within cycles. But this could be one of your issues. Use fresh reagents — grab new aliquots because you might be encountering contamination that is causing degradation. After taking a look at our series of articles, you may not have to rely so much on the PCR good luck charms and superstition to get you through the task.

Increase your primers. Then came college, and the revelation that the adults in my past were right all along. But since math feels less tangible, I fell for biology and have found pure happiness behind my desk at GoldBio, learning, writing and loving everything science. Category Code: Leave Feedback. Related Articles. In all of its grandeur, polymerase chain reaction PCR grants scientists power over genome.

Tip 2: Try the post-staining protocol To avoid any interference the dye may have on DNA migration, we recommend using the post-staining protocol.

Avoid overfilling gel wells to prevent smearing of DNA down the surface of the gel. Pour a lower percentage agarose gel. Higher molecular weight DNA separates better with a lower percentage gel. Change the running buffer. When it comes to smeared results, one likely culprit is a poorly prepared gel. A satisfactory gel polymerizes evenly, producing a uniform matrix throughout the gel in the casting tray.

If part of the gel — usually the lower half — sets before the scientist finishes pouring the entire tray, the resulting gel will be uneven and yield smeared results. Before loading samples into the wells, those samples must be dilute enough to run through the gel without overflowing the wells.

If a loaded sample is too concentrated because the scientist forgot to dilute it or used an improper dilution factor, the fragments will be too large for the wells and produce smearing. Smearing also results from poor sample quality. For example, a DNA sample contaminated with protein or containing too much salt may produce smearing. Degraded or denatured samples also yield poor results, including smeared bands. Gel electrophoresis is an amazing way for scientists to visualize digested samples and determine fragment size.

Careful preparation of both the gel and the sample minimizes the possibility of smearing and yields clear bands ideal for scientific interpretation. Melissa Mayer is an eclectic science writer with experience in the fields of molecular biology, proteomics, genomics, microbiology, biobanking and food science.

She has also served as interim associate editor for a glossy trade magazine read by pathologists, Clinical Lab Products, and wrote a non-fiction YA book Coping with Date Rape and Acquaintance Rape. She has two books forthcoming covering the neuroscience of mental health.