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DNA Fingerprinting with Example Lab Data

There are various ways in assessing DNA and its components. One widely used is electrophoresis, which utilizes electricity to measure the length of DNA fragments. This mechanism can be used for identification either for unknown diseases or human DNA, determining an inherited disease or finding cures for such diseases (National Health Museum).

What is Electrophoresis?

How is DNA assessed?

See image for specific column for details. The ladder is usually placed nearest the right or left side of the gel. Conducted by Kendall McCarthy, Chloe Yap, and Amy Truong


The Gel was ran at approximately 113-117 volts.

Every ladder has its own defined or known measurements of DNA (usually measured in base pairs). In this ladder, there are 8 segments seen, which are measured at:

(*farthest from the well at middle of photo)

570 bp = 0.570kbp*
725 bp = 0.725 kbp
2027 bp = 2.027 kbp
2322 bp = 2.322 kbp
3000 bp = 3.000 kbp
6557 bp = 6.557 kbp
9416 bp = 9.416 kbp
23,130 bp = 23.130 kbp**

(**closest to the wells at the bottom of the photo)

Closest to the wells (bottom of the photograph is the higher DNA fragments). Remember, the larger the DNA segments, the greater the bp, the slower it will travel due to its inefficiency in traveling through the lattice matrix of the Agarous Gel.

As you can see, each column has a few or none (blank column) segments. It is expected that the blank has none considering there shouldn’t have been any DNA in there, if there were any sort of contamination in the blank, any band shown in the blank would then be disregarded in the other columns as well. However, usually, we would have to redo because it is dependent upon how the contamination occurred (ex: not changing tips).

As you can see in our unknown, there are 3 bands that are arranged similar to the bands found in BCV. It is then “presumed,” from this procedure that the unknown virus is BVC. In lab, we would consider to do other techniques to assess for the true congruency between BCV ad the unknown virus. Assuming that unknown virus is BCV is not classified as truly conclusive. However, for the sake of this experiment, it is.

Measuring the band segments is simple, you literally try to extrapolate the bands according to the ladder. In a rough estimation, we found:

CPV: 650 bp and 2322 bp

BCV: 650 bp; 2322 bp; and 3000bp

MIOV: 2027 bp

Unknown: 650 bp; 2322 bp; and 3000bp

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