As opposed to the gel whose picture I posted last week, this one is much more useful. If you’ve ever watched any sort of forensic investigation show (CSI, Cold Case, Without a Trace, Blah Blah Blah), much of the DNA “fingerprinting” they pretend to do is actually done using similar techniques to those we used to obtain the picture above. In the least technical terms, DNA is cut into pieces using enzymes. These pieces will migrate a particular distance depending on their weight. The map that results will be unique for a given individual (in practice, there is the possibility that this isn’t true and so many test runs with various enzymes are done). In this case, we are using bacterial plasmid DNA rather than eukaryotic linear DNA, but the basic concept still holds up.


I’m going to set a bad precedent by responding to comments:Dan asked why the DNA glowed. Well, the DNA is stained using a phosphorescent dye before running the gel. We then place it on a bed of UV light and capture it on upper-spectrum sensitive Polaroid film. This isn’t the best way to flag the DNA strands and most forensic labs use radioactive isotopes; but having some idiot that can’t remember whether to incubate something for 20 or 40 minutes handling radioactive materials isn’t the best idea.Did you say smudge? Smudge? You’d think that before your discarded a technique, you’d at least learn it’s name. Blending, hrm sorry, smudging is the best way to achieve a smooth gradient with dry media (especially using pastels). I’m not very good at it yet (they might look like smudges) but it looks amazingly photorealistic when done correctly. Using different pencils to get your tones is something you have to do anyways. If you can really get a smooth tone change without blending, I’d like to see it (and I mean truly smooth). Of course, you might have meant cross-hatching, which looks completely different. Or, I might just be wrong. (I’ve never been a good artist, but grew up among what seemed like a million of them. I’ve seen the excellent, the good, the fair, and the very very bad. I’ve also learned that what one artist says is usually heresy to another one across the street.)I first used a wrapped piece of copy paper as a tortillion, but I bought a pair of blending stumps (about a buck). I also bought a bristol board pad ($3.50), 4H, 2B, 4B pencils ($0.75 each), and a pink eraser ($0.50). I already owned an HB pencil, a kneaded eraser, and some sandpaper. This stuff looks like it will last me forever (except the paper).I’m working on a new feature for the weekend. Though I might post shitty artwork earlier.Ja.