Polymorphism: a common and localized variation in the DNA code. For example, if the sequence inside a gene typically reads “…GATTACA…” but many individuals are shown to have “…GATCACA”, the “C” that is normally a “T” is a polymorphism. Polymorphisms occur frequently in the human genome: some are neutral in their effect, some are beneficial, … Continue reading
Tag Archives: human identification
Death: Frederick Sanger (Father of Genomics)
Anyone who works in molecular biology has heard of “Sanger sequencing”, which is a really useful method of sequencing DNA, one base at a time, using “chain terminators”. This method is named after Frederick Sanger, who recently passed away. Here’s a cool video which explains Sanger sequencing. Check out the BBC’s obituary for more details. Continue reading
Supplement for Biologists: The Mitochondrial DNA Mutation Rate
Warning: Not for the general public. I make an exception to my usual rule of writing to the curious lay public for this supplement. I recently wrote about the use of mitochondrial DNA (or mtDNA) in identifying bodies more than a decade old. While researching the topic, I found a lot of seemingly contradictory information … Continue reading
DNA in the Trenches: How Missing Soldiers Get ID’d Decades After Their Deaths
Did you know that over 73,000 American soldiers who fought during World War II are still missing in action1? These are Armed Forces personnel who were sent by their government to fight a war but who never came back. They became prisoners of war (POWs) or were listed as missing in action (MIA). 1,643 U.S. … Continue reading
The Interrogation of Mr. DNA, Part 3 of 3: Detection
Previously, on The Interrogation of Mr. DNA: A woman, found dead in her apartment. Our lab rat, Greg, has managed to amplify 13 repeats in both the victim’s sample and an unknown sample, potentially from her murderer. These repeats differ in length between individuals. Can Greg count them and compare them? Will he accomplish this … Continue reading
The Interrogation of Mr. DNA, Part 2 of 3: Amplification
Previously, on The Interrogation of Mr. DNA: A woman, found dead in her apartment. Blood on her mouth and teeth which may belong to the murderer. At the crime lab, our heroic technician, Greg, has just finished extracting the DNA from the blood spots. No pee breaks on this one, folks. Our show resumes. With … Continue reading
The Interrogation of Mr. DNA, Part 1 of 3: Extraction
Your first perception as you enter the living room is the sound coming from the television. The character exchanges are intimate, from a movie you can’t quite place. The television set’s ever-changing glow stabs the room with occasional bluish bursts of light. Through the half-shut blinds, the pastoral glow of a full moon gently illuminates … Continue reading
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