A Good Girl's Guide to Murder - DNA Fingerprinting

Okay,

A crime has happened in your little town of Kilton. Instead of doing the logical thing and calling the police and then running as far as you can from the murderous town , you decide to solve the crime on your own. Why? howelse will the novel proceed if the protagonist gives up in the start itself?

In this blog , this writer will help you with your investigation by bringing in the science support you need! aka DNA fingerprinting

( Is this blog inspired by this writer's obsession with crime novels? yup)

99.9 percent of the sequencing of DNA in all humans are the same. That's the reason why all of us have exactly two eyes, two hands and one nose- the common features match. The left over 0.01 percent is what makes as unique individuals.

This 0.01 percent is used for various methods of identification or differentiation of a singular person for various reasons.

DNA fingerprinting involves identifying differences in some specific DNA sequence called Repetitive DNA ( a part where a small part is repeated many times). This is seperated from the bulk genomic DNA by centrifuge (the horizontal ferris wheel for microbes)

This is now considered as satellite DNA. These sequences form the basis of DNA fingerprinting cause they show polymorphism ( which is variation in the genetic level)

so these are the steps, in a simple gist, used for DNA fingerprinting

1. Isolate the DNA ( which we get from hair, blood etc)

2. Digestion of DNA - In this step an enzyme called ' Restriction Endonuclease' is added which basically cuts the DNA

3. These fragements are seperated using electrphoresis. DNA is negative and hence is attracted towards the anode.

4. Transfer the seperated DNA on a membrane - nylon

5. These are hybridised with another type of DNA which help in easier identification in the next step

6. Detection of the hybridised DNA fragments by autoradiography

The autoradiogram gives many bands of different sizes, These give a characteristic pattern for an individual DNA.

and to all my fellow aggtm fans