How movies mislead you about DNA
Let’s talk about facts that movies mislead you showing DNA magics
Let’s talk about DNA super security movie magic tricks in brief. I will make this a small presentation without exact figures or references (you can study though). Thought of sharing this after 6 months doing my PhD in the area of genome assembly and assembly graph.
You might have seen in movies that DNA rolls in a long helical line. Well helical structure is something fundamental. However, DNA sequence is not continuous. It is usually broken into chromosomes (we have 46, 23 from each parent). So simple we got 23 couples of DNA sequences.
Read DNA and unlock the door
The modern forms of reading DNA, we call is sequencing is hardly capable of reading the sequence at all. Usually best case is like you have a sequence of length 25,000 in length with many errors. So not accurate. Talking about Human its 3,000,000,000 or 3 billion DNA molecules in length. So far we do NOT have a complete DNA reference for human (There are bits and pieces missing, google GRCH38 its the latest reference release). Also a round of such sequencing usually cost a lot. I mean more than US $ 1000. Not a very good option. Moreover, the process takes ages. You don’t want to wait that long for a security clearance.
DNA from the foot marks or whatever that is left on the scene
In my line of work, researchers struggle when there is contamination. Even a clean sputum sample would carry a whole set of micro-organisms which render them useless. It is also the case that we don’t usually release any DNA carrying items to the environment, unless we bleed, spit or “never mind mentioning”. So its not as easy as it sounds or any faster than an interrogation.
How does the “Is this my kid?” thing works
Well for crime scene related matters or paternity test DNA is not sequences at all. Because its very expensive and time consuming. Instead chemical engineering techniques are used. Something similar to putting a pH paper and seeing the acidity (Not going into details).
Guess I broke a bit of “Movie DNA Myths” and please keep in mind that this is not an in-depth review. Hope you enjoyed! :) Cheers!