Thoughts about Barcode & DNA

When I was researching for my next post, I came across a site called the Barcode of Life Data Systems. The term "barcode" commonly used in genetics, prompted me to think, then write. So this post is a separate thought before I write about the silkworm.

In modern times in order to label products, a “barcode” system is used. Do you think that code formed on packages due to the accidental scraping of boxes? Of course not. The information is meaningful and consistent with the product’s identity. It has been put there as an IDENTIFIER of the object. The previous sentence is written in the PASSIVE VOICE; it needs a subject. What subject will you decide is the cause of the action? (Remember the law of cause and effect from science class: “Every material effect must have an adequate cause.”) What or who put the barcode on living beings?

Fill in the blanks and see how much sense you can make: _______put barcodes on cans of peaches, but ______ put(s) barcodes on silkworms. 

I’d be interested in your decision, but mine was: Intelligent people put a barcode on cans of peaches, but Someone more intelligent puts a barcode on the silkworm. In both instances, the barcode serves a purposeful function and is obviously the correct label for the object. In both cases, the barcode is a complex code. On canned goods, it is applied after the contents to serve only as a label. In living beings, the barcode also functions as a set of directions to “build” what it labels. The lines of code are akin to the arrangement of an instruction booklet. This system would be analogous to starting with an empty can, then pasting on a barcode and having that code dictate the creation of the peaches inside the can!

Due to space limitations, I’m including just a bit of code for the silkworm so you can visualize it.    

CGAAAATGAATTTATTCTACAAATCATAAAGATATTGGAACATTATATTTTATTTTTGGTATTTGATCAGGAATAATTGGAACATCTTTA---

AGACTTTTAATTCGAGCTGAATTAGGAAATCCAGGATCATTAATTGGAGAT---

Skip the following if you understand what the genetic code is and why scientists assign a letter to each nucleotide.  The following is excerpted for background information from the U.S. Fish and wildlife Service from a website: Genetic Monitoring for Managers. The article is: “Principles of Conservation Genetics” at: http://alaska.fws.gov/gem/principles_I.htm

The genetic code is like a mystery novel, history text, and time log all wrapped into one. The goal of a geneticist is to learn how to read these books written in a simple* 4 letter alphabet and decode critical information about the species under study. 

DNA, or deoxyribonucleic acid for those that want to impress their friends, is composed of a sequence of molecules called nucleotides. There are only 4 different nucleotides in DNA that create the genetic code and these are often referred to by a single letter: Adenine (A), Thymine (T), Cytosine (C), and Guanine (G). Yes, the text for your entire body is written in a code made up of 4 letters!**

*I object to the word “simple.” Computer code is written in “only” two letters and look what that accomplishes. The use of four-letters sounds streamlined, not simple.

**Note the passive tense (“is written”). That phrasing begs the question, WHO wrote it?