Think Gene Think Gene RSS

a bio blog about genetics, genomics, and biotechnology

DNA Helix

To Describe a Human

August 31st, 2008 by Andrew Yates

Slobodan Cekic writes in response to How Much Data is a Human Genome:

Now, please do take a look at your fingertips. You ll see the fine lines of your fingerprint pattern. It is unique, and can be used to identify a human; so fine and even much finer structures are defined in your organism.
Now, how high would be only 3D positional information content needed to describe a human?

You would need to position single cells, define the inner structure of particular cell types, describe the form of single nerve cells (dendrites)…etc

Now how many cells are there in the human organism?

Without any calculation, we can see the information quantity to describe a human in uncounted Terabytes. Human chromosomes contain , as calculated here, 740 MB.

So, why for the God’s sake do we believe that the whole of our hereditary information resides in the genes?

740MB is the size of a reference human haploid nucleotide base string, not the data necessary to describe a mature human.

We believe that most of our hereditary information resides in genes because it does. However, a genome, as you say, cannot possibly fully describe a mature human. A genome is more like a brief mathematical equation used to produce beautifully complex fractal design when fed with ambient noise and interpreted as colors and coordinates on a screen.

Arguably, as other commentators have noted, this isn’t enough to describe a genome. Cytosine can be methylated —like a fifth base. Sometimes, a sequencing machine is unable to assert a base, and an extra bit would necessary to report these “no calls.”

But in reality, humans don’t have a “reference genome.” Almost every cell has its own pair of genomes, and these tend to diverge as they accumulate mutations and errors. To be pedantic, to record your Real and Complete Human Genome, one would have to sequence every strand of DNA in your body instantaneously.

Yet, these trillions of strings of millions of bases can be understood as that 740MB reference human genome like a field full of flowers can be understood as a photo of daisy.

Comments
Tags:

Viewing 6 Comments

Trackbacks

  1. Hey junk people, I accept your challenge (part I) « The Sciphu Weblog
    September 23, 2008 @ 9:43 am

    [...] is “junk”, I say that the evidence indicating otherwise is strong enough to allow for speculation on (and research into) possible functions. In a recent discussion with Professor Larry Moran over [...]

close Reblog this comment
Powered by Disqus · Learn more