The Hierarchical Structure of DNA

Introduction
All life on Earth is based on building blocks, known as DNA (deoxyribonucleic acid), which exists in the form of a double helix. DNA is a highly elaborate and modular molecule with different levels of hierarchical complexity. In this post, we will examine some of the concepts about DNA. For those of you that are interested in fields such as astrobiology, transhumanism, and similar areas, it’s important to understand DNA as it has a direct bearing on much of the research being done in these emerging sciences today.

DNA Composition
DNA is made up of nucleotides, which are themselves constructed from a molecule of sugar, a molecule of phosphate, and a base. The base is the most crucial part of the molecule as it is essentially the carrier of the genetic information, that when combined with other bases, codes your genetic makeup. Simply put, DNA is an amazing biological molecule, which essentially makes you… you.

Image Credit: University of Utah

Bases
As mentioned, DNA at its simplest level is made up of a combination of bases; Adenine (A), Cytosine (C), Guanine (G), and Thymine (T). These bases exist in a chain on each strand of the double helix and join up in between the strands as complementary pairs of A-T and C-G. This sequence of base pairs is what codes for proteins to be made in your body, and thus is responsible for your appearance, your metabolism and thousands of other functions and features.

Genes
Sequences of bases that code for specific proteins to be produced are known as genes. They can be anywhere from only a few bases in length, to several million, with the average length in the human genome being approximately 3,000. For example, you can have a gene that determines eye color, or a gene that dictates the pigment of your skin. Different forms of a gene are known as alleles, so the gene for eye color has green, blue and brown alleles.

DNA Strands
A DNA strand is made up of thousands upon thousands of genes, and also what is known as junk DNA. This junk DNA does not have a function, or rather, it does not have a function that is currently understood or known of in the scientific community. These DNA strands form a double helix, which is two strands of DNA joined at their complementary bases, in a spiral structure.

Images and animations are courtesy of the National Human Genome Research Institute’s Talking Glossary.

Chromosomes
Chromosomes are tightly wound bundles of DNA strands, that look like two arms joint at the centromere, with the short arm designated “p”, and the long arm designated “q”. Two chromosomes join at the centromere to form a chromosome pair, which structurally resembles an “X”. The chromosomes are found in the nucleus of the cell, from where they replicate to form duplicates of themselves during cell division, or take part in the transcription/translation process whereby proteins are created from the genetic code.

DNA is complex
DNA, even when broken down into its constituent parts is incredibly complex and because of this, errors can easily creep into the code. Genetic disease and cancer typically come about due to these errors in the genome, and are exponentially copied during the copying and division of cells. So, DNA and its complexity are both a blessing and a curse but without it, life as we know it would not be possible.

Helpful DNA-related Resources:

  • http://twitter.com/jason_d_carr/status/270525134098558976/ Jason Carr (@jason_d_carr)

    Let’s Explore the Hierarchical Structure of DNA | wired cosmos http://t.co/RgWNfRCE

  • http://jameswharris.wordpress.com Jim Harris

    Can we think of DNA as a programming language? Is DNA like assembly language, and proteins like higher level languages like Java, python, C++? Or is DNA more like building blocks, or tinker toys? I suppose we could think of atoms and molecules as the building blocks, and DNA an advance structure like a Ferris wheel.

    At what point in biology does the mechanical turn into information theory? We hear all the time about genes being discovered that are link to some function, like eye color. But I have to take it on faith that bits of chemicals can actual describe how an eye is made and color the iris. We know replicating cells eventually produce a human body, but how close are we to knowing how the cells do everything they do?

    • Jason Carr

      I think it’s exactly like a programming language Jim…essentially 1s and 0s. This is why I think we’re moving in the right direction in terms of AI. As for understanding cells and everything they do, I think it’s about like the brain…we have a long way to go. I’m hopeful that someone will successfully map the mind within a decade but it may take longer. The same applies to cells although it may happen much faster. Once the mind is mapped however, you have to wonder if it will gain consciousness and if so, what are the ethical implications we need to consider? Either way, it’s important to understand DNA in all of these efforts. That’s the foundation to life as we know it. Whether this will apply to extraterrestrial life remains to be seen as well, of course. I find it all fascinating. Great to hear from you JIm!

  • http://jameswharris.wordpress.com Jim Harris

    I think there’s a lot of hidden complexity that we’re not imagining yet. I totally expect AI to succeed, but it might be awhile still. I don’t think we can write programs that anticipate all events. We need to learn how to write programs that learn and evolve. I don’t think consciousness and create consciousness, the complexity is too create. I think it must evolve.

    Did you read this:

    http://www.theatlantic.com/technology/archive/2012/06/a-perfect-and-beautiful-machine-what-darwins-theory-of-evolution-reveals-about-artificial-intelligence/258829/

    • Jason Carr

      Bookmarked. Thanks for the link :)

      I agree…technology that can learn and evolve is crucial in the process. Speaking of consciousness…do you think that if we ever do figure out how to replicate a human brain in a system, that it would become self-aware? If that happens, some might consider that consciousness….depending on who you ask. I have yet to find anyone that has defined consciousness in a way that everyone can agree upon though. Great insights Jim.

  • kriya

    Because of this hierarchy we can easily approach to an artificial light harvesting antenna system.

    Hierarchy Structure

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