Deoxyribonucleic acid

DNA.

It is a complex code of our genetic material that can predict most of who we are, particularly physical characteristics (emotional, personality and mental characteristics are more "nurture" than "nature").

DNA sample

So, what is it's physical structure?

This is a structure called a "double helix". A double helix is a pair of parallel helices intertwined about a common axis. Great...but what is a helix? That is a curve that lies on the surface of a cylinder or a cone and cuts the element at a constant angle. Still confused? The way I think about it is a ladder that is wrapped up into a coil. Here is an artists rendering of a piece of DNA.

See what I mean? So what is it's purpose?

Deoxyribonucleic acid is the encoding for our genetic make up that is in "long-term storage". This is done through nucleotides. These nucleotides are made up of a phosphate group, a sugar group and a nitrogen base. There are four nitrogen bases: adenine, guanine, thymine and cytosine. Each of these has a pair that they are matched with. Adenine and guanine are matched up, while thymine and cytosine are matched up. The way that these bases are arranged determines how each of a person's genes are expressed.

A comparable way of thinking about it is with letters: letters (base pairs) arranged in a certain way express a certain word (i.e.: a specific gene). The words that are written out to form sentences and paragraphs and stories express large ideas (i.e.: the specific genes that are expressed make up the person).

The sugar in DNA is called deoxyribose (thus the name, deoxyribonucleic acid: deoxyribose sugar + nucleotides). Meanwhile, for RNA (ribonucleic acid), the sugar is ribose. Now, what is RNA?

RNA is similar to DNA with a few exceptions. This also codes for genetic information using a phosphate group, a sugar group (ribose) and a nitrogen base to form nucleotides. The nucleotides in RNA are the same as in DNA with one exception: uracil replaces thymine. This genetic code is also single-stranded and generally shorter than DNA. It can be formed from a preexisting RNA strand of from a strand of DNA.

It is strange to think that this structure is inside every living cell of my body. When I look at it and have studied it in the past, it is studied in a context that makes it larger than life (at least, larger than it occurs in the body). It is hard for me to think of it in the size that it exists and that it is in every part of me and that it is vital to my existence. Something so small is so important -- and that is strange to think about, but amazing at the same time. My genetic material is encoded in something so small that, not only is it inside a cell, but it fits into the nucleus of the cell (as a general location). It is simply amazing how this was all constructed to make us individuals and separate from one another.