Found in Translation
By Lance Gritton M.A. Ed
DNA! DNA! I’m sick about hearing about DNA. Did you know that in many court cases, if you don’t have DNA evidence, the whole trial could be in doubt? Prosecutors have a name for this. It’s called the CSI effect named after the popular TV series. Jurors expect all trials to have some black and white evidence in the form of DNA. While DNA has the ability to put a person at a crime (or not) scene, and it also contains all the information to make an organism. Because of some cool biochemistry we won’t get into here it is very stable and can survive in the right conditions for millennia It does have one weakness; it is dead in the water without some help.
Ok, this looks like the beginning of a two part (or more) column on nucleic acids. DNA stands for deoxy-ribo-nucleic-acid and is found in all organisms. In fact when we talk about what is considered living, we say it eats, grows, gives off waste and reproduces. Well under those conditions, fire is a living organism. It eats its fuel, grows, gives off CO2 and can reproduce when it jumps to another tree or when we put a branch or marshmallow into it. But the one thing it does not have is the ability to pass on traits to the next generation. As far as we know, only DNA can do that, and fire is lacking that genetic information.
DNA is like a depository of information. It holds the information but can’t do anything with it. It’s like knowing all the recipes ever made, but it can’t even boil water. DNA is what is in all of our cells. It is contained in the nucleus of our cells. The most fundamental division of life on Terra is cells that have a nucleus, called Eukaryotes (that means little kernel) and Prokaryotes, the bacteria (means before there was a kernel). Auf Deutch , kernel is a nucleus, so those with a cell kernel have a nucleus, and those without are bacteria. But bacteria still have DNA.
DNA is stored in the form a chromosomes. Chromosome means a thing that can be stained with dyes; (like Chodacrome ala Paul Simon). The nucleus and the chromosomes were some of the first things that our early scientists could see in their primitive microscopes. We have 23 pairs of chromosomes; one set from mom and one set from dad. Bacteria have only one chromosome. The DNA is wound up like a rubber band on a model airplane. It’s twisted around itself, and then knotted about itself and then wrapped around a protein called a histone. You see DNA is negatively charged due to its phosphate backbone (I’m glad I know my ions). Histones are positively charged and keep the DNA wrapped up in the form of a chromosome.
OK so it’s all wrapped up to protect the information that makes an organism what it is. It is also double sided to help protect the information as well in the famous form of the double helix; a kind of a spiral staircase with the information contained in the steps.
Wow, that’s a lot to absorb, but who would have thought that biochemistry and cellular biology could be so complicated? OK, DNA has all of that information tightly coiled up in the form of a chromosome, but somehow that data must get into the cell to get stuff done. And as George Carlin said, you can’t do stuff without things, and you need things to do stuff. (OK he really said something LIKE that but it is a family newspaper). Regardless, we need to do stuff, or rather our cells do. DNA in this form is much like a locked up filing cabinet; all of our information is safe but not very useful.
What our cells need is a personal assistant to unlock our files and access them. This PA is in the form of a cousin of DNA called RNA or ribo-nucleic-acid. RNA is single stranded and has one different base than DNA, but it can do what DNA does in the form of storing information, and it can behave like an enzyme, a protein that does stuff (Carlin again) but does neither as well as DNA or enzymes can d0, but more on that later.
A special enzyme called helicase (all enzymes end in –ase). Helicase unwinds the DNA from the histones and itself, and opens the DNA up so it can be “read” by special enzymes called polymerases. Poly means many so a polymerase makes many things via an enzyme (rememberase is an enzyme I need more and more of). The process of reading the language of our cells is called transcription; just like a scribe might write down the words of a Lord or King; transcription takes the information and does stuff with it. (I miss you George Carlin). But to be useful it needs to be translated into non-king-speakese, and that’s what we’ll talk about next week. It’s called anticipa………