Everyday Einstein unravels the confusion between genes, DNA, chromosomes, genetics, and other technical terms that are thrown around in science news.
If Addy had possessed eyes, he would have rolled them. Sometimes the other nucleotides forgot that their chromosome, just like all of the others, spent most of its time as a long, stringy mess inside the nucleus.
It was only when the cell was getting ready to divide that the DNA would wind itself up into the long, cylindrical shapes that most people pictured when they thought about chromosomes. (If people thought of chromosomes at all these days.)
But Addy thought that the reason most of those nucleotides grumbled so much was because they were bored. Only about 2% of nucleotides in the entire collection of chromosomes were part of the elite collection of DNA responsible for encoding genes. Addy didn’t like to brag, but he’d been part of that elite group ever since he first joined chromosome 17.
Addy, along with about 20,000 of his nucleotide colleagues, formed one of the best genes in the cell. The purpose of their gene was to teach the cell how to build a pretty famous protein called p53. You probably read about it, it’ been in all the papers, responsible for cancer suppression and the like...a really important protein. And without Addy and his friends, it wouldn’t exist.
Whenever the cell needed more p53 protein, it would send someone over to Addy’s gene to copy down the instructions on how to make it. You might wonder why they had to copy instructions each time, well the weird thing was that the instructions were actually destroyed in the process of making the protein. Addy didn’t like to criticize how other parts of the cell worked, but he thought it was an awfully inefficient way to go about things.
Addy could still remember the first time this happened - seemed like only yesterday. There was a commotion going on somewhere down the line of DNA from where their gene started. A big molecule named RNA polymerase (though he insisted they just call him, Art) had showed up, asking for a copy of the instructions to make p53. Of course they’d been happy to oblige him.
So Art had walked down the line of nucleotides that made up the gene and made a copy of each one. This might seem like an odd way to retrieve instructions, but the fact was that Addy and the other nucleotides which made up the gene didn’t just know the instructions for making p53, they were the instructions for making p53.
For whatever reason, running a copy of their exact sequence through the cellular machinery (a process the higher-ups referred to as translation) would end up forming a protein. Addy could think of more efficient ways to make proteins, but he didn’t ask questions. He had a job to do.
So hopefully that story helped unravel some of the tangled mess of jargon used to describe DNA. To review, our friend Addy was an adenine nucleotide, one of 4 different types of nucleotides that make up DNA molecules.
Each of your cell has 46 pieces of DNA, which we call chromosomes. 23 of those come from your mother and 23 from your father. A small fraction (about 2%) of those chromosomes have the important job of encoding genes, the sequence of instructions which tell the cell how to build proteins.
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