Where Is DNA Located in the Cell? DNA Fact Sheet

By now, most of us are aware of things in our body like red blood cells and chromosomes. But what about DNA? What are DNA sequences, daughter cells, the genetic code, mutations, and cell division? Where exactly is DNA in the cell? In this article, we will fill you in on everything you need to know about DNA.

DNA is a really long molecule that contains a lot of important information. As much as we like to think that we are all different, fundamentally speaking, we are all the same. By that, I mean that we all have cells in our body that guards DNA deep within them. In fact, about 99% of the contents of each of our DNA strands are the same. In other words, we are all different because our DNA differs by 1%.

DNA is a long molecule, a string, that is made up of small little building blocks, called nucleic acids. The sequence of these nucleic acids determines pretty much everything about us, our hair and eye color, our height, weight, and many other things. These nucleic acid sequences are also called genes, which I am sure you have heard of before. These genes code for proteins that turn into both our visible as well as invisible characteristics.

The DNA molecule is really long. It contains billions of base pairs, and it is speculated to be about 3 meters in length once stretched out.

Given DNA’s importance in our lives, it is vital that it remains protected. How would you think precious things are protected best? Would you make sure they are packaged in additional containers? Would you ever wish these precious things never left and stayed put? Well, the cell is doing just that with DNA. In other words, it truly goes out of its way to make sure that nothing happens to the DNA that it carries. In fact, not only is DNA siloed deep inside the heart of each cell, it is guarded so fiercely that it never leaves the cell. So how, you may wonder at this point, does DNA manage to determine so much about us without ever leaving the depths of the cell? Let’s get into that a bit.

The DNA molecule is really long

Each cell is incredibly compartmentalized, containing several compartments that have their own unique function. Think of the inside of a cell like a very busy city with many roads and buildings. Each building is called an organelle in the cell. And just like in every organized city, buildings have purposes. The same goes for cells—each organelle has a specific function. The most important building within the cell is an organelle called the nucleus. Translated from the Latin, nucleus means “kernel” or “seed.” Translated to our cell and DNA, it means that it is the control center of the cell. Not only does it house the most precious material, it also determines the faith of each cell, its components and ultimately each person’s life.

Let’s first talk about the inside of the nucleus before we take a step outside. The interior of the nucleus is made up of DNA. It houses supercoiled DNA strands that contain a person’s genetic information, or the genome. It also houses proteins around which the DNA is supercoiled so that all of it can fit inside the nucleus in an organized and structured form. The nucleus ensures that DNA is protected from anything outside of it and keeps it intact as well as stable. The walls of a nucleus, or its membrane, is made up of an extremely selective double layer. Think of this as several double doors that make it incredibly difficult for anything to either come in or leave. The double membrane of the nucleus ensures that DNA is protected from anything potentially harmful. It is selective, however, meaning that it does let things in and out, but it is a rigorous selection process.

Let’s back up for a second. The nucleus houses the DNA that never leaves. This goes back to the cell ensuring that its most precious component does not get harmed. Instead of the DNA leaving, it gets copied, or transcribed, within the nucleus via very elegant processes. Once a copy of the DNA is made—and this is no joke because a supercoiled and dense DNA molecule has to be uncoiled and separated in order for the copy to be made as accurately as possible—it is then ready to cross the nucleus’ fine membrane and move on to other organelles, where it is used to make proteins via a process that is called translation.

You are probably thinking how all of this is pretty nifty—and you are right. Our DNA is rather protected and, just like a precious piece of paper that you never want to lose, it is copied over and over. The original is never used. Deep within the nucleus is a structure called the nucleolus, whose main responsibility is to synthesize ribosomes, or structures where RNA is made into protein.

So, how do we become who we are and develop and thrive if the material that makes us who we are, never actually leaves its location? DNA, as mentioned before, is copied into a molecule that is called RNA. This RNA is turned into proteins just outside of the nucleus—or in its front yard—within a structure called the endoplasmic reticulum on a complex machinery structure made up of ribosomes that read the RNA strand and spit out protein components. The endoplasmic reticulum is incredibly complex and it sits just outside of the nucleus.

Overall, DNA has it pretty good, if you think about it. It never leaves, it is protected, and it does not have to do particularly much other than just open itself up to being copied so that things can go on beyond the walls of the double membrane without DNA having to be around.

Laura Day
 

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