Mary Allen
DNA is a long, very thin thread. It is found in every single cell of a living being. Often it is in the cell nucleus. There in the DNA is stored how the living being is structured and functions. DNA is an abbreviation for a long chemical name.
You can think of DNA as a kind of book that contains the building instructions for making every part of a living thing, like muscles or spit. In addition, the DNA also tells when and where the individual parts are to be manufactured.
How is DNA structured?
DNA is made up of a few individual parts. You can think of it like a twisted rope ladder. On the outside, it has two strands that twist around each other like a screw and to which the “rungs” of the ladder are attached. The rungs contain the actual information, they are called “bases”. There are four different types of them.
You could say that the bases are the letters of the building instructions. Always three bases together form something like a word. If you always combine four bases in packs of three, you can form many different “words” to write the building instructions with.
Where in a living being is the DNA?
In bacteria, the DNA is a simple ring: as if the ends of the twisted rope ladder were knotted together to form a circle. In them, this ring simply floats inside the individual cell that bacteria are made of. Animals and plants are made up of many cells, and almost every cell contains DNA. In them, the DNA swims in a separate area of the cell, the cell nucleus. In every cell, there is the instruction to build and control a whole living being of this kind.
In humans, the tiny rope ladder of DNA we have in every cell is almost two meters long. In order for it to fit into the cell nucleus, the DNA has to be packed very small. In humans, it is divided into forty-six pieces called chromosomes. In each of the chromosomes, the DNA is coiled up in an intricate way so that it ends up being packed tightly. When the information in the DNA is needed, a small piece of DNA is unpacked, and small machines, the proteins, read the information and other small machines then repackage the DNA. Other living beings can have more or fewer chromosomes.
Cells divide to multiply. To do this, the DNA must be doubled beforehand so that the two new cells contain the same amount of DNA as the single cell before. During division, the chromosomes are distributed evenly between the two new cells. If something goes wrong in certain cells, this can lead to diseases such as Down syndrome.