HV blog

In a human body there are more than 10,000 types of nanomachines working. But there are one that is the most important for us: the ribosome. That molecule is the one that "construct" proteins from a DNA molecule. This proteins can be enzymes (useful for industry and medicine) or any other type of proteins.But this nanomachines are not like the machines we are used to see in the macroscopic universe. They are not ruled by the usual forces we know (gravity, inertia) as we are. The fact that they are a discrete number of atoms makes them to avoid the effects we know. So gravity can be considered non-existent, same for inertia or friction. But another forces are important, like thermal motion, that are really important in this scale. For example, every molecule inside a cell is supposed to interact in a single second with all of its neighbours. So they are continually being hit by another particles. That makes the structure of the molecules a really important feature.This machines works inside a water enviroment.

The inside and outside of a cell is water and without it, it would be impossible for them to work. Water creates a bounch of hard restrictions for the nanomachines working in atomic scale. It has strong interactions with electronic charges, zones rich in nitrogen and oxygen. This is called hidrofilic effect. However, zones rich in carbon don`t form bonds with water. That is a really important characteristic that defines most of the molecules.There are four basic molecules in every organism. Proteins, nucleic acids, polysaccharides and lipids.Most of the bionanomachines are composed of protein. They can be really rigid or not rigid at all. They can be part of structures. Enzimes are very small proteins. So there is a bounch of possibilities.The typical sice is from 200 to 500 aminoacids. This aminoacids associate themselves in chains and form variable spacial forms. The two most stable are the a-helix and the B-sheet. There are 20 different aminoacids. They combined in the proper order forms a proteine. Some of these amino acids are "special" and they can be used to stop the production. The amino acids used to start are still being studied. Other amino acids are used to another specialized tasks. There are, however, some proteins larger than 500. In some bacterias they can contain more than 2000, but when they are too big they become unstable and the errors produced during the transcription can be fatal.So protenis are really versatile, that is why bionanotechnology try to use them to construct many different molecules for many different purposes.This proteins are coded from the information stored in the nucleic acids. They are the data storage of nature. There are two types of them: DNA (desoxyribonuycleic acid) and RNA (ribonucleic acid). There are 4 bases to construct DNA, adenine, guanine, cytosine and thymine. The same are used to RNA, but instead thymine uracil is used. It is almost the same molecule, but with some changes. In each base there are 2 bits stored. There are 4 possibilities, one bit stores 2 of them, so 2 are needed. Although this nucleicacids are to store information they can be used to another purposes because of the easy predictable, strong and large structures they can form. For example, the robosoms are mostly formed by RNA.

Another molecule very common is the lipid. It is a molecule with two parts: one hydrophobic and another one hydrophilic. This feature makes them to associate in a water environment creating large molecules that can be membranes or globules. In this membranes there are inserted some other molecules that give them some special skills. Lipids are impermeable to big molecules, but permeable to the small ones.

The last molecules are the polysaccharides. This is the most versatile molecule of organisms. It can combine itself with many other molecules getting many different properties. Can be liquid like mucus or really hard like nails.

Evolution has been crucial in all this development. It is the most important and fine test to any machine. It selects the accuraced changes and kills everything not enough specialiced or useless. It provides changes that are impossible by intelligent design. Evolution places strong constraints to any change. That is why it favores modification over innovation. The nanomachines inside our body, for example, can't work in another environments outside ourselves. But because of this they have improved and have many methods to remain. They have redundancy implemented to avoid errors. In every duplication of a nanomachine, molecule or whatever errors can appear. If they appear in nucleic acids they are called mutations. This changes can be bad, meaning they can kill the new child (in an organism) or make non useful the molecule. But sometimes they can improve the function of that individual and then evolution will reward it so that change will remain in its descendants. Because all this changes are in the same enviroment the molecules working there are always in the same conditions, without them the nanomachines are not working any longer.