At the molecular level we are very simple, since all living beings that populate the Earth are made up of a small number of molecules. In fact,living matter consists mainly of long molecules in which a certain pattern repeats itself over and over again, sometimes with small variations. In addition, some of them fold in an elaborate, complex and extremely precise way. This allows them to act as catalysts, speeding up the speed of chemical reactions. These catalysts are called enzymes.
In essence, we can group the molecules of life into four groups:sugars(that provide energy),lipids(whose function is mainly structural, such as the formation of membranes),protein(which provide the machinery that allows cell function) andnucleic acids(that carry the information).
It is surprising how extraordinarily selective life has proven to be in choosing molecules. For example, from the enormous number ofamino acidspossible uses only 20. And if a typical protein contains on the order of a hundred amino acids, then we could build at least 20100, a number vastly greater than the number of atoms in our galaxy. However, most living organisms use less than 100,000 types of protein.
One of the basic properties of life is its ability to reproduce itself. Despite all the diversity that we observe, at the molecular level the reproduction of all organisms follows the same plan: a certain type of polymer – anucleic acid– shaped like a double helix, theADN, governs the process through a “mold” mechanism.
Information links
The links with which DNA is built are called nucleotides , and they are composed of only a sugar, a phosphate and one of four possible carbohydrates called nitrogenous bases. Many could have been used, but life, again, has been selective and only uses adenine (A), guanine (G), cytosine (C) and thymine (T) . They are the four letters of our genetic code .
DNA is where it is kept and who transmits biological information. But there is another type of nucleic acid, RNA , essential for the survival of the individual: it is mainly responsible for articulating the instructions contained in DNA, such as protein synthesis.
Explaining where this entire organization came from is one of the great challenges of the 21st century. To get an idea of our ignorance: we have no idea how, from the basic building blocks of life – such as amino acids or the bases of nucleic acids – RNA, DNA, appeared. Nor, of course, how the first cell appeared.
Sex
Ferns today are basically the same as they were hundreds of millions of years ago. The same occurs in the case of xifosuros? Also known as the Moluccan pans ?, sea turtles or crocodiles. Although there are species that have evolved rapidly. An example is ours, which is accompanied by the horse or the elephant.
Essentially, species evolve because “errors” occur in the copy of the base macromolecule of life, DNA. However, if evolution depended solely on mutations it would be boringly slow. But most living things discovered between 1.7 and 1.5 billion years ago a wonderful mechanism capable of producing a great variety of genetic combinations in each generation: sex .
In addition to moving the world, sex has been a source of diversity, since with sexual reproduction the genes of the parents combine and recombine in each generation, producing a unique genetic configuration. Sex shuffles the genome cards and allows testing a multitude of combinations that would have taken millions of years just by mutation. Of course it has its drawbacks. The biggest is the loss of immortality. If we reproduced asexually, with each division we would produce clones of ourselves. Except for the unexpected and rare mutations, we would be like bacteria, which remain practically as they were billions of years ago. Sex makes us mortal.
