Find out what SILENT MUTATIONS are

The genetic mutations They are the stable changes that occur in the DNA of our cells, but these changes can be of different types. In a previous lesson from a TEACHER we already addressed the types of genetic mutations but in this lesson we will focus on silent mutations, What are silent mutations? Silent mutations, are they important to us? If you want to know more about silent mutations, keep reading!

The genetic mutations are all those stable changes that occur in the genetic material of an individual, that is, in its DNA. In a previous lesson from a TEACHER titled Types of genetic mutations We review the different types of mutations that can affect DNA and one of them is silent or synonymous mutations. Silent mutations are stable changes in the DNA sequence that do not result in a change in the amino acid produced by said sequence, so it is considered that this type of mutations do not produce a change, that is, they are "hidden" or are silent.

What is DNA and how does the genetic code work

The DNAis written or encoded with a code of four letters or nitrogenous bases: A, T, G, C. Some organelles of the cell, the ribosomes, are in charge of reading this genetic code and putting amino acids one after the other. The set of many amino acids together make a protein, which is a large molecule with many functions in the body. Ribosomes read the letters of the genetic code in groups of three at a time. These groups are called codons or nucleotide triplets. In the human species there are 61 codons and 20 different amino acids, so each of the codons corresponds to an amino acid, but there are several codons that code for the same amino acid. In this way, when the ribosome reads the UUA sequence, it adds a leucine while if it reads the AGA codon, puts in the chain of amino acids that is making an arginine but, when it reads CGA it also puts a arginine.

Therefore, a sequence mutation of amino acids in which the AGA codon is changed, which is translated into "arginine" by the codon CGA, which also codes for "arginine", will not produce an amino acid change and is therefore said to be a silent mutation. Researchers currently prefer the term synonymous as it better describes its effect: it changes one codon for another which means the same for the ribosonome, that is, they are synonymous codons. Instead, it is not clear if this mutation is really silent or has something to say, that is, some effect on the protein generated by the ribosome.

And thatSilent mutations do not cause an amino acid change which is added to the chain, and therefore does not modify the composition of the protein in formation, at first it was thought that this type of mutations had no effects. In the 1980s, researchers began to realize that silent mutations did influence protein production, but they didn't know exactly how either. Recent research has linked silent mutations with different alterations. One of them is related to changes in the three-dimensional structure of protein. Changes is the three-dimensional structure of the protein, that is, the appearance it has in space (more rounded, with a gap there or a gap here) can make it more functional, less functional, or totally non-functional.

In other research, on the other hand, silent mutations have been linked to a speed of transcription slower. It seems that ribosomes have a harder time decoding the rare codons, adding the selected amino acid, forming the corresponding protein and giving it a correct shape.

In other species it has even been related to overexpression of genes, that is to say, with which an abnormally high amount of a protein is produced. The overexpression of certain proteins could also have negative effects on the body and is the cause of some very common human diseases.

It is currently being studied as silent mutations are related to more than fifty types of diseases among which are different types of cancers wave cystic fibrosis. In fact, the existence of silent mutations in the toxic elimination mechanisms of some types of cancer cells has been demonstrated. Those silent mutations make these malignant cells shed the drug and become resistant. whereas cancer cells without that type of silent mutation are sensitive to that treatment.

In nature it is observed that, depending on the species, the cell prefers to use one codon to others to code for a certain amino acid. There was rare codons and frequent codons, and the researchers did not know why the preferred codons were chosen. This still remains a mystery but, it appears that silent mutations that change frequent codons for codons Rare diseases can increase the chances of suffering from certain diseases or that they are more resistant to treatments pharmacological.

The truth is that one thing is for sure: silent mutations are not as silent as they seemed in the beginning and they do have effects on the expression of proteins and even on the appearance of very important diseases today.