DNA: A biological macromolecule at the basis of the formation of chromosomes and genes

Par malumiereetmonsalut Le 29/04/2025 à 09:06 0

Health

Chromosomes and genes are a set of fragments which constitute a DNA which is itself the basis of their formation. Image: genetique-medicale.fr

Explanation/Also known as deoxyribonucleic acid, DNA is a long thread-shaped molecule, which constitutes in some way, the tail of chromosomes composed of a succession of nucleotides or constituent elements of a nucleic acid molecule attached to each other by bonds.

We cannot talk about chromosomes and genes without talking about DNA. Chromosomes and genes are a set of fragments which constitute a DNA which is itself the basis of their formation, and which contains all the information necessary for the proper functioning and development of our body.

According to a GenkBank database, designed to provide and encourage access to the most comprehensive information on DNA sequences, "the DNA of chromosome number 7, for example, is made up of approximately 159 million nucleotides, and contains more than 900 genes."

If DNA constitutes our chromosomes, or if our chromosomes are made up of DNA, genes are a small portion of DNA also present in duplicate in human cells; one of paternal origin, and another of maternal origin.

The nucleus of cells, which plays the role of central unit, has within it all the necessary information. It is the paired genes called alleles that tell each cell its role in the body. Cells are therefore not organs in which anyone does anything, but where each organ has a well-defined role.

It is on the orders of genes that cells produce tens of thousands of proteins, including those of the brain which produce Myelin, which has a role in protecting neurons, the cells of our eyes which produce proteins which help us to see, and those which are involved in defining the colour of the eyes, or the shape of the face. Every human being has a set of genes called a genome that are unique to them, and which differentiate them from other people. But for genes to play their role, DNA is first required, just like cells need information from genes to make proteins.

Also read: Genetics or familial deseases: What you need to know

Note that the paternity tests sometimes necessary to resolve disputes in civil and criminal matters, among others, consist of comparing the DNA of two samples, or of verifying the parentage link between the father and the child when those who use these tests do not want to be satisfied with the other traits of resemblance which are very often fragrant.

The advantage of legal DNA testing is that it is impossible for the results obtained to be false, unless there is misinformation which can only be the result generated by individuals who do not want the truth to be revealed. “The support of genetic information (DNA) of every human being is made up of structural units called nucleotides. Each type of nucleotide is made up of three units: a nitrogen base, a sugar, and a phosphate group. There are four types of nucleotides forming DNA: Ademine (A) which participates in the formation of Adenosine (where Ademine is associated with a ribose)which enters into the formation of nucleic acids (DNA and RNA); Guanine (G) which participates in the formation of Guonosine (where guanine is associated with a ribose or sugar with five carbon atoms [Note that the carbon atom forms the structure of all organic molecules in living beings, in association with oxygen, nitrogen, phosphate and hydrogen. The carbon atom represents 18.5% of the mass of the human body]) which is notably involved in the formation of nucleic acids; Tymine (T) which participates in the formation of tymidine (where thymine is associated with a ribose) which enters in particular in the composition of DNA; and Cytosine (C) which is a nitrogenous base which is used in the formation of nucleic acids.

"The two strands of DNA or chains of the double helix or curve of the DNA molecule, are linked together by nucleotides which form complementary pairs: Ademine with Tymine (A-T or T-A) and Guanine with Cytosine (G-C or C-G) (…) DNA serves as a transmission of genetic information which, however, cannot be read directly by the cell." DNA must undergo transcription or translation so that the cell can, among other things, produce proteins. Indeed, “when the cell has to make proteins, she will first “photocopy” the recipe contained in the corresponding gene. This copy is made by a protein called RNA polymerase. The copy, called Messenger RNA, will be transmitted to the ribosomes which are large molecular complexes which, in addition to being machines for manufacturing proteins, also have the capacity to decipher or read the instructions contained in the messenger RNA. Everything is well organized and a small malfunction is enough to handicap a system where interdependencies are essential in the proper functioning of the human organism.

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