Raphaël, 8: "What are chromosomes for?"

Our body is made up of a collection of cells. Inside each cell is a small "sac" called the cell nucleus. It contains the chromosomes that physically carry our genetic information.

Giacomo Cavalli, University of Montpellier and Frédéric Bantignies, University of Montpellier

This information is inscribed in the deoxyribonucleic acid molecule: DNA. All the genetic material carried by the chromosomes constitutes the "genome", specific to each living species.

It is within chromosomes that we find genes, small portions of chromosomes each carrying the information needed to synthesize a protein, an essential component of cell structure and function.

Initially, parents pass on their chromosomes to their children at fertilization, when the sex cells meet. In humans, in the very first egg cell, there will be a total of 46 chromosomes. They function in pairs, with 23 chromosomes coming from the mother and 23 from the father. In this way, we inherit the "genetic heritage" of both our parents equally and in full.

Throughout our lives, our cells divide to multiply, enabling us to grow and stay healthy. Chromosomes maintain, reproduce and transmit all genetic information from cell to cell, as individuals develop and throughout their lives.

In humans, the 46 chromosomes contain around 2 meters of DNA. If we were to put the DNA of all the cells in an adult organism end-to-end, we could travel 500 times the distance between the earth and the sun!

The human genome contains around 23,000 genes, which is only a very small part of its length. The rest of the genome contains vast regions which are located around genes and serve to regulate them, as well as isolating genes from neighboring regions so that each gene can be regulated independently. In fact, all the genes in all our cells must not be activated at the same time. This is what makes your heart cells different from your skin cells, for example.

Giacomo Cavalli, CNRS Research Director, University of Montpellier and Frédéric Bantignies, CNRS Researcher, University of Montpellier

This article is republished from The Conversation under a Creative Commons license. Read theoriginal article.