At the origin of all animals, plants, shells, or humans, there was a small, microscopic egg. For humans, this little egg is in mom’s womb. Then this one will divide and we arrive at two cells, which will remain glued to each other. Then, again, these will separate in two, and we will get 4 cells always joined. And so on, until you get to a lot of cells. Then these cells will be metamorphosed, each in a different way. Some will constitute the bones, others the heart, still others the skin, etc. So, after 9 months, we get a baby, looking almost like every human being. So, in summary, we are all like a giant puzzle made up of about 60 trillion cells. However, the metamorphosis stage produced very different cells. Those which constitute the bones are very solid, while those which make the skin, are elastic and well welded between them, those which are in our muscles are capable of shrinking and enlarging in an instant to allow us to make movements, jump, walk, run! In short, we have lots of different cells. And yet, originally, there was only one cell, only a small egg! So how can all of this work properly? How does this magic work? In each of our microscopic cells, we have a large ball, called a nucleus, much like in a peach. In this nucleus, we have a very, very long thread called DNA. This DNA contains information for all of our cells: to make what it needs or to help it get energy. This DNA, which is very long, is a bit like a cookbook … so you have recipes for everything. In our DNA, we have around 25,000 different recipes! Except that these recipes are called genes, and the recipe book, the genome.
And these genes, they allow our bones to be strong, our skin to be elastic, our brain to think, our muscles to make us move. Genes, and therefore DNA, are very important. If the information in a gene changes, it could disrupt certain organs. For example, if we erased the eggs in the pancake recipe, we could never make beautiful thin pancakes! So, we must be careful not to damage our DNA! There are a lot of things that can damage it. However, in the cells we have sort of garage owners … that is to say DNA repairers who are able to repair, for example, breaks.