Human chromosomes
Interesting facts from the world of medicine sometimes give us surprising surprises. For example, do you know what chromosomes are and how they affect a person?
We propose to deal with this question in order to dot all the i’s once and for all.
Looking at family photos, you might have noticed that the members of the same kinship resemble each other: children – on parents, parents – on grandparents. This resemblance is passed on from generation to generation through the amazing mechanisms of genetic heredity.
All living organisms, from single-celled algae to African elephants, have chromosomes in the cell nucleus, thin, long strands that can only be viewed under an electron microscope.
Chromosomes (Greek χρῶμα – color and σῶμα – body) are nucleoprotein structures in the cell nucleus in which most of the hereditary information (genes) is concentrated. They are designed to store this information, implement it and transmit it.
How many chromosomes a person has
At the end of the 19th century scientists discovered that the number of chromosomes in different species is not the same.
For example, a pea has 14 chromosomes, a rat has 42, and a human has 46 (that is, 23 pairs). Hence, it is tempting to conclude that the more there are, the more complex the creature that possesses them. However, in reality this is not the case.
Of the 23 pairs of human chromosomes, 22 pairs are autosomes and one pair is a gonosome (sex chromosomes). The sexes have morphological and structural (gene composition) differences.
In a female organism, a pair of gonosomes contains two X chromosomes (XX pair), while a male organism has one X and one Y chromosome each (XY pair).
It is on what will be the composition of the twenty-third pair of chromosomes (XX or XY), depends on the sex of the unborn child. This is determined by fertilization and fusion of female and male sex cells.
This fact may seem strange, but by the number of chromosomes humans are inferior to many animals. For example, some poor goat has 60 chromosomes, while a snail has 80.
Chromosomes are made up of a protein and a DNA (deoxyribonucleic acid) molecule, which looks like a double helix. Each cell contains about 2 meters of DNA, and our body cells contain about 100 billion kilometers of DNA.
It is an interesting fact that if there is an extra chromosome or if at least one of the 46 chromosomes is missing, a human has a mutation and serious deviations in development (Down’s disease, etc.).
It is in connection with this scientific fact that an “intelligent” insult spread among the people: “Do you have an extra chromosome?”
Now you know general information about the principles of heredity. In general, this topic is very interesting, although extremely complex.
By the way, you may also be interested in the article about why twins look alike.