Genes are parts of DNA. These parts contain the information needed to make a protein that has a specific role in the body. Chromosomes are one of the cell molecules that contain genes.

What is a chromosome?

Chromosomes are thread-like molecules located inside the nucleus of human cells, and each chromosome consists of a protein that binds to a single molecule of deoxyribonucleic acid (DNA).

The chromosome is passed from parents to children; To pass on DNA to offspring, which in turn contains some information that makes each individual unique.

types of chromosomes

• Autosomal (autosomal) chromosome: It represents all the chromosomes of cells in the body, except for the sex chromosomes (X and Y), and each somatic cell contains 44 chromosomes.
• Sex chromosome (gametes): They include the X chromosome and the Y chromosome, and sex cells contain only 23 chromosomes (22 autosomes and one sex chromosome); Because sex cells go through the stages of cell division.

When fertilization occurs, the gametes fuse together; to have 46 chromosomes per cell.

How many chromosomes are in a human?

Humans have 46 chromosomes, and they are organized into 23 homologous pairs. The chromosomes of each pair are identical in size to each other, and each pair has the same centromere position (with the slight exception of the X and Y chromosomes).

Human cells are also binary in number (2n); Which means that most of their chromosomes come in identical sets known as homologous pairs.

As for the sperms and eggs, they are haploid (1n); That is, it contains only one homologous chromosome from each pair, and when a fusion occurs between the sperm and the egg, their genetic material unites; To form a complete diploid (2n) set of chromosomes.

What is the function of chromosomes?

The most important function of a chromosome is that it carries and keeps DNA tightly wrapped around spool-like proteins called histones, which help reduce the size of very long (up to 6 feet) DNA molecules.

For an organism to grow and function properly, cells must constantly divide; To produce new cells to replace old, damaged cells. It is necessary during cell division that the DNA remains intact and evenly distributed among cells, which is what chromosomes help with.

The chromosome plays an essential part in the accurate transcription and distribution of DNA in dividing cells, but sometimes errors can occur, which can lead to changes in the number or structure of the chromosome in new cells, and this can lead to serious health problems.

For example, some types of leukemia and some other types of cancer are caused by damage to some chromosomes, and people with Down syndrome have three copies of chromosome 21, instead of the two copies found in other healthy people.

Chromosomes and pregnancy

About 70 percent or more of miscarriages occur in the first trimester of pregnancy; Because there is a genetic defect during the formation of the fetus, and most likely the genetic defect is caused by:

• The presence of an abnormality or defect in the chromosomes from either one of the parents or both, and it can be detected by performing a chromosomal analysis of the couple.
• A defect in the genes that has been inherited to the fetus, and can be detected by DNA analysis during pregnancy.
• External causes, such as: exposure to radiation or taking some medications, which in turn leads to genetic mutations and genetic defects.

As a result, in most cases a miscarriage occurs, but in some rare cases the fetus may complete until the birth stage, but it is born with a genetic defect, and it may live for limited periods, and during these periods it may have some birth defects or disabilities, such as those with Down syndrome.