How Many Chromosomes are Found in the Human Body

Introduction

Each cell's nucleus contains chromosomes, which are structures that resemble threads and contain the DNA molecule. Each chromosome is made of DNA that has been tightly wound around proteins called histones numerous times to support its structure. Genetic diversity is greatly influenced by chromosomal recombination during meiosis and subsequent sexual reproduction. The cell might experience mitotic catastrophe if these structures are mishandled through procedures known as chromosomal instability and translocation. Normally, this will cause the cell to begin the process of apoptosis, which will cause it to die on its own, but occasionally, mutations in the cell prevent this from happening and thereby advance cancer.

In eukaryotes, the number of chromosomes varies greatly. Chromosomes can actually join together or separate, creating new karyotypes. Chromosomes can also be artificially fused. For instance, the cells were still viable despite having only slightly slower growth rates when the 16 chromosomes were fused into one large chromosome.

Chromosome

The word "chromosome" derives from the Greek words "chroma," "colour," and "soma," which refer to the strong staining that certain dyes have on them. The phrase was first used by the German anatomist Heinrich Wilhelm Waldeyer to refer to the concept of chromatin, which Walther Flemming, the discoverer of cell division, had previously introduced. The thread-like chromosomes that carry genetic information from cell to cell are made of proteins and a single DNA molecule. Chromosomes are found in the nucleus of cells in both plants and animals, including humans.

Chromosomes are typically only visible under a light microscope during the metaphase of cell division, when all of the chromosomes are aligned in the centre of the cell in their condensed form. Prior to this, each chromosome undergoes a process known as chromosome duplication (S phase), during which a centromere connects both copies, forming either the X-shaped structure shown above (if the centromere is situated equatorially) or a two-arm structure (if it is situated distally), depending on where it is situated. Sister chromatids are now the name given to the combined copies. The X-shaped structure during metaphase is known as a metaphase chromosome, which is highly condensed and therefore the easiest to recognise and study. Chromosomes are most compacted in animal cells during the chromosome segregation process known as anaphase.

History

German scientists Schleiden, Virchow, and Bütschli were among the first to recognise the structures we now call chromosomes.

• Theodor Boveri made significant contributions to the understanding that chromosomes are the carriers of heredity through a series of experiments that began in the middle of the 1880s. These contributions included the concepts of "chromosome continuity" and "chromosome individuality."

• Boveri was able to test and validate Wilhelm Roux's theory that each chromosome carries a unique genetic configuration. Boveri was able to make the connection between the laws of inheritance and the behaviour of the chromosomes thanks to the rediscovery of Gregor Mendel's earlier work at the beginning of the 20th century. Edmund Beecher Wilson, Nettie Stevens, Walter Sutton, and Theophilus Painter were all influenced by Boveri; Wilson, Stevens, and Painter actually collaborated with him. Boveri had an impact on two generations of American cytologists.

• Wilson connected the independent research of Boveri and Sutton, who were both born around 1902, by referring to the chromosome theory of inheritance as the "Boveri-Sutton chromosome theory" (the names are occasionally reversed) in his renowned textbook The Cell in Development and Heredity.

• Some well-known geneticists, including T.H. Morgan, Richard Goldschmidt, William Bateson, and Wilhelm Johannsen, all of whom had a rather dogmatic outlook, vigorously disputed the theory, according to Ernst Mayr. Finally, chromosome maps produced in Morgan's own lab provided conclusive evidence.

• Theophilus Painter published a report on the number of chromosomes in humans in 1923. He discovered 48 chromosomes by counting 24 pairs of them under the microscope. His error was repeated by others, and it wasn't until 1956 that cytogeneticist Joe Hin Tjio, who was born in Indonesia, discovered the correct number, 46.

Chromosomes in Humans

Each of a human cell's 23 pairs of chromosomes contains a total of 46 chromosomes (22 pairs of autosomes and one pair of sex chromosomes). The mitochondrial genome is also present in many hundreds of additional copies in human cells. The human genome's sequencing has revealed a wealth of knowledge about each chromosome. Humans have two different types of chromosomes: autosomes (body chromosome(s)) and allosomes (sex chromosome(s)). The sex chromosomes allow for the transmission of specific genetic traits that are connected to a person's sex. The remaining genetic and hereditary information is found on the autosomes.

Human Genome Project

The Human Genome Project was an international scientific research endeavour whose objectives were to identify the base pairs that make up human DNA and to recognise, map, and sequence every gene in the human genome from both a physical and functional perspective. It began in 1990, and it was finished in 2003. The Human Genome Project (HGP), a 13-year undertaking overseen by the National Institutes of Health (NIH) and the U.S. Department of Energy (DOE), was finished in 2003. Along with contributions from China, France, Germany, Japan, and other nations, the Wellcome Trust (UK), which later developed into a significant partner in the HGP's early years, made additional contributions.

The project goals were to -

• identify each of the roughly 20,500 genes present in human DNA,

• determine the 3 billion base pairs that make up human DNA's sequence,

• maintain databases with this data,

• enhance data analysis tools,

• transfer relevant technologies to industry, and

• Discuss any potential ELSI (ethical, legal, and social issues) with the project.

Conclusion

The human body comprises 23 pairs of chromosomes (46 chromosomes), out of which 22 pairs are autosomes, which define the structural and functional features of the person, while the one pair known as the "sex chromosome" decides the sex or gender of a person. Along with this, cells also have extra chromosomal bodies from mitochondria and golgi bodies.