The chromosomes, apart from the sex chromosomes, are known as autosomes of an organism. The number of chromosomes varies from one organism to others. In humans, there is a total of 46 chromosomes or in pair of 23. Out of these, 2 are sex chromosome (XX or XY), and 44 are autosomes.
Mice have in all 40 chromosomes, out of which 38 are autosomes, and 2 are sex chromosomes. Abnormalities in the chromosomes (autosomes or sex chromosomes) results in the retardation in growth of an organism or delay in development.
We defined living organisms by the presence of the living cells in them, and it can be multicellular or unicellular. But ‘cell’ is the most fundamental unit of a living organism. The cell has many organelles which perform their specific function to make the bodywork properly. Among all the organelles, the nucleus is the most vital or essential part of the cell.
The nucleus contains the thread-like structure known as chromosome, which includes the genetic information and is transferred from one organism to other of the same species. Each of the chromosomes is composed of the tightly packed DNA, that is coiled around the histones protein.
Although the location and structure of a chromosome may vary among prokaryotes, eukaryotes and viruses, like in prokaryotic cells the chromosome consist of DNA, while non-living viruses the chromosome may consist of either RNA or DNA, in eukaryotes, the chromosomes are enclosed within a membrane-bound nucleus. It also has RNA along with DNA.
With all such information, at this moment we will be highlighting the points that differentiate the autosomes and sex chromosomes, also known as allosomes. We will also provide a brief description of them.
Content: Autosomes Vs Sex Chromosomes
Comparison Chart
| Basis for Comparison | Autosomes | Chromosomes |
|---|---|---|
| Meaning | Such a pair of chromosomes that regulate the somatic characters of the body are known as autosomes. | The pair of chromosomes that determines the sex of an organism, as they regulate the sex-linked traits. |
| Labelled as | They are named or numbered from 1 to 22. | These are recognized by the letters as XO, XY, ZW and ZO. |
| Other features | The maximum number of chromosomes in our genome are the autosomes. | There are a few numbers of sex chromosomes in our genome. |
| Autosomes (22 pairs) are homologous in humans. | Male sex chromosomes (XY) are non-homologous, while female sex chromosomes (XX) are homologous. | |
| In autosomes the centromere position is identical. | In sex chromosomes the centromere position os non-identical. |
|
| It proves the Mendelian inheritance. | It shows Non-Mendelian inheritance. | |
| The number of genes carried by autosomes varies from 200 to 2000. | The Y chromosomes contain only a few genes, while X chromosome has more than 300 genes. |
Definition of Autosomes
The non-sex chromosomes present in organisms are the autosomes. In humans, there are 22 sets of autosomes; they are labelled or referred numerically from 1 to 22, like chromosome 1, chromosomes 2, chromosomes 3, etc. These are labelled according to their shape, size and other properties.
Except for the sex-linked traits, autosomes are known for regulating all other inheritance of an organism’s characteristics. It means they (autosomes) are responsible for transferring the genetic information from parents to their offspring. In the body, there are numerous cells, and each cell has 22 pairs of autosomes.
The chromosomes in each pair are of the same length, and even the centromere is placed in the same location. During mitosis, the chromosomes double themselves and then transferred to the daughter cells. Hence, the new daughter cells will receive a full complete copy chromosome, containing the genetic information of their parent cell.
Though autosomes variates from allosomes or sex chromosomes, there are certain chromosomes which determines the gender (male/female). Like, the chromosomes 17 has the gene SOX9, that activates TDF transcription factor, this is essential in determining the male sex as this factor is encoded by the SRY gene found on the Y chromosome. Female offspring are produced by the mutation on SOX9 gene in humans.
Definition of Sex Chromosomes
Such chromosomes that play a vital role in determining the gender or sex of humans or other species of animals are known as sex chromosome. These are also known as allosomes. These are named ‘X’ and ‘Y’ by scientists.
In humans out of the 23 pairs of chromosomes, one pair is sex chromosomes, and other 22 pairs are the autosomes. The one with the ‘XX’ pair of chromosomes is the female while the individual having ‘XY’ pair of the chromosome is the male.
The chromosome has two arms, the ‘p’ arm and the ‘q’ arm. In the case of sex chromosomes, the ‘Y’ chromosome consists of one very long arm and other very short arms. In the case of ‘X’ chromosomes, which is similar to the large autosomal chromosome has one long and one short arm.
Key Differences Between Autosomes and Sex Chromosomes
Given below are the critical points to understand the difference between the autosomes and sex chromosomes:
- The pair of chromosomes that regulate the somatic characters of the body are known as autosomes, whereas the pair of chromosomes that determines the sex of an organism, as they regulate the sex-linked traits are known as sex chromosomes or allosomes.
- Autosomes are named or numbered from 1 to 22, while sex chromosomes are recognized by the letters as XO, XY, ZW and ZO.
- The maximum number of chromosomes in our genome are the autosomes, and there are a few numbers of sex chromosomes in our genome.
- Autosomes (22 pairs) are homologous in humans, whereas male sex chromosomes (XY) are non-homologous, while female sex chromosomes (XX) are homologous.
- In autosomes the centromere position is identical but in sex chromosomes the centromere position os non-identical.
- Autosomes prove the Mendelian inheritance and sex chromosomes show Non-Mendelian inheritance.
- The number of genes carried by autosomes varies from 200 to 2000, but in case of sex chromosomes, the Y chromosomes contain only a few genes, while X chromosome has more than 300 genes.
Conclusion
In this context, we studied chromosomes, which are found in the nucleus and contain the hereditary material. In humans, there are 46 or 23 pairs of chromosomes, out of which 22 pairs are autosomes, and a pair is the sex chromosomes or allosomes.
Autosomes are known to transfer the somatic characters to the next generation of the same species, while sex chromosomes decide the sex or gender of the upcoming generation.
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