Autosomes are any chromosome that is not a sex chromosome. The members of an autosome pair in a diploid cell have the same morphology, unlike those in allosome pairs which may have different structures. The DNA in autosomes is collectively known as atDNA or auDNA. Ex: Humans have a diploid genome that usually contains 22 pairs of autosomes and one allosome pair. The autosome pairs are labeled with numbers (1–22 in humans) roughly in order of their sizes in base pairs, while allosomes are labeled with their letters. By contrast, the allosome pair consists of two X chromosomes in females or one X and one Y chromosome in males. Unusual combinations of XYY, XXY, XXX, XXXX, XXXXX, or XXYY, among other allosome combinations, are known to occur and usually cause developmental abnormalities.
They still contain sexual determination genes even though they are not sex chromosomes. For example, the SRY gene on the Y chromosome encodes the transcription factor TDF and is vital for male sex determination during development. TDF functions by activating the SOX9 gene on chromosome 17, so mutations of the SOX9 gene can cause humans with an ordinary Y chromosome to develop as females.
Differences Between Autosomes and Sex Chromosomes
|Such a pair of chromosomes that regulate the somatic characters of the body are known as autosomes.||The pair of chromosomes determines the sex of an organism, as they regulate the sex-linked traits.|
|They are named or numbered from 1 to 22.||These are recognized by the letters XO, XY, ZW, and ZO.|
|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 is 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 the X chromosome has more than 300 genes.|