Autosomes

Autosomes

Autosomes are any of the numbered chromosomes, as opposed to the sex chromosomes. Humans have 22 pairs of autosomes and one pair of sex chromosomes (XX or XY), making a total of 46 chromosomes in each cell. Autosomes are labeled with numbers from 1 to 22, generally in order of their size from largest to smallest.

Structure and Function

Autosomes are diploid in humans, meaning that each individual has two copies of each autosome, one inherited from each parent. These chromosomes carry the bulk of an individual's genetic material, including genes that determine a wide range of traits and functions.

Each autosome consists of a long strand of DNA that is tightly coiled and packaged with proteins called histones. This structure is known as chromatin. The DNA sequence on autosomes contains many genes, which are segments of DNA that code for proteins or functional RNA molecules.

Genetic Disorders

Many genetic disorders are linked to abnormalities in autosomes. These can be due to:

• Numerical abnormalities: Such as Down syndrome, which is caused by an extra copy of chromosome 21 (trisomy 21).
• Structural abnormalities: Such as Cri du chat syndrome, which is caused by a deletion of a portion of chromosome 5.

Inheritance Patterns

Autosomal genes can be inherited in several patterns:

• Autosomal dominant: Only one copy of a mutated gene is necessary for the manifestation of the trait or disorder. An example is Huntington's disease.
• Autosomal recessive: Two copies of a mutated gene are necessary for the trait or disorder to be expressed. An example is cystic fibrosis.

Comparison with Sex Chromosomes

Unlike autosomes, sex chromosomes (X and Y) determine the sex of an individual. Males have one X and one Y chromosome, while females have two X chromosomes. The genes on sex chromosomes are involved in sex determination and other sex-specific traits.

Research and Implications

Research on autosomes has significant implications for understanding human genetics and disease. Techniques such as genome-wide association studies (GWAS) often focus on autosomal regions to identify genetic variants associated with complex diseases.

See Also

• Chromosome
• Genetic disorder
• Mendelian inheritance

References

• Alberts, B., Johnson, A., Lewis, J., Raff, M., Roberts, K., & Walter, P. (2002). Molecular Biology of the Cell. 4th edition. New York: Garland Science.
• Strachan, T., & Read, A. P. (2010). Human Molecular Genetics. 4th edition. Garland Science.