Autosome: Definition, Function, Examples, Chromosomes and Biological Terms

Also called somatic chromosome, it is any chromosome that is not sexual.

Unlike prokaryotic cells, eukaryotic cells have many chromosomes in which they pack their DNA. This allows eukaryotes to store much more genetic information.

Most eukaryotic organisms reproduce through sexual reproduction, which means that each individual has two copies of each chromosome. One copy is inherited from one parent, while the other is inherited from the other parent.

This system improves genetic diversity and protects against some diseases, since it allows individuals to inherit genes from the immune system of two different parents, and having two copies of a gene often allows a healthy copy inherited from one parent to “cover” “A copy of a gene that has been corrupted through a harmful mutation.

It is normal for diploid eukaryotic organisms (those that have a complete set of inherited chromosomes through sexual reproduction) to have two copies of each autosome.

Sex chromosomes are considered separately from autosomes, since their inheritance pattern works differently. In humans, the sex chromosomes are known as the X chromosome and the Y chromosome. Other animals, like birds, use a different system of sex chromosomes.

During the process of meiosis that creates eukaryotic sex cells, the sex cells “remix” the DNA between their two copies of each autosome in the crossing process. The result is a unique set of chromosomes that have a mixture of material from both parents of the individual.

Then, the sex cell discards one of the resulting remixed autosomes, which results in a gamete cell that has only one copy of each autosome.

When two gametes combine, they produce a cell that will become a new individual that will own a copy of each chromosome of each parent. The individual’s unique genetic profile will include DNA from each of his four grandparents.

During the growth of a multicellular organism, it is normal for a cell to make a complete copy of each of its chromosomes and deliver a copy to each daughter cell.

When errors occur in the distribution of chromosomes during meiosis or early embryonic development, serious diseases can occur because many cells in an individual’s body have an incorrect amount of chromosomes.

Because each chromosome contains thousands of genes, having too many or too few chromosomes can cause serious imbalances in gene expression. In humans, many pregnancies that do not survive in the first trimester are cases in which the embryo inherited an incorrect amount of chromosomes and could not survive.

Other errors in chromosomal duplication can cause milder syndromes, such as Down syndrome , which is caused by inheriting an extra copy of chromosome 21 from one of the parents.

Autosome function

Each autosome stores many thousands of genes, each of which performs a unique function in the body’s cells.

Under normal circumstances, each chromosome follows a “map” that is shared among individuals of the species.

This allows the cells to “know” where to start gene expression when they want to express a particular gene. It is believed that the factors that affect gene expression use this “map” to respond precisely to the needs of a cell.

When the autosomes are healthy, this allows the cells to perform an amazing variety of functions. Each of the hundreds of subtly different cell types in a eukaryotic organism expresses a different combination of genes in the right place at the right time.

What allows the enormous variety of cellular functions that we see in eukaryotic organisms like us.

Each of our cells contains the necessary complement of genes to reproduce our entire body. The differences between brain cells, skin cells and muscle cells are made by cells that transcribe the right genes in the right places at the right times.

Our bodies do it well almost all the time! But biologists often learn how something works by looking at the cases in which it breaks, and seeing what happens when the mechanism does not work properly.

In the case of autosomes and their carefully arranged “map” that allows the complexity of our bodies, problems can arise when the chromosomes are broken and their pieces end up in the wrong place.

This event, called “translocation”, can cause genes to express the wrong genes at the wrong time. Some cancers can be caused by translocations that lead to errors in cell development and reproduction.

Examples of autosomal disorders

Trisomy 21 (Down Syndrome):

Down syndrome occurs when a person inherits all or part of an additional copy of chromosome 21 from one of the parents. This usually occurs due to a one-time error in meiosis and is not transmitted from generation to generation.

People with Down syndrome have a variety of unusual features and symptoms related to skeletal tissue (unusual skeletal form, weak ligaments), nervous tissue, cognitive disabilities, poor muscle tone and are at higher risk of some diseases due to extra expression of material on chromosome 21.

Due to the variety of symptoms seen in Down syndrome, some people with Down syndrome can complete regular education and have independent careers, while others may need special education classes and may not be able to function independently in the place of job.

The only known risk factor for Down syndrome is having older parents, which can increase the chances that parents’ bodies incorrectly classify chromosomes during meiosis.

Scream of the Cat :

Cri du chat, also known as “5p chromosome deletion syndrome” or ” Lejeune syndrome “, occurs when a person inherits only one copy of part of chromosome 5. Some people with cri du chat also have additional copies of other parts of the chromosome. chromosome 5

As with Down syndrome, cri du chat usually occurs due to an error in the classification of the chromosomes of the parents during meiosis.

The name of the syndrome comes from the French like “cry of the cat”, in reference to the unusual feline crying babies have with cri du chat due to their unusual skeletal and neurological characteristics.

Like people with Down syndrome, people with cri du chat can have unusual skeletons, weak muscles, and cognitive decline due to sub expression of the 5p chromosome section.

People with cri du chat can also have hearing loss, heart problems and microcephaly (a small head).

Philadelphia Chromosome

The Philadelphia chromosome is a chromosome found in many cancer cells in leukemia, which can give a clue to how cancer starts.

On the Philadelphia chromosome, chromosome 9 and chromosome 22 exchanged genetic material. The specific place where the two join creates a fusion protein, that is, a protein encoded by a fusion of two different genes, one from chromosome 9 and one from chromosome 22.

This gene converts cellular replication into “always activated” and, as a result, leads to the uncontrolled replication of cells that never mature and become functionally adequate. Leukemia occurs when these non-functioning cells multiply out of control and destroy healthy and functional tissue.

Some scientists believe that chromosomal translocations are a common cause of cancer. At least fifteen different types of cancer have been found that often involve chromosomal translocation, often resulting in the creation of fusion proteins.

Related biology terms

Gametes: the sex cells used by species that reproduce sexually to produce offspring with new combinations of genes, created by remixing and combining genetic material from each parent.

Genetic balance: the theory that genes must be expressed in the correct amount within cells. In the theory of gene equilibrium, too much or too little expression of a given gene compared to others produces cellular problems.

Gene expression: the process by which genes are converted into proteins, which perform important functions in a cell.