Gene Duplication: What is it?

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Gene duplication is the process by which a chromosome or piece of DNA is duplicated, resulting in an additional copy of a gene. Gene duplication is also referred to as chromosome duplication or gene amplification. Duplication, which means doubling, results in two identical genes. One or both of these genes can change over time through mutations to create two new, different genes.

Deoxyribonucleic acid (DNA) is unique to every organism and is the same in every cell that composes it. Genes are sections of DNA that determine inheritance and are housed in sections of the body known as chromosomes. This constitutes the genetic makeup of all organisms.

Gene duplication usually occurs due to an error during meiosis. Meiosis occurs only in those cells that produce sex cells, such as sperm and ova in humans. During meiosis, mother cells with two copies of chromosomes produce four daughter cells that each have only one copy of each chromosome. This is so that when reproduction occurs, the cell that is created by the fusion of the sperm and egg will have the right amount of DNA.

During meiosis, gene duplication is likely to occur as chromosomes cross over and recombination occurs. The strands of chromosomes can break and rejoin the opposite chromosome, so that genetic information is moved from one chromosome to another. If the recombination is unequal or occurs with different amounts of DNA, duplication can occur.

Another way duplication can occur is if the entire chromosome is replicated twice. This mistake will cause one of the daughter cells to have an extra copy of the chromosome and all the extra genetic material. If this cell fuses with another cell during reproduction, it may or may not result in a viable zygote.

The last way gene duplication can occur is through retrotransposition. During reverse transposition, DNA sequences are copied into RNA and then back into DNA instead of being translated into proteins. This results in extra copies of that DNA present within the cell, which can rejoin the chromosomes already there. Any genes found along these DNA sequences will have been duplicated in the process.
When gene duplication occurs, a copy of the original is created, called a paralog gene. It is possible for both or one of the genes to mutate, however this is not always the case. During the process of mutation or change, genes can acquire different functions from the original gene.

The original gene can also mutate, forming two genes that are different from the original gene before duplication. Gene duplication is considered to be a driving force in the emergence of new genes and thus changes in normal biological processes. The processes of mutation and gene duplication both play key roles in evolution.

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