Question

7. Explain the difference between gene duplication and divergence, and the role of each. Give one example of a protein that demonstrates this process.

Answer 1

Gene duplication

Gene duplication, followed by gene divergence. It is a source of new genes in genomes. Gene divergence- divergence means to go in different directions. The sequence of the gene copies is different from each other because of the accumulation of mutations.
Genes can get duplicated (exact copies) when there is unequal crossing over of chromosomes. For example, during the process of meiosis, homologous chromosomes often exchange equivalent regions. Crossing over that will result in the exact exchange of equivalent regions between the two chromosomes. Gene duplication may occur multiple times, which leads to multiple copies of the same gene on a single chromosome.
Gene divergence:
If there is more than one copy of a gene on a single chromosome, there is a possibility of the copies that become different gradually and these gene copies undergo mutations. Mutations in these copies don't harm to the organism if there is at least one old (original) copy. Because of this gene divergence, the mutant copies can be passed on to the offspring in which one original copy of the gene, a and one variant, b, will give rise to two different proteins. The acquisition of differences caused by a mutation in the genes is called "divergence".
The process above is how the original single globin gene is thought to have given rise to two genes that became the α and β globin genes. Subsequent duplication and divergence in these two genes gave rise to the variant forms of α, and β is seen in humans.

Example: The globin gene family, specifically the hemoglobin. The hemoglobin protein consists of red blood cells. It comprises two varieties of the hemoglobin protein alpha and beta hemoglobin each produced by a hemoglobin gene. Two alpha and two beta hemoglobin proteins to form a tetrahedral complementary shape that forms the interior of the tetramer with the Fe (iron) containing oxygen (O2)-binding regions that occupy the ends of the tetrahedron. Thus, the two forms of hemoglobin that arose from gene duplication and the ancestral hemoglobin arises from duplication of an ancestral gene for both myoglobin and hemoglobin.