The Genes we lost along the way

 Mutations are happening all the time in the DNA of any species, due to which diversity is created in the species - Genes contain instructions for making proteins - If a gene is mutated, i.e. its letters change. The gene stops working the mutated gene is no longer able to make the protein, so the protein stops doing what it does in the body.

The Genes we lost along the way

Pseudo genes:

Our DNA contains about 20,000 genes that are used to make proteins. But our genome contains more or less dysfunctional genes that were used to make proteins in the bodies of our ancient ancestors, but due to mutations in the process of evolution, have now become dysfunctional and do not make any proteins. Such genes are called pseudogenes - now we have also known the location of these pseudogenes in our DNA.

Most pseudogenes occur when two or more copies of a gene are made during DNA replication—in which case all copies continue to make the correct protein—if one of the genes becomes inoperative. The remaining copies of this gene continue to function - but there are some pseudogenes that have only one copy in our DNA, but that copy has become dysfunctional.

The gene for making vitamin C:

One such dysfunctional gene is the Galop gene that makes vitamin C—this gene makes an enzyme that is used in reactions to make vitamin C—about 600 million years ago, a mutation occurred in this gene in our ancestors that caused People with this mutated gene stopped making vitamin C. Normally, when a gene stops working, the fitness of individuals with that mutation is reduced—in the process of natural selection, such individuals are usually unable to produce offspring and thus become extinct. Such a deleterious mutation is also eliminated from the population - but if the mutation increases the fitness of individuals, the mutation increases in the population with each generation, and in thousands of generations only individuals with the same mutation survive. It remains, meaning that now every individual of this species will have this mutation.

Interestingly, although this mutation in the Gulop gene caused loss of vitamin C production in our ancestors, this mutation did not reduce the fitness of our ancestors because at that time our ancestors lived mostly on fruits, which included Vitamin C is abundant - this was a time when forests in Africa and other areas near the equator (called tropical areas) were growing rapidly, so there was an abundance of fruit trees - so our ancestors They were getting vitamin C through the diet and were not harmed by the body's inability to make vitamin C - the Gulop gene is often present in the correct state in mammals, but in the DNA of chimpanzees, gorillas and humans it is absent. The gene is in an inactive state.

Uric Acid Breakdown Gene:

There are many other similar dysfunctional genes in our DNA that document our evolutionary history—for example, the UoX gene was present in our ancestors 450 million years ago—a gene that processes uric acid from bacteria. Functioning in many animals, from mammals - this gene makes the enzyme uricase that breaks down uric acid - uric acid is produced as a waste product from the metabolism of all animals - but 17 million years ago A mutation in our ancestors caused this gene to stop working - but this dysfunctional gene is still present in a non-functional state in all apes (including humans) and its fossils can be seen on our chromosome 1 - this A mutation in a gene causes apes and humans to have 3 to 10 times more uric acid in their blood than other animals, which causes joint pain - uric acid crystals begin to accumulate between our joints, causing joint pain. I get inflammation - this disease is called gout -

The question is, how did such a useful gene become inactive? In 2014, a team of scientists compared the metabolism of the Uricase enzyme in many mammals. Created Structures - Because different mammals have different mutations in this gene, we can predict differences in enzymes and protein structures in their ancestors - this prediction leads scientists to make the exact same protein in the lab. were able to make what was made in the body of our ancestors 90 million years ago in which this gene had not yet been disabled - this synthetic protein was introduced into the body of the current animals, and this protein began to make the enzyme that breaks down the uric acid. process the By the same process, when the protein that was formed in the body of our ancestors 40 million years ago was formed, this protein was somewhat weakened and its efficiency in breaking down uric acid was reduced - 200 million years ago. The efficiency of this protein was further reduced due to mutations in the gene - 170 years ago, the last mutation occurred in this gene, which completely disabled the gene.

Bad Jeans and Fitness:

The question is, if the inactivation of this gene was increasing the amount of uric acid in the body of our ancestors, which is harmful to the body, then why is this mutation still present in our genes? Seventy million years ago today, Earth's surface temperature was dropping and Earth was entering an Ice Age - Our ancestors lived on fruits at that time - fruits were not available all year round because of the cold, trees bore fruit only in summer - a side effect of excess uric acid is that in its presence fructose (which (a type of sugar found abundantly in fruits) causes the body to make more fat after eating it - so the inactivation of this gene enabled our ancestors to make more body fat to store them through the winter. And the body used to break down this fat for energy—as if disabling this gene increased the overall fitness of our ancestors and increased their chances of survival.

The science of genomics is advancing very rapidly and we are becoming able to study DNA to understand not only how the DNA of any species controls the structure of its body, but One can also read the entire evolutionary history of this species from fossil genes in DNA.

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