Mutations are changes in genetic code that generally occur to give a species an evolutionary advantage. This adjustment in the sequence of genes can be divided into several types such as beneficial, harmful, and neutral.
Within these groups, there are also several examples. Today, we will be taking a closer look at examples of beneficial mutations and their impacts on life.
A mutation is not a temporary alteration. It is a permanent change in the nucleotide sequence of DNA.
Such a mutation means that the amino acid sequence of proteins that are encoded by DNA or genes are altered. Therefore, the whole makeup, as well as function, of a body’s cells and tissues may be modified.
Mutations in organisms can occur because of numerous reasons. Some causes could be cell division (mitosis & meiosis), viruses, radiation, and/or exposure to carcinogens (mutagens).
When a mutation occurs in higher organisms, it is either germ-line or somatic. Somatic simply refers to the mutation of body cells.
This type of mutation is not usually passed on to any offspring. Germ-line mutation happens in germ cells and, unlike somatic mutations, it is passed onto offspring through reproduction cells.
When considering the long-term effects of a mutation in a population, it can be classified as either beneficial, deleterious, and neutral (more favorable, less favorable, neutral).
Today, we will be discussing beneficial mutations in detail and exploring some examples.
What Is A Mutation?
Mutations have happened throughout history. You are the product of countless mutations over countless generations.
Ask yourself, ‘can I digest dairy products like cheese or milk?’ and ‘do I have green eyes?’ If you can digest dairy products and you have green eyes, then this is because of a mutation in your DNA.
Mutations are essentially alterations in your genetic code. DNA (Deoxyribonucleic Acid) is the genetic material that is used to code and is responsible for a range of physical characteristics.
DNA is constructed from four separate molecules known as ‘bases.’ These are represented by the four letters A, T, C, and G. However, the entire genetic code of a single human holds billions of bases. It is when these bases change that we experience a mutation.
Some mutations can cause negative or detrimental effects. Examples of these are Klinefelter or Down Syndrome. Many other mutations are benign and go unnoticed.
This is because they occur in regions of DNA that are not used actively. An example of this would be blue eyes. This color of eyes came about from an alteration in the protein that is responsible for the pigmentation in eyes. But, this is just one basic example of a mutation.
On occasions, mutations can arise which give individuals or populations an advantage. These are known as beneficial mutations. Let’s explore some examples below.
Examples Of Beneficial Mutations
A beneficial mutation is retained in a population. Such a mutation forms adaptations as it evolves. As for deleterious mutations (less favorable), these are not retained in a population and can be removed through natural selection.
The third category, a neutral mutation, has no large impact on a population. Instead, neutral mutations expand via a genetic drift.
The environment of a population tends to determine the impact and effects a mutation has. Below are some interesting examples of beneficial mutations that improve the wellness of particular organisms.
Murray Gray is a breed of beef cattle. However, this unique breed was obtained from another traditional species of cow.
The calves of this breed were produced by cows that were more productive than other breeds. This led farmers to soon realize that there was a difference.
Therefore, they began breeding from these unique offspring. Eventually, the Murray Breed was produced with very favorable characteristics that became popular throughout Australia. Over time, Murray Grays spread into other countries and their population exploded.
Antibiotic Resistance – Bacteria
Antibiotics have been used for over a century to treat various diseases that are caused by different forms of bacteria. However, the continuous and constant use of antibiotics in different populations has led to a resistance being developed amongst the targeted bacteria.
More often than not, when exposed to a non-antibiotic environment, this antibiotic resistance reduces the fitness and wellness of a bacterial population.
Also, the resistant bacteria cannot typically reproduce as quickly as bacteria without any mutation. Therefore, the progression of a disease is slowed down.
Nylonase bacteria is capable of eating short molecules of nylon, also known as nylon-6. Nylonase is simply another example of a beneficial mutation, but in bacteria.
The mutation in bacteria happens when a single nucleotide inserts itself into some genetic material.
Researchers believe that this mutation may have occurred when nylon was invented during the late 1930s and through the 1940s. Today, nylonase is used in wastewater treatment plants.
Gene Mutation In Almond Trees
Amygdalin is a bier chemical that transforms into cyanide when inside the body. This chemical is found inside almond seeds, and researchers have discovered that consuming wild almonds can be fatal.
However, a single gene mutation occurred in wild almond trees. This resulted in a variety of almond trees that did not synthesize amygdalin anymore. When this was discovered, the non-bitter species was cultivated and continues to be grown to this very day.
CCR5 (Cysteine-cysteine chemokine receptor 5) is a receptor molecule found in white blood cell membranes and in nerve cells.
Within a cell, CCR5 allows chemokines to enter. These then signal an inflammatory response to any kind of foreign particles found inside.
A gene that is responsible for coding Cysteine-cysteine chemokine receptor 5 is located in the human chromosome 3. Here, a mutation occurred known as CCR5-delta32. This saw 32 pairs get deleted, thus affecting the normal function of the CCR5 receptor molecule.
In the early stages of HIV, the deadly virus usually enters the body through CCR5. But, the mutation of CCR5 helps to stop HIV from entering.
Therefore, those who carry homozygous mutated CCR5-delta32 are completely resistant to the HIV infection. Heterozygous receptor molecules slow down the progression of the disease. The result? CCR5-delta32 provides total or partial immunity to HIV.
It’s not all positive news with the CCR5-delta32 mutation, however. One drawback is that it is associated with a chronic liver disease known as primary sclerosing cholangitis (PSC).
This is a long-term progressive liver disorder and it can also affect the gallbladder. It is characterized by the inflammation and fibrosis of the intrahepatic and extrahepatic bile ducts. This results in bile draining away from the gallbladder.
When we look throughout nature, some of the most productive animals and plants have evolved through mutations.
The effects of these mutations have been beneficial for a certain species and have often occurred due to natural selection. Therefore, harmful changes are prevented over a prolonged period of time and favorable alterations continue in a population.
Mutations are not something that happen overnight. They can occur over thousands, even millions of years. But, on rare occasions, they can arise in a very short amount of time and have a considerable positive impact on populations.
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