Genetic Change: The Biological Significance of Mutations

The term "mutation" is widely known in society due to its frequent mention in both science fiction movies and during the pandemic. Generally, the word "mutation" carries a negative connotation in our minds. But is that truly the case? In this article, we will explore the meaning and significance of mutation from a biological perspective and provide a brief overview.

What is Mutation?

Let’s start with the most basic definition: A mutation refers to changes that occur in the genetic code of living organisms. DNA, or genetic code, contains information about the structural characteristics of an organism. Traits such as our height, eye color, hair color, and susceptibility to diseases are determined by the information contained in DNA. For an organism to survive, it is essential that the genetic information passed down from previous generations is mostly accurate. This way, sudden changes between generations can be avoided, maintaining genetic balance. Over time, some control mechanisms have developed to ensure the accurate transfer of genetic material. These mechanisms aim to minimize errors that may occur during the replication of genetic information. For example, during the DNA matching process, enzymes that perform high-accuracy checks help ensure correct copying.

Although these mechanisms work with high efficiency, they do not operate with 100% accuracy, and sometimes errors occur in the organism's genetic sequence. These changes in DNA can subsequently affect the RNA and protein structure, leading to changes in the organism.

How Do Mutations Occur?

Another topic to address when discussing mutations is how they occur. Mutations can be inherited from an organism's ancestors (parents) or can arise spontaneously. Spontaneous mutations in an organism can result from internal factors, such as DNA copying errors, or external factors, like toxic chemicals, tobacco, asbestos, and sunlight. These factors can lead to changes in molecular mechanisms, resulting in some differences within the organism.

Are Mutations Always Harmful?

One of the first questions that comes to mind when discussing mutations is whether these changes are always harmful. There is a widespread perception that mutations generally have a negative impact on the individual. However, most mutations that occur in living organisms are neutral, meaning they provide neither an advantage nor a disadvantage. Some mutations can be harmful or beneficial. Yes, you heard that right; there are mutations that can positively impact an organism's life. Therefore, it is not biologically accurate to associate mutations solely with negative diseases. The essential point here is that, as mentioned, most mutations have neither a negative nor a positive impact on the organism.

So, if most changes in DNA do not lead to positive or negative changes in organisms, one might wonder why such a mechanism exists in the living world. The fundamental reason for this is to ensure diversity among organisms. As we mentioned, for an organism to survive, it needs to receive genetic information from previous generations with minimal changes. However, if this information were passed down without any changes, it would be clear that diversity among organisms could not be maintained. Such a situation would negatively affect the ability of organisms to adapt to changing conditions, ultimately impacting the continuation of generations. Therefore, mutations are one of the critical mechanisms for ensuring diversity among individuals and the persistence of life. In summary, while accurately transferring DNA is essential for genetic balance, the fact that control mechanisms do not work with 100% efficiency allows for minor errors or changes, which is vital for the diversity of life.

For example, in E. coli bacteria, the DNA copying error rate is approximately 1 in  10⁻¹⁰. This means that only one uncorrected copying error occurs in every 1,000 replication processes of the E. coli genome.

Sometimes, whether a mutation is advantageous or disadvantageous may vary depending on the organism in which it occurs. For example, frequent antibiotic use can lead to antibiotic resistance in the relevant bacteria. The bacteria undergo changes to protect themselves against the antibiotic, becoming resistant. This is a beneficial mutation for the bacteria because it increases their chances of survival. However, it poses a significant problem for humans, as it becomes more challenging to combat diseases caused by these bacteria.

Sickle cell anemia is another good example for explaining the topic. In individuals with this condition, a mutation leads to the production of abnormal hemoglobin, causing red blood cells to take on a sickle shape. This can hinder the efficient transport of oxygen in the person’s blood. However, it has been observed that individuals with this mutation have a lower risk of contracting malaria. Malaria settles in red blood cells and multiplies there; however, it cannot multiply in red blood cells of individuals with sickle cell anemia. While this situation is certainly negative for the person suffering from sickle cell anemia, it is advantageous in terms of malaria resistance. Thus, when evaluating mutations as beneficial or detrimental, a one-sided perspective is not sufficient.

Finally, we can cite the lactose digestion mechanism as an example of mutations occurring in humans. Normally, the amount of the enzyme that digests lactose (the sugar found in dairy products) decreases during adulthood. Therefore, lactose intolerance may occur in adulthood. However, in populations where dairy consumption is common, individuals have adapted to continue digesting milk sugar into adulthood.

Can We Gain Superpowers in an Instant?

Since childhood, many of us have enjoyed watching science fiction movies, where our hero typically gains superpowers after being exposed to a sudden stimulus that causes mutations in their body. For example, Spider-Man acquires spider-like abilities from a spider bite, and The Flash gains super speed from being struck by lightning. But is such a thing scientifically possible? Mutations accumulate gradually over long periods. This way, sudden changes can be avoided to maintain balance. Therefore, from a scientific perspective, it is not expected that a single mutation could lead to such significant changes in individuals in a short time. In other words, such a scenario does not align with real science.

In conclusion, mutations are fundamental building blocks of biological diversity and play a crucial role in the evolutionary processes of living organisms. While most mutations are neutral, some can lead to diseases or advantageous traits. By broadening our scientific perspective, we should remember that mutations are not only negative changes but also important mechanisms that ensure the diversity of life.

Referances

1) Terence A Brown. (2002). Chapter 14, Mutation, Repair and Recombination. Genomes. 2nd Edition, 1–36.

2) Ripley, L. S. (2013). Mutation. Brenner’s Encyclopedia of Genetics: Second Edition, 3, 534–539. https://doi.org/10.1016/B978-0-12-374984-0.01007-X

3) Popovic, A., & Orrick, J. A. (2024). Biochemistry , Mutation. 1–13.

4) Bhagavan, N. V., & Ha, C.-E. (2015). DNA Replication, Repair, and Mutagenesis. Essentials of Medical Biochemistry, 401–417. https://doi.org/10.1016/b978-0-12-416687-5.00022-1

5) https://www.khanacademy.org.tr/fen-bilimleri/biyoloji/molekuler-biyoloji/mutasyonlar/genetik-mutasyona-giris/9477 Accessed: 2024-10-03