Life Sciences: Point Mutation
Understanding DNA is a complex task some people have dedicated their entire professional lives to understand. It is virtually impossible to break DNA down to the point where a layman is able to fully grasp the concepts of how DNA works. There is also a need to understand where things could go wrong. As DNA splits to create new cells, there typically are no problems. The off chance that there is a problem, scientists look for where an error in the formation of the DNA occurred.
One area of error is known as point mutation. “Point mutation is a change within a gene in which one base pair in the DNA sequence is altered. Point mutations are frequently the result of mistakes made during DNA replication, although modification of DNA, such as through exposure to X-rays or to ultraviolet radiation, also can induce point mutations” (Sinah, 2014).
Figure 1: Original Sequence versus Point Mutation
There are different ways to dive deeper into point mutation. First would be categories of the mutations and secondly, the types of mutations. The two categories of point mutation are hereditary and acquired. “Heredity mutations are inherited from a parent and are present throughout a person’s life in virtually every cell in the body. Acquired mutations occur at some time during a person’s life and are present only in certain cells, not in every cell in the body. These changes can be caused by environmental factors such as ultraviolet radiation from the sun or can occur if an error is made as DNA copies itself during cell division. Acquired mutations cannot be passed to the next generation” (What is a Gene Mutation, 2018).
There are three types of point mutation that are possible; missense mutations, nonsense mutations, and frameshift mutations. An article written by Jennifer Stearns and Michael Surette states:
- “Missense mutation, this is when the wrong nucleotide is added within the coding region of a protein gene and this changes the amino acid that is incorporated into the resulting protein.
- Nonsense mutations, the result of the wrong nucleotide being added within the coding region of a protein gene, creating a stop codon. The resulting protein will be shorter then it supposed to be, or truncated.
- Frameshift mutations – caused by the loss or addition of a nucleotide that changes how the pattern of three nucleotides per codon is read. The result is that, from this point forward, completely different amino acids may be incorporated into the protein.” (Stearns, 2014)
The easiest explanation of the search for chromosomal and gene mutations is from one of Saskatoon’s genetic doctors, Dr. Kelly Davis. She explains that best way to think about looking for mutated genes or a point mutation is like looking for a book in the library that you are not even sure if it exists. When you walk through the door of the library (your DNA) you start looking around to see if you what you are looking for pops out (chromosome abnormalities). You notice an area that you think would be worth looking at, so you go to that section (a specific chromosome). You examine the section and then narrow down to the shelf (gene), then the book (point mutation). When you open the book, you take a quick look through the book (deeper into the mutation) and you find the chapter, then paragraph and so on to the single letter. If no abnormalities were found on the chromosomes right off the start, there is no need to continue down that rabbit hole (Davis, 2017).
Davis, Dr. Kelly, interviewed by Jayna Schenn, Oct 10, 2017
Sinha, Surabhi. (2014 February 04) Point Mutation, Retrieved from https://www.britannica.com/science/point-mutation
Stearns, Jennifer, Michael Surette. (2014) Slight adjustment to the Genetic Code. Retrieved from
The national Science Foundation, Understanding Evolution. https://evolution.berkeley.edu/evolibrary/article/mutations_01 5 June 2018
US National Library of Medicine. (12 June 2018) What is a gene mutation and how do mutations occur? Retrieved from https://ghr.nlm.nih.gov/primer/mutationsanddisorders/genemutation
Your Genome. What types of mutations are there? https://www.yourgenome.org/facts/what-types-of-mutation-are-there