What are mutations?
A mutation is a change in the DNA base sequence. The base sequence is the order in which our codons, made of nitrogenous bases, line up along our DNA. These mutations happen all the time within our cells spontaneously, especially when DNA is being replicated. Mutations can be passed on to offspring as well.
Although these mutations occur naturally, certain factors may increase the likelihood of their occurrence. Two examples of these factors are Carcinogens, which are harmful chemicals found in things like cigarette smoke, and certain types of radiation, such as Gamma Rays and X-rays.
There are two types of mutations. Genetic mutations occur when there is a change to one gene and its DNA, and Chromosomal mutations, which occur when there is a change in the entire chromosome itself. Genetic mutations are referred to as point mutations, which means that there is a change in one or a few nucleotides, since it is at one point. Chromosomal mutations may change the number and/or location of genes on the chromosome.
How do mutations work in the body?
(Arizona.edu)
If the diagram above had a letter substituting one of the letters in the sequence (such as an A for a T), the sequence of amino acids would change, causing a different shape or function than was intended. For example, if this DNA encodes an enzyme, a mutation could alter the shape of the active site.
Most of the time, mutations don’t have much of a significant effect, though this doesn’t mean it’s always like that. They can also be beneficial in certain cases. Mutations also usually occur in non-coding DNA, which plays an important role in the expression of genes and how they function.
Type of mutations in DNA/genes.
- Substitution - One nitrogenous base is replaced by another
- Insertion - An extra base is inserted into the sequence
- Deletion - A base is deleted from the sequence
Insertion and Deletion are far more harmful than Substitution, forcing everything to be pushed over in a certain direction.
Type of mutations in Chromosomes.
- Deletions - loss of part or all of the chromosome
- Duplication - Extra parts of chromosomes (duplicates)
- Inversions - Reverse direction of how the chromosome is read
- Translocation - One part of the chromosome breaks off and attaches itself somewhere else.
Thank you to Geetha S. for editing this article!