What are the different types of genetic mutations?  

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jking22 eNotes educator| Certified Educator

Many different types of genetic mutations exist, with each having various effects on the proteins they code for within the body. One such type is a missense mutation. In a missense mutation, the problem arises due to the change of one DNA base pair for another, leading to the presence of a different amino acid than originally intended in the final protein. Another type of mutation is a nonsense mutation. A nonsense mutation is similar to a missense mutation in that it again occurs when one DNA base pair is changed from its original to another. It is different, however, because in this mutation the change does not lead to a different amino acid being present, but rather signals for a stop codon, causing the protein to prematurely stop being made. This can lead to shortened proteins that are compromised in function or that may not function at all. A third type of mutation is an insertion. As the name implies, this type of mutation occurs when a new DNA base pair, or pairs, are added into a gene. Conversely, another type of mutation is a deletion, which, as the name implies, occurs when a DNA base pair, or pairs, are deleted from a gene. In a duplication mutation, a part of the DNA is copied one or more times into the gene, resulting in a change in the overall DNA sequence compared to normal.

Frame shift mutations are also a form of genetic mutation. These mutations occur when DNA base pairs are either lost or gained, causing a change in the “reading frame” of DNA. This reading frame is made up of three base pairs that code for a specific amino acid; therefore, an insertion, deletion, or duplication mutation can also lead to a frame shift mutation. Finally, a repeat expansion can occur, leading to genetic mutation. In the case of repeat expansion, a short sequence of DNA is replicated in its entirety in the gene, and can appear a number of times.

Overall, all of these mutations can affect which amino acid(s) coded for by the DNA present. This change can alter the final conformation of the protein and can lead to improper function.

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