![]() A deletion mutation occurs when a nucleotide is skipped or absent from the replicated strand. ![]() An insertion occurs when an extra nucleotide is incorporated into the DNA sequence during replication. Insertions and deletions are two other types of point mutations. Read more about Gene Mutations Insertions and deletions If the affected amino acid is at a critical residue such as in an enzyme’s active site, or at an important binding site, the function of the entire protein could be abolished. An easy way to remember this is ‘S’ for ‘synonymous’ and ‘ silent’, the mutation is unlikely to have an effect and therefore is silent. Alternatively, the nucleotide substitution could not affect the encoded amino acid (since multiple codons can occur for the same amino acid). This is called a non-synonymous mutation. The substitution could change the amino acid that the DNA encodes, changing the protein sequence. However, this does not mean the resulting effects will be small. This type of mutation only affects one codon. Substitution refers to the case in which one nucleotide is incorrectly swapped during DNA replication for another nucleotide, meaning the correct nucleotide is replaced with an alternative nucleotide. Point mutations occur through insertion, substitution or deletion. This depends on the location of the mutation. These usually take place during DNA replication, and their consequences can be benign or can be devastating. Point mutations refer to changes to a single nucleotide. This is important for the consequences of mutations. Several different codons can code for the same amino acid. This translation relies on the triplet code, whereby a sequence of three nucleotides codes for a particular amino acid. To understand how mutations can have such varied effects, we need to remember how DNA sequences work The role of DNA sequences –a reminderĭNA sequences are transcribed into an mRNA sequence, which is then translated into a protein. The changes to the DNA can occur in a variety of ways, affecting sequences and proteins to different extents. Chromosomal mutations include large-scale deletions, inversions, duplications and translocations.ĭNA sequences can be changed through mutations.Insertions and deletion of single nucleotides can cause frameshift mutations, changing the sequence of the entire protein.The resulting mutations can be missense (amino acid change in sequence) or nonsense (premature stop codon is encoded. Substitution of nucleotides can be synonymous (silent) or non-synonymous (change amino acid).Mutations can occur on a single nucleotide scale (at the level of point mutations), or on a much larger scale (where segments of whole chromosomes are affected.Mutations occur through various mechanisms that can impact genes, chromosomes, and outcomes differently. ![]()
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