BSC 2010L Critical thinking 7

BSC 2010L Critical thinking 7 - effect ranges from no...

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Critical Thinking 7 There are certain differences between substitution mutation and insertion/deletion mutation. A substitution is the mutations that replace one nucleotide and its partner with another pair of nucleotides. An insertion/deletion is the mutations in which extra base pairs may be added or removed from the DNA of gene. Substitution mutation can be classified as silent mutation, missense mutation and nonsense mutation. A Silent mutation is when a mutation has no effect because it doesn't affect or change the phenotype of amino acid. For example, if a codon AAG changes to AAA, the phenotype isn't affected, because the codon would still code for same amino acid, lysine. A missense mutation is when the new nucleotide effects and changes the codon to produce an altered amino acid. One example is the sickle-cell disease. The 20th nucleotide of the gene is changed from the codon GAG to GUG, so the 6th amino acid is incorrectly substituted, which leads to the disease. The
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Unformatted text preview: effect ranges from no effect to huge effect. A nonsense mutation is when the new nucleotide changes a codon that specified an amino acid to one of the STOP codons (TAA, TAG, or TGA) which results in a shorter. The earlier this occurs in the gene, the more likely to be unable to function. In this respect, a nonsense mutation is most harmful in the substitution mutation. In general, insertions/deletions’ mutation is more harmful than substitution mutation. It is because an insertion/deletion mutation is when extra base pairs may be added or removed from the DNA of gene, which causes extensive missense and nonsense. It will affect the whole structure of the gene. If reading frame is altered, it's called frameshift mutation. Frameshift mutation occurs when the number of nucleotides inserted or deleted is not a multiple of three, so that every codon beyond the point of insertion or deletion is read incorrectly during translation....
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