Since the nucleotide sequences are read in groupings of three, this will cause a shift in the reading frame. Insertions and deletions can cause frame-shift mutations when base pairs that are not a multiple of three are added to or deleted from the sequence. This type of gene mutation is dangerous because it alters the template from which amino acids are read. Mutations can also occur in which nucleotide base pairs are inserted into or deleted from the original gene sequence. If this process is ended too soon, the amino acid sequence is cut short and the resulting protein is most always nonfunctional. A stop codon signals the end of the translation process and stops protein production. Nonsense Mutation: This type of mutation alters the nucleotide sequence so that a stop codon is coded for in place of amino acid.Using our previous example, if the codon for arginine CGC is changed to GGC, the amino acid glycine will be produced instead of arginine. The change may not have much effect on the protein, may be beneficial to protein function, or may be dangerous. This change alters the resulting protein. Missense Mutation: This type of mutation alters the nucleotide sequence so that different amino acid is produced.If the DNA sequence CGC is changed to CGA, the amino acid arginine will still be produced. For example, the amino acid arginine is coded for by several DNA codons including CGT, CGC, CGA, and CGG (A = adenine, T = thymine, G = guanine, and C = cytosine). Amino acids are coded for by three-nucleotide sets called codons. This is because multiple genetic codons can encode for the same amino acid.
0 Comments
Leave a Reply. |
AuthorWrite something about yourself. No need to be fancy, just an overview. ArchivesCategories |