Nonsense mutations – Video

Posted: February 10, 2013 at 7:45 am

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Video Link: https://www.youtube.com/watch?v=pLGOf6BDzf0



Nonsense mutations
For more information, log on to- shomusbiology.weebly.com Download the study materials here- shomusbiology.weebly.com In genetics, a nonsense mutation is a point mutation in a sequence of DNA that results in a premature stop codon, or a nonsense codon in the transcribed mRNA, and in a truncated, incomplete, and usually nonfunctional protein product. It differs from a missense mutation, which is a point mutation where a single nucleotide is changed to cause substitution of a different amino acid. Some genetic disorders, such as thalassemia and DMD, result from nonsense mutations. DNA: 5 #39; - ATG ACT CAC CGA GCG CGA AGC TGA - 3 #39; 3 #39; - TAC TGA GTG GCT CGC GCT TCG ACT - 5 #39; mRNA: 5 #39; - AUG ACU CAC CGA GCG CGA AGC UGA - 3 #39; Protein: Met Thr His Arg Ala Arg Ser Stop Suppose that a nonsense mutation was introduced at the fourth triplet in the DNA sequence (CGA) causing the cytosine to be replaced with thymine, yielding TGA in the DNA sequence. Since TGA is transcribed-then-translated as UGA, the resulting transcript and protein product would be: DNA: 5 #39; - ATG ACT CAC TGA GCG CGA AGC TGA - 3 #39; 3 #39; - TAC TGA GTG ACT CGC GCT TCG ACT - 5 #39; mRNA: 5 #39; - AUG ACU CAC UGA GCG CGU AGC UGA - 3 #39; Protein: Met Thr His Stop The remaining codons of the mRNA are not translated into amino proteins because the stop codon is prematurely reached during translation. This can yield a truncated abbreviated protein product, which quite often lacks the functionality of the normal, non-mutant protein.

By: Suman Bhattacharjee

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Nonsense mutations - Video

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