THE MOLECULAR BASIS OF INHERITANCE
GENE MUTATION
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Question
[CLICK ON ANY CHOICE TO KNOW THE RIGHT ANSWER]
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stop codon
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wrong amino acid
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A shift in the reading frame
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The regulatory sequence being altered.
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Detailed explanation-1: -Definition. A nonsense mutation occurs in DNA when a sequence change gives rise to a stop codon rather than a codon specifying an amino acid. The presence of the new stop codon results in the production of a shortened protein that is likely non-functional.
Detailed explanation-2: -A nonsense mutation specifically changes an amino acid-producing triplet into a stop codon and leads to premature termination of protein synthesis in the ribosome.
Detailed explanation-3: -A nonsense mutation would change the first “T” to an “A”. This makes the first codon “ATC”. The corresponding mRNA segment, “UAG”, is a signal to the ribosome to stop the chain.
Detailed explanation-4: -Examples of diseases induced by nonsense mutations include: Cystic fibrosis (caused by the G542X mutation in the cystic fibrosis transmembrane conductance regulator (CFTR) Beta thalassaemia (-globin) Hurler syndrome.
Detailed explanation-5: -(NON-sens myoo-TAY-shun) A genetic alteration that causes the premature termination of a protein. The altered protein may be partially or completely inactivated, resulting in a change or loss of protein function.