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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A nucleotide-pair substitution
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A mutation that changes one amino acid to another.
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Insertions or deletions that are not a multiple of three.
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A mutation that changes an amino acid codon to a stop codon
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Detailed explanation-1: -Frameshift mutations occur when the coding region of a gene is altered by addition or deletion of a number of base pairs that is not a multiple of three. The occurrence of a deletion versus an insertion type of frameshift depends on the nature of the transient intermediate structure formed during DNA synthesis.
Detailed explanation-2: -Frameshift mutations arise when the normal sequence of codons is disrupted by the insertion or deletion of one or more nucleotides, provided that the number of nucleotides added or removed is not a multiple of three.
Detailed explanation-3: -Insertion or deletion of three (or multiples of 3) nucleotides does not result in a frameshift mutation. It only results in the presence (or absence) of some amino acids in the polypeptide.
Detailed explanation-4: -An insertion or deletion involving a number of base pairs that is not a multiple of three, which consequently disrupts the triplet reading frame of a DNA sequence.
Detailed explanation-5: -A frameshift mutation is produced either by insertion or deletion of one or more new bases. Because the reading frame begins at the start site, any mRNA produced from a mutated DNA sequence will be read out of frame after the point of the insertion or deletion, yielding a nonsense protein.