Type R for Regulatory gene Type S for Structural gene Type E for Epigenetic fact
ID: 149612 • Letter: T
Question
Type R for Regulatory gene Type S for Structural gene Type E for Epigenetic factor Methylation prevents the expression of distal aminos in an early mesozoic-era lizard, preventing the formation of complete legs. - A point mutation changes a codon from UAC to UAG, resulting in a stop codon. This means the protein is no longer produced. -A developmental gene duplication results in the addition of a third thoracic segment and a third set of wings in an insect species. A point mutation in a fish leads to the complete destruction of the gene coding for a-globin protein, a sub-unit of the blood protein hemoglobin.Explanation / Answer
Regulatory genes control the expression of other structural genes. So, if a mutation occurs in regulatory genes, it may lead to its non-functionality thereby causing the structural genes under the control of this regulatory gene become downregulated. The methylation of a gene sequence blocks its expression.
So, in first question,
R (Regulatory gene) - methylation prevents the expression of distal aminos in an early mesozoic era lizard, preventing the formation of complete legs.
A Point mutation in a structural gene sequence causes the change of coding frame (frameshift mutation) leading to the production of non-functional protein. Also the point mutation changing the codon to a nonsence codon (UAG) lead to the production of non-functional truncated protein (Nonsense mutation).
So, in second question,
S (Structural gene) - A point mutation changes a codon from UAC to UAG, resulting in a stop codon. This means the protein is no longer produced.
Epigenetic factors like MATERNAL GENES control the expression of other developmental genes in insect species. This is called maternal effect gene control.
So, in third question,
E (Epigenetic factor) would be the option.
And in fourth question,
S (structural gene) would be the correct anwer. (frameshift mutation).
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