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Neanderthal Hair Color The MC1R gene regulates pigmentation in humans (Sections 13.5 and 14.2), so Loss-of-function mutations in this gene affect hair and skin color. A person with two mutated alleles for this gene makes more of the reddish melanin than the brownish melanin, resu.lti.ng in red hair and pale skin. DNA extracted from two Neanderthal fossils contains a mutated MC1R allele that has not yet been found in humans. To see how the Neanderthal mutation affects the function of the MC1R gene, Carles Lalueza-Fox and her team introduced the allele in to cultured monkey cells (FIGURE 26.12).
FIGURE 26.12 MC1Ractivity. Activity is shown in monkey cells transgenic for an unmutated MC1R gene, the Neanderthal MC1R allele, or the gene for green fluorescent protein (GFP). GFP is not related to MC1R.
How did MCR1 activity in monkey cells with the mutant allele differ from that in cells with the normal allele?
To explain: The way in which the MC1R activity in the monkey cells with the mutant allele differs from that in cells with the normal allele.
Introduction: Neanderthals are extinct hominins that are the closest relatives of Homo sapiens and habituated to the Middle East, Europe, and Asia. The pigmentation in humans is regulated by MC1R. The loss of function mutation in the MC1R gene, in turn, affects the skin and hair color. The homozygous mutation of the gene results in red hair and pale skin phenotypes.
Explanation of Solution
Scientist C and her team worked on MC1R mutated form that was present only in the Neanderthals. The team incorporated the allele from Neanderthal into cultured monkey cells.
Based on the results from the experiment, a graph was plotted with the concentration of the hormone that stimulates MC1R in the X-axis and the activity of MC1R in the Y-axis. Three scatter plots were plotted: one for green fluorescent protein (GFP), one for Neanderthal MC1R allele, and one for unmutated human MC1R allele. The activity of MC1R was very high in the transgenic monkey cells when compared to the normal allele.
The MC1R activity in the monkey cells with the mutant allele was much greater than the cells that had a normal allele for MC1R.
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