Question
Which one of the following mammalian DNA regions exhibits the highest level of sequence variation?
The correct answer is
Mitochondrial D-loop region
Mammalian DNA Sequence Variation Analysis
The question asks to identify the mammalian DNA region that shows the highest sequence variation.
Mitochondrial D-loop Region's High Variability
The Mitochondrial D-loop region is recognized for having the highest sequence variation among the given choices. Key reasons include:
- It is part of the mitochondrial DNA (mtDNA), which generally evolves faster than nuclear DNA.
- This region is non-coding and lacks stringent functional constraints, allowing mutations to accumulate rapidly over evolutionary time.
- Its high variability makes it a valuable marker for studying population genetics, evolutionary history, and individual identification.
Comparison with Other DNA Regions
The other options represent regions within the nuclear genome, which are typically under stronger evolutionary constraints:
- Homeobox transcription factor binding domains and Hox genes are crucial for embryonic development and body plan organization. Their functions require high conservation, limiting sequence variation.
- Histone protein-encoding genes are vital for DNA packaging (chromatin structure). These genes are also generally conserved across mammals due to their fundamental role.
Consequently, the mitochondrial D-loop region demonstrates significantly greater sequence variation compared to these nuclear DNA elements.
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Important Questions from Mutation
- Which one of the following mechanisms is expected to generate tightly linked genes?
- In a population, there are two morphs, A and B, which reproduce at equal rates. A mutates to B with probability $p_1$, and B mutates to A with probability $p_2$ such that $p_1 \gg p_2$ (that is, $p_1$ is much greater than $p_2$). Over time, which one of the following statements would be true about this population?
- A gene coding for a particular protein exhibits 2% DNA sequence divergence between humans and chimpanzees. However, protein sequences encoded by them are identical. Which one of the following processes explains this?
- Gene conversion can lead to which one or more of the following evolutionary outcomes?
- For a given gene there is 5% DNA sequence divergence between two species, however the protein coded by this gene has identical sequences in the two species. Which of the following types of mutations best explains this pattern in the DNA sequence?
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