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Ch. 21 - Genomes and Their Evolution
Chapter 21, Problem 4d

(d)Primates and rodents diverged about 65 million years ago, and chimpanzees and humans diverged about 6 million years ago (see Figure 21.17). How many amino acid differences are there between the sequence for the mouse and the sequence for the chimpanzee, gorilla, and rhesus monkey? How many amino acid differences are there between the human se-quence and the sequence for the chimpanzee, gorilla, and rhesus monkey? Based solely on the numbers of amino acid differences occurring over these time periods, what might you hypothesize about the rate of evolution of the FOXP2gene? Based on the information in the chapter regarding the FOXP2 gene, is your hypothesis correct?

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Identify the amino acid sequences for the FOXP2 gene in each of the species mentioned: mouse, chimpanzee, gorilla, rhesus monkey, and human. This data is typically obtained from a genetic database or published research.
Align the amino acid sequences of the FOXP2 gene from each species using a sequence alignment tool. This step is crucial for accurately comparing the sequences and identifying differences.
Count the number of amino acid differences between the mouse sequence and the sequences of the chimpanzee, gorilla, and rhesus monkey. Record these differences separately for each comparison.
Similarly, count the number of amino acid differences between the human sequence and the sequences of the chimpanzee, gorilla, and rhesus monkey. Again, record these differences separately for each comparison.
Analyze the number of differences in the context of the evolutionary time scale provided (65 million years for primates and rodents divergence, and 6 million years for chimpanzees and humans divergence). Hypothesize about the rate of evolution of the FOXP2 gene based on these differences, and consult the chapter information on the FOXP2 gene to see if your hypothesis aligns with established findings.

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Key Concepts

Here are the essential concepts you must grasp in order to answer the question correctly.

Molecular Evolution

Molecular evolution refers to the process of evolution at the scale of DNA, RNA, and proteins. It involves changes in the genetic material over time, which can lead to variations in amino acid sequences among different species. Understanding molecular evolution is crucial for analyzing the genetic differences between species, such as mice and primates, and for inferring evolutionary relationships based on these differences.
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FOXP2 Gene

The FOXP2 gene is associated with language and speech development in humans and is known to have undergone significant evolutionary changes. It is often studied in the context of its role in neural development and its differences across species. Analyzing the amino acid differences in the FOXP2 gene among species can provide insights into the evolutionary pressures and adaptations related to communication and cognitive abilities.
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Molecular Clock Hypothesis

The molecular clock hypothesis posits that genetic mutations accumulate at a relatively constant rate over time, allowing researchers to estimate the time of divergence between species based on the number of genetic differences. This concept is essential for hypothesizing about the rate of evolution of specific genes, such as FOXP2, by comparing amino acid sequences across species and inferring evolutionary timelines.
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