Different species have enormous regions of DNA that are the same or very similar
ID: 403 • Letter: D
Question
Different species have enormous regions of DNA that are the same or very similar. Humans and chimpanzees, for example, share about 98% of their DNA. We share much less of our DNA with yeast and rodents. In a general way, the percentage of shared DNA might be a means to establish a molecular clock - that is, the more DNA that is shared, the more recent was the separation of the
Different species have enormous regions of DNA that are the same or very similar. Humans and chimpanzees, for example, share about 98% of their DNA. We share much less of our DNA with yeast and rodents. In a general way, the percentage of shared DNA might be a means to establish a molecular clock - that is, the more DNA that is shared, the more recent was the separation of the "genetic" tree. And, if by accident, the changes in the DNA happened to proceed at a common rate, then one could set up a timeline as well. Would it be possible to use DNA as a molecular clock to measure the timescale of biological evolution. Explain your reasoning.Explanation / Answer
Yes, it absolutely would be, and this is a common practice. In many different organisms (including humans) researches have a good idea of the rate at which mutations arise in the genome. Keeping in mind the rate at which neutral or advantageous mutations occur (you cannot think abolut deleterious mutations because these will be selected against), you can calculate the amount of time required to accumulate enough mutations to make up all of the differences between the genomes of different organisms. By doing this, you can calculate approximately how long ago different species shared a common ancestor.
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