Why is mtDNA referred to as a molecular clock?2018 Atomi QuestionA(Choice A)It replicates in synchrony with the cell cycleB(Choice B)We use it to estimate the age of individualsC(Choice C)Alterations in mtDNA occur irregularlyD(Choice D)We use it to estimate the date that different species diverged
Question
Why is mtDNA referred to as a molecular clock?2018 Atomi QuestionA(Choice A)It replicates in synchrony with the cell cycleB(Choice B)We use it to estimate the age of individualsC(Choice C)Alterations in mtDNA occur irregularlyD(Choice D)We use it to estimate the date that different species diverged
Solution
The term "molecular clock" is used to describe mtDNA because it allows scientists to estimate the time of divergence between different species (Choice D). This is possible because mutations in mtDNA occur at a relatively constant rate over time. By comparing the mtDNA of different species, scientists can estimate how long ago the species diverged from a common ancestor. The more differences in the mtDNA between two species, the longer ago they likely diverged. Therefore, mtDNA serves as a kind of "clock" that provides information about evolutionary history.
Choices A, B, and C are incorrect. mtDNA does not replicate in synchrony with the cell cycle (Choice A), it is not used to estimate the age of individuals (Choice B), and alterations in mtDNA do not occur irregularly (Choice C). Instead, these alterations or mutations occur at a relatively constant rate, which is why mtDNA can be used as a molecular clock.
Similar Questions
Why is the use of a molecular clock controversial?Multiple choice question.It does not incorporate information from the fossil record about the timing of evolutionary events.It assumes that DNA divergence rates are constant over time.It is only useful in some species.It assumes that rates of evolution are different for different genes.
A(n) clock uses differences in DNA to determine when organisms diverged from a common ancestor.
Select all that applySelect all of the following that are true about molecular clocks.Multiple select question.They use the mutation rate of genes to determine the time of divergence from a common ancestor.They can be used to predict when new species are going to form in the future.They can be used to estimate when humans and chimps diverged from a common ancestor.They can be used in absolute dating of fossils.
What is the main assumption behind the idea of a molecular clock?Multiple choice question.A constant rate of evolution of a moleculeA constant radioactivity rate in fossilsThe presence of a stable molecule that does not change over timeA constant rate of breakdown of an unstable molecule over time
Apply the molecular clock concept to the data in the table below. Explain which of the three species in the table shared the most recent common ancestor with the human species.
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