Question

Suppose a segment of mitochondrial DNA (mtDNA) is compared between two similar modern-day species. It is known that this segment of mtDNA changes at a steady rate of one base pair every 4 million years. Compare the sequences of the two mtDNA segments given below.

Species A: GCACTAAGCATCGATTT

Species B: GCACCAGGCACTGGTTC

Use this base principle of molecular clocks to calculate how long ago the two species diverged from a common ancestor.


A) 12 million years ago
B) 8 million years ago
C) 48 million years ago
D) 24 million years ago

Answer 1

Answer: 12 Million Years Ago

Explanation:

1. Base pair mutations × million years = years of evolution

2. Million total years of evolution ÷ # of species (or lineages) = million years of evolution from a common ancestor

1. 6 base pair mutations x 4 million years = 24 million years of evolution

2. 24 million total years of evolution ÷ 2 species = 12 million years of evolution from a common ancestor

Answer 2

24 million years long ago mitochondrial DNA (mtDNA) of species A having segment GCACTAAGCATCGATTT and that of species B having segment GCACCAGGCACTGGTTC diverged from a common ancestor.

What do you mean by mitochondrial DNA (mtDNA)?

• "Mitochondrial DNA is the circular chromosome found inside the cellular organelles called mitochondria."
• Functions of mitochondrial DNA include- regulation of cellular metabolism and apoptosis(cell death).
• The mutation in mtDNA is high.

What do you mean by diverged?

• "The situation in which two things become different."

The two samples of species are-

Species A -  GCACTAAGCATCGATTT

Species B -  GCACCAGGCACTGGTTC

There are 6 base pair changes in mitochondrial DNA of both species.

As we know that change in 1 base pair takes = 4 million years

So, the change in 6 base pair takes = 4 x 6 million years

                                                             = 24 million years.

Hence, option D. 24 million years ago is correct.

To know more about mitochondrial DNA here

https://brainly.com/question/508534

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