Question

A molecule that can be used as a molecular clock has a neutral mutation rate of one mutation per 5 million years. How many years ago did two species share a common ancestor if the molecules found in these two species differ by a total of eight mutations?
1.5 million years
10 million years
40 million years
20 million years

Answer 1

20 million years ?

Answer 2

20 million years ?

Answer 3

4 mutations each, 4x5 = 20 million years!

Answer 4

Thank you ! @redbeardd

Answer 5

@beamarie just so that no one else is confused I can explain more.

the two organisms are a total 8 mutations away, and each mutation occurs 5 million years apart.

Than that means each organism has incurred 4 mutations.

We know that its not the case that only 1 organism acquired 8 mutations because that would take 40 millions years, and in 40 million years the other organism would also acquire 8 mutations on its own.

make sense?

Answer 6

Yes thank you can I ask you another question ? I got it wrong but I don't know what I did wrong. @redbeardd

Answer 7

@ashhhrodriguez of course, go ahead

Answer 8

A certain segment of DNA can be used as a molecular clock. Its rate of mutation is one mutation per 15 million years. Examine the DNA segments from two different species:

Species A: GTTGAGCTAGTATGGACC
Species B: GATAAGCTAGTAAGGTCA

Answer 9

And I got this;
5base pair mutations × 20million years/ 1 mutation = 100 million years of evolution
100 million total years of evolution ÷ 2 species (or lineages) = 50 million years of evolution from a common ancestor
but he said I miscounted my base pair mutations.

Answer 10

@redbeardd

Answer 11

I counted 5 mutations, but did you multiply by 20 millions years or was that a typo?

Answer 12

nevermind is 6 errors:

Answer 13

i mean mutations

Answer 14

Really there are 6 ? I counted so many times!

Answer 15

yeah me too, lol.

Species A: G T T G AGCTAGTA T GG A C C
Species B: G A T A AGCTAGTA A GG T C A

Answer 16

also, make sure you multiply by 15 and not 20

Answer 17

Oh I don't even know what I was doing or how I got 20 ? Thank you thank you so much!!!! @redbeardd

Answer 18

yeah no problem, but I'm counting 5 mutations again. I can't do this lol

Answer 19

Maybe what he meant was my error with the 20. Cause I only count 5 too that only makes sense

Answer 20

do you get immediate feedback on your answer?

Answer 21

So my final answer will be 37.5 million years correct ?

Answer 22

right

Answer 23

Ok thank you ! Haha no I wish but I'll let you know what he says when he does. Thank you again!!

Answer 24

ok good luck! no problem

Answer 25

@redbeardd yes, that makes sense, thank you! :)