destroyer 144

Discussion in 'DAT Discussions' started by pistolpete007, Jun 15, 2008.

  1. pistolpete007

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    if 36% of a population ahs blue eyes, what is the percentage of the recessive allele?

    why isnt the answer just 36% they are asking for the percentage of the recessive allele ....blue eyes are recessive allele so isnt the 36% the percentage of recessive allele?
     
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  3. You can simply say q=the percent of recessive alleles(b) and q^2=the percent of recessive homozygotes (blue eyes or bb)
    so: q^2=.36 and the sq. root of .36 = .6=q (the percent of recessive alles) or 60% recessive alleles

    You could also use the hardy weinberg equations to check and make sure that this adds up:
    Since the question tells us that 36% of the pop. has blue eyes(bb which is q^2) then we know that q^2=.36 , so q=.6
    Then use p+q=1 to get p+.6=1 and p=.4
    Now we will use the equation: p^2 + 2pq + q^2 = 1 ; to find the percent of the population that is heterozygous and divide this numer by 2 to find the percent of blue alleles in the heterozygotes and add this to q^2 (the percent of blue alleles in the recessive blue eyed pop.)

    Since the amount of blue alleles in a heterozygote is half the percent of heterozygotes we do: (2pq)/2........(2*.4*.6)/2=.24(b alleles in the heterozygotes)
    .24+.36=.60 or 60% recessive allele

    Hope this explanation clears everything up...
     
  4. osimsDDS

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    let me put this in an easy way to understand...when they say 36% of the population has blue eyes they are talking about the frequency of the recessive phenotype...a phenotype is made from 2 allels, either an A or a, can be homozygous dominant, recessive, or heterozygous...so when they say frequency they are talking about 2 alleles...

    Now they want to know what is the frequency of the recessive ALLELE...that means they just want to know 1 allele, the a allele not aa or AA or Aa...

    So you have to take the square root...

    Think of it like this 36% = aa
    But they want to know just a (1 allele), so a will equal .6 or 60%
     
  5. pistolpete007

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    that makes so much more sense thanks a lot

    so pretty much q=a and p=A and q^2=aa and p^2=AA right?
     
  6. osimsDDS

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    yea and 2pq=Aa
     
  7. pistolpete007

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    evaluate the value of p if (50/2) - (65/13) + (40/2)= p% of 80

    all the solution was did was add up the right side which equals 50 and said the answer was 50....first of all why did they add evertyhing when you have subtraction between 2 of them....and 2nd even if u were to add everything and get 50...why is the answer 50 bc...arnt we trying to find out what percent is 50 of 80?
     

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