Tricky Hardy-Weinberg problem

[@MJ-98]

for the third time, nikolay's genetic lessons have saved my grade.

[@GeneticsLessons]

Glad I could help.

[@sarahlawhun8989]

Excellent tutorials, thank you for what you do!

[@GeneticsLessons]

Glad you like them!

[@sarmadghafoor1484]

Just want to thank you for helping me in uni :D my teacher didn't explain it well and was very brief in his explanation TYVM

[@rashmisahoo2410]

very difficult to understand if u will watch one time

[@GeneticsLessons]

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[@dechante6696]

Thank you for this video I understand it a bit better now as I am struggling with a question I got given. I got given a question where 6 females are colourblind, 110 females are not, 12 males are colourblind and 74 males are normal. I have been told to work out the number of female carriers but I am not sure whether I am meant to work out females separately or take males into account. Am I meant to work out q for males and females separately then work out the sum or do I just use females in HW?

[@GeneticsLessons]

This problem wrong by itself. Here is calculations: occurrence of the defective X chromosome in this population is 12/86 or 0.14 So occurrence of the colorblind women should be 0.14x0.14= 0.0196 116x0.0196=2.27 but we have 6 effected women. Due to the small sample this problem has no solution.

[@dechante6696]

@@GeneticsLessons Oh okay thank you! I'm just confused on this question because of the fact this is on one of my assignments and it's worth 4 marks so I am just confused to how there is no solution. This is my working out but idk if it is correct Recessive homozygous females= q squared= 6/200 so q=0.173 Homozygous males= q= 12/200 (0.06) Summed frequency= 0.233 so 1-q=p 1-0.233= 0.767 p=0.767 Number of alleles in population is 316 so there are 242 normal alleles and 74 colourblind alleles 6 females are recessive so there are 12 alleles and there are 12 males so 12 alleles so 24 of the 74 alleles are colourblind so therefore there are 50 carriers

[@dechante6696]

@@GeneticsLessons Can I also ask why you have to work out the allele frequency of the colourblind males over the colourblind females even if the question asks me to find out the number of female carriers and gives me female data unlike the example given in the video?

[@GeneticsLessons]

One second you first state 6 color blind women and 110 normal, than state 200 normal - how come - this change everything.

[@GeneticsLessons]

No, frequency of effected males directly reflects frequency of defective X chromosomes in this population: 12/86=0.14 Because males have only one X chromosome. Please check your numbers, maybe you gave me wrong numbers?

[@jordiecartier]

It isn't clear whether the 14.72% is answering a or b and what the other answer is

[@GeneticsLessons]

Watch again starting from the minute 10:00

[@gracefisher2446]

Thank you :)

[@GeneticsLessons]

Welcome!

[@christophe453]

Thank you!!

[@sarahwood3076]

Hi, I am confused about why you multiply 0.08 to find the frequency of females who are colourblind? If 8% of males are colourblind, and this is the frequency of only one X allele in the population, wouldn't you multiply it by 3 for the two chromosomes of the female?

[@genas6703]

Late reply but because the frequency of an affected male is 8%, the frequency of an affected X chromosome is 8%. However, female have two X's so the probability is 8% x 8%

[@GeneticsLessons]

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[@nourtohamy143]

thank u!

[@ghsjgsjg53chjdkhjydhdkhfmh74]

10:37

[@GeneticsLessons]

Watch my new video what is Dominant Epistasis? kzbin.info/www/bejne/m6eZcnusnqxkq6M