blues 3 years ago Right biology, are you ready for a challenge?

1. blues

A genetics student has a problem: Many, many matings between many, many white eyed flies produces only white eyed flies. Many matings between yellow eyed flies produces approx 1/3 white and 2/3 yellow eyed flies. Many mantings between brown eyed flies produces exactly 1/3 white, a little less than 2/3 brown and a very few yellow eyed flies. A single cross between a yellow eyed fly and a brown eyed fly produces roughly 2/3 brown eyed and 1/3 white eyed offspring. A cross between two of the F1 brown eyed offspring produces 1/3 white eyed offspring, 1/2 brown eyed offspring and 1/6 white eyed offspring. A cross between one of the F1 brown eyed and F2 white eyed offspring produces 1/2 white eyed offspring, 3/8 brown eyed offspring and 1/8 yellow eyed offspring. What genetic relationships control eye color in flies? What were the genotypes of the yellow eyed and brown eyed flys in the first cross? Try this and you will win the respect of the group; solve it and you will win eternal glory. The answer will be posted on Sunday evening EST. All the best of luck!

2. Preetha

Blues, fabulous.

3. Preetha

See the Broadcast announcement, I just posted your challenge and tweeted it!

4. blues

I did see it! I really want people to take a swing at it. I'll be happy to answer questions and lend encouragement to anyone who takes a crack at it.

5. Preetha

Good, we like these kind of challenges. Lets see what happens.

6. sasogeek

challenge challenge! :D i'm studying genetics in school now so trying my hands on it will be awesoooomeee! but right now i gotta go to school so will take it to school and see if i cal solve it while there :)

7. sasogeek

i think you meant 1/6 yellow eyed offspring :)

8. heena

the relation between eye colour is yellow is dominant over brown and brown is dominant over white the genotype of F1 is Yb x bW <y=yellow,b=brown ,W=white> Yb is genotype of yellowed eye and bW is genotype of white i guess as i didnt study it yet but i done this chapter in 10 std hope so it should be like dis but i like ur ques its awesome... :P new thing for me

9. sasogeek

1. Genetic relationship controlling eye color in flies: Brown eye color gene is dominant over white and yellow eye color genes. White eye color gene is dominant over yellow eye color gene. let B be brown eye gene, w be white eye gene and y be yellow eye gene. B>w>y 2. Genotypes of yellow and brown eyed flies in first cross: genotype for brown eyed fly - Bw genotype for yellow eyed fly - yy

10. blues

First of all, thank you all for looking at the problem and for trying! The one gene/three alleles hypothesis is a good guess, but it breaks down when you try to work through the data from the many flied experiments. If b > w > y, then how could yy x yy crosses between yellow flies result in white eyed offspring?

11. blues

@ heena, I am certainly open to making this the first of a regular weekly bio challenge. I am also open to listing possible subjects you all would like the question to be on and writing the question on the most populat. Or we could all take turns asking the weekly challenge. But before I do that, I would definitely like approval from the moderators. It is their site and there is a big difference between posting an interesting genetics question and making a major addition to the site.

12. heena

well i m wid u but i ll join this after 5feb but ask it as it once sounds great :)))

13. blues

I think it would be a great idea for everyone to work with each other on this problem, too...

14. heena

hey is my ans is right??

15. blues

No, it isn't. As clearly as I can tell, you have one gene with three different alleles and that's not correct.

16. heena

but yellowed eyed can have YW gene qand brown can have bW gene when we cross we can get that

17. blues

I think you should read the chapter on genetics again. Sorry, ;D.

18. heena

well still i dint studied chapter gentics as this year i ll i wrote the ans as i said from previous knowledge wen we are first intoduce to medels law :)

19. sasogeek

well i didn't state this earlier, but let me put it this way this time. let B, Y, and W be dominant brown, yellow and white eye color genes, and b, y, and w be recessive brown, yellow and white eye color genes. a Yw x yy cross will result in yellow and white eyed flies maintaining that w>y

20. blues

8:00 at night, Eastern Standard Time.

21. sasogeek

the brown parent has brown dominant and yellow recessive, and brown dominant and white recessive... if that's what u mean... By and Bw

22. heena

wats wrong in my equation too plz ans dat

23. sasogeek

2 genes, 2 alleles each, By, By | wy, wy ...

24. heena

as here it is said that brown eyed mates many many times so the genotype can be bW x bY and it fulfils the condition now yelloes eyes YW x YW its also fills the condtion acc. to ur ques now by crossing both bW x YW <F1> it also fills condition and i think variation occurs isntd..??

25. sasogeek

a cross between bW and bY won't satisfy the fractions of the offspring produced

26. sasogeek

well that still doesn't fit in well... check ur crossing again

27. heena

which one??

28. sasogeek

bY x bY

29. heena

yeah rit hold on i think i made a mistake in copying as i did dat ques at afternoon lemme see just a sec to make it correct

30. sasogeek

blues is it possible to have 3 genes controlling the same trait but with different characters on the same allele? so that we can have Byw on the same allele?

31. heena

listen the gene i correcterd is bY X bW as there is three cooured eye lid is occuring now its filled the condition

32. heena

as u are saying that my equation is wrong in that case this statement cant be possible den "Many mantings between brown eyed flies produces exactly 1/3 white, a little less than 2/3 brown and a very few yellow eyed flies."

33. sasogeek

that is possible, i tried that crossing to day and it satisfied the fractions... that is a valid statement

34. heena

den u cant say wrong to mine becoz its too fvalid on my equation and as i stated above the relation between eye colour is yellow is dominant over brown and brown is dominant over white the genotype of F1 is Yb x bW <y=yellow,b=brown ,W=white> Yb is genotype of yellowed eye and bW is genotype of white

35. heena

can u show me ur work saso so i can undrstand more fast abu incorrection of mine one

36. heena

blues say abu mine one too.. as i knw that there will no sense to discuss me on this as i didnt studied but as previous knolwedge i think it might be true

37. sasogeek

heena take a look at the picture and work out the fractions... it works just fine :)

38. heena

is three allele can be posiible??

39. heena

i dint studied dunno so is it possbile and plz also mention the dominancy acc. to u

40. sasogeek

that's not 3 alleles..... that's 3 genes. and about the dominancy, B is dominant over both white and yellow. white is dominant over yellow. the many matings between brown eyed flies is what i've shown in the table, the parent brown that were mated to get brown, yellow and white in the given proportions are what i've shown in the table.

41. heena

k den if u mate brown eyes and yellow u wont get t F1 by fliing its condition have u solved furtherr/?

42. sasogeek

what do u mean?

43. heena

i mean there is a ques dat A cross between one of the F1 brown eyed and F2 white eyed offspring produces 1/2 white eyed offspring, 3/8 brown eyed offspring and 1/8 yellow eyed offspring. What genetic relationships control eye color in flies? What were the genotypes of the yellow eyed and brown eyed flys in the first cross?

44. heena

just one ques F1 means first generation of yellowed eyes and F2 means first generation of brown eyes rit

45. sasogeek

F1 brown eyed = first generation of brown eyed flies F2 white eyed = second generation of white eyed flies

46. heena

hmm.. den my ans is wtrong if F1 and F2 means this i ll make a chart again :P

47. sasogeek

1.Genetic relation ship that controls the eye color in flies: let B, Y, and W be dominant brown, yellow, and white eye color gene respectively and let b, y, and w be recessive brown, yellow, and white eye color gene respectively. if x>y implies that x is dominant over y, then; B>w , B>y , B>b , W>b , W>y , W>w , Y>b , Y > w , Y>y , w>b , w>y , b>y 2. Genotypes of brown and yellow eyed flies in first cross: Brown (BB and Bw) and Yellow (yy)

48. blues

First of all, thank you to those who tried this problem! Saso posted one correct solution with three different genes of one allele each with brown > yellow > white. For details, see his answer. As promised, he wins eternal glory. While his solution is compatible with the way the problem was worded, it was not the solution I had in mind when I came up with the problem.