Biology Forum Genetics Genetics problem, I am stuck

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    • #13411
      jacss2
      Participant

      Hello,

      I want to study the inheritance of red eyes and white eyes in drosophila.
      I have mated red-eyed females with white eyed males.

      F1: F1: All F1 females were white eyed and all F1 males were red-eyed.
      19 white eyed females and 22 red eyed males.

      I have also crossed the females and males of the F1 generation, but this is not relevant for my question.

      I am trying to draw a pedigree chart for the P generation and their offspring, but there is a small problem. I know that this trait is sex-linked, and that the white eyes allele is recessive. Let R denote the red eyes allele and r the white eyes allele. Here is what I get:

      Can someone please explain me the problem.
      Thank you very much

    • #100091
      JackBean
      Participant

      why the mother can’t be heterozygous?

    • #100097
      jacss2
      Participant

      Hello

      The teacher told us the females of the P generation is homozygous. However, maybe she was wrong. I guess you are saying this because it is impossible to get these data without the mother being heterozygous?

    • #100110
      JackBean
      Participant

      well, you could come up with some mutation or gene expression alteration… but that had to occur already in mother’s ovaries or what do flies have, as all offspring is the same

    • #100153
      fastsandslash
      Participant

      Yes, the only way apart from mutations, would be a heterozygous mother since the male has only a recessive r, and the female must have another recessive r (as a female offspring has rr=red eyes), thus, the genotype of the mother must be Rr or else there will be no recessive phenotyped children. (add punnet square here)

    • #100745
      zuzike
      Participant

      Hi, maybe there is problem with cultivation temperature. There has been one experiment in Swiss, where drosophila eggs were cultivated in different temperature and the color of their eyes has changed.

    • #101408
      jasmine25
      Participant

      Can anyone explain me the problem of red eyes and white eyes

    • #101416
      JackBean
      Participant
      quote zuzike:

      Hi, maybe there is problem with cultivation temperature. There has been one experiment in Swiss, where drosophila eggs were cultivated in different temperature and the color of their eyes has changed.

      yeah, I think some silencing… however, question is, whether it would occur in all females?

    • #101468
      zuzike
      Participant

      JackBean: Sa mi zda ze tam sa jednalo o epigeneticku zmenu. A nepamatam sa, zeby hovorili o nejakych pomeroch, ale skor, ze sa to stalo u vsetkych.

    • #101470
      JackBean
      Participant

      však jo, silencing je epigenetická změna způsobená třeba methylací, ať už v promotoru nebo v kódující oblasti.

      A pokud to bylo dáno podmínkami, tak je logické, že toho dosáhli u všech. Jenže to nevysvětluje, proč chlapáci měli červený oči 😉

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