Phenotypes and proportions

last updated by

MrMistery 16 years, 9 months ago

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- January 25, 2008 at 4:51 am #8993
  curious1234
  Participant
  I am trying to answer a question and I’m not sure how the book got the answer they have.
  If P and Q loci are 35 mu apart, and PQ / pq is selfed what is the phenotype of the progeny and in what proportion?
  I know if you cross PQ/ pq with PQ/ pq you get gamates: PQ, pq the parental and Pq pQ as the recombinants. My book says that you take 1/2(1- 0.35) to get P Q, 1/2 (1 – 0.35) to get pq and 1/2(0.35) is Pq, 1/2(0.35) is pQ.
  Why is PQ (1-0.35) when the problem states the distance between P and Q is 35mu ? Why do we calculate 1-0.35 to get 0.65 ??
  Also, for the proportion of progeny they say for example that PQ/PQ has F1 genotype of 0.1056. Where does this number come from? I have no idea what numbers they use to come up with this.
  Any ideas?
- January 25, 2008 at 5:06 am #81127
  mith
  Participant
  35 mu means 35% are recombinants therefore 65% are parental genotypes. therefore parentals percentalge
  PQ + pq = (1-0.35).
- January 25, 2008 at 5:07 pm #81155
  curious1234
  Participant
  Thanks!
- February 10, 2008 at 6:12 pm #81668
  lozerface16
  Participant
  my teacher gave me a take home test and one of the q. is
  7. A female calico cat is crossed with a male black cat. What are the phenotypes of the offspring and in what proportion?
  😯
  it makes no sence to me and the test mainly consists of q. like this one! ❗
  I do not understand..any of it!!
- February 16, 2008 at 5:08 pm #81905
  MrMistery
  Participant
  well you need to know how the gene is transmitted, and if there is complete dominance between the alleles which one is the dominant one.
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