Title: A true breeding vestigial-winged female was crossed with a true breeding... Post by: Sara on Oct 7, 2010 A true breeding vestigial-winged female (vg vg, ri+ri+) was crossed with a true breeding male fly with incomplete wing veination (vg+vg+,ri ri). All the F1 progeny were wild type. The F1 flies were allowed to interbreed and the table overleaf shows the phenotypes of the F2 generation
Phenotype Number Wild type 552 Vestigial wing 284 Incomplete wing vein 173 Explain why there are only three visible phenotypes rather than four. What is this phenomenon called? Cross 7 Starting from the parental cross shown below, write out the genotypes, phenotypes and sex of the F1 progeny and fill in the Punnett square to show the genotypes, phenotypes and sex of the F2 progeny. Note that X = the X chromosome and Y = the Y chromosome. Parental vg vg, Xw+Xw+ x vg+vg+, XwY Vestigial-winged female White eyed male F1 Genotypes = F1 Phenotypes = F1 Sex = F2 Genotypes, phenotypes and sexes displayed in a Punnett square What is unusual about the phenotypic ratios shown in this F2 and what is the cause of this effect? Do the alleles of the white gene segregate independently of the vestigial gene? Title: A true breeding vestigial-winged female was crossed with a true breeding... Post by: sarah! on Oct 7, 2010 For Cross 7:
Xw Y Xw+ Xw+Xw Xw+Y Xw+ Xw+Xw Xw+Y Vg+ Vg+ Vg Vg Vg+ Vg Vg+ Vg Vg Vg+ Vg Vg+ The Red colour indicates the males. For your F2 cross, you will take Vg Vg+ crossed with Vg Vg+ AND Xw+Xw crossed with Xw+Y. Oh, and it would help if you told us what textbook you're using. Title: A true breeding vestigial-winged female was crossed with a true breeding... Post by: Sara on Oct 8, 2010 For Cross 7: Xw Y Xw+ Xw+Xw Xw+Y Xw+ Xw+Xw Xw+Y Vg+ Vg+ Vg Vg Vg+ Vg Vg+ Vg Vg Vg+ Vg Vg+ The Red colour indicates the males. For your F2 cross, you will take Vg Vg+ crossed with Vg Vg+ AND Xw+Xw crossed with Xw+Y. Oh, and it would help if you told us what textbook you're using. Sorry i am using Essential Genetics, a genomics perspective Title: A true breeding vestigial-winged female was crossed with a true breeding... Post by: Biology Forums on Oct 8, 2010 For Cross 7: Xw Y Xw+ Xw+Xw Xw+Y Xw+ Xw+Xw Xw+Y Vg+ Vg+ Vg Vg Vg+ Vg Vg+ Vg Vg Vg+ Vg Vg+ The Red colour indicates the males. For your F2 cross, you will take Vg Vg+ crossed with Vg Vg+ AND Xw+Xw crossed with Xw+Y. Oh, and it would help if you told us what textbook you're using. So your F1 should look like: Vg Vg+ Xw+Xw Vg Vg+ Xw+Y Vg Vg+ Xw+Xw Vg Vg+ Xw+Y |