Read the following passage carefully about some aspects of genetics involving a certain species of Drosophila and then answer the following questions in parts The gene for the production of eye colour in this species of fruit fly can be expressed as either normal red-eyes or as brown-eyes. The allele for the normal red eyes is dominant to that of brown, and is transmitted in normal Mendelian fashion. A gene involved with body colour in this species of fruit fly is located on the non-homologous portion of the X chromosome, and has two alleles, grey and yellow, where
Read the following passage carefully about some aspects of genetics involving a certain species of Drosophila and then answer the following questions in parts
The gene for the production of eye colour in this species of fruit fly can be expressed as either normal red-eyes or as brown-eyes. The allele for the normal red eyes is dominant to that of brown, and is transmitted in normal Mendelian fashion.
A gene involved with body colour in this species of fruit fly is located on the non-homologous portion of the X chromosome, and has two alleles, grey and yellow, where the grey allele is dominant to yellow.
The two genes are NOT linked.
- a) Produce a key to clearly show the nature of the alleles associated with the eye colour in this species of Drosophila, and in each case justify your choice of letters and / or style of presentation to best depict the genetics involved.
- b) State the type of genetics involved in terms of body colour, justifying your answer with the evidence from the question details given.
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Question 1 continued…
- c) Produce a key to clearly show the nature of the genetics associated with this Drosophila species body colour, and in each case justify your choice of letters and / or style of presentation to best depict the genetics involved.
- d) A red-eyed female with a grey body is crossed with red-eyed male with a yellow body – without further information and using the information you have provided in your keys in parts B and D, what are the possible genotypes of these two flies and why?
(Hint: You need to show the genotypes as an expression of both genes together -
and you need to explain the logic of how you have arrived at your answer -
NO genetic proofing / diagrams such as Punnet squares required at this stage).
f) Having identified the genetic identity of the parent flies, fully proof your answer to show the simultaneous transmission of the two genes involved to give rise to the progeny given in part e), with the use of genetic diagrams and summaries as required. (Hint: you are only required to show the simultaneous transmission from the P to F1 generations)
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