Drosophila Melanogaster Lab Experiment

Topics: Drosophila melanogaster, Sex linkage, Allele Pages: 8 (2429 words) Published: June 18, 2013
Extended Experimental Investigation| May 28
2013
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Drosophila melanogaster lab experiment
Question: How do the dominant or recessive genes in particular traits in a cross between a male and female Drosophila determine the traits of its offspring? Aim: to establish whether characteristics produced from the offspring of a drosophila cross are recessive or dominant traits. Hypothesis: If certain phenotypes are expressed in the offspring from the cross of certain Drosophila, then the determination or justification of recessive or dominant phenotypes can be found. Theory review and justification of the hypothesis:

Drosophila Melanogaster are simply now generally referred as the common term “fruit fly” or “vinegar fly”. These fruit flies as we call it can give us major fields of study within biology and genetics because they are very easy to care for and breed quickly. Genetics is this science of heredity of traits pass from parent to off spring. Through this, fruit flies are excellent to work with as we are able to see many generations of the flies. In fruit fly genetics there are what we call recessive and dominant traits. The normal fly or “Wild Type” is the dominant trait, any fly exhibiting another trait or mutation has a recessive trait. If a trait is dominant it is also given an upper case letter code, although if it is a mutation or recessive it is given a lower case letter code. For example the mutant “Ebony” has a much darker shiny black body than the wild type. Thus as ebony is a recessive mutant trait it is given a lover case ‘e’. Because the wild type fly has a dominant trait, it is denoted over the mutant letter code being recessive. For example if we cross a wild type fly with an ebony body fly it will produce an offspring with a normal body colour (not ebony) because the wild type is the more dominant gene. Of course though, these traits are all carried within the sex chromosomes of the flies. In sex linked inheritance, alleles on sex chromosomes are in predictable patterns. All off spring traits is determined by the parent’s genes. A female fruit fly carries two X chromosomes as for a male has an X and a Y chromosome, this is how the sex of an organism is determined. Also these sex cells (reproductive cells) are responsible for transmitting DNA to the next generation of offspring. The phenotype (an organisms appearance or the result of the characteristics from the organisms genotypes) I have chosen to work with are Vestigial (mutant), Ebony(mutant) and Wild type. Our crosses firstly consisted of 4 vials: vial 1 consisted of Two Vestigial Flies (1 Male, 1 Female). ).vial 2 consisted of two Ebony (1 male and 1 female). If both vial 1 and vial 2’s flies are homozygous, the off spring for both flies will be a homozygous mutant. We can show this through punnet squares: Genotypes= X-v X-v, X-v Y-v, X-v X-v, X-v Y-v

= 1:1
= 1/2:1/2
Phenotypes= Vestigial Female: Vestigial Male
50%50%
Therefore the chance of the offspring being a Vestigial drosophila is 100%. The chances of it being a Vestigial male is 50% Genotypes= X-v X-v, X-v Y-v, X-v X-v, X-v Y-v
= 1:1
= 1/2:1/2
Phenotypes= Vestigial Female: Vestigial Male
50%50%
Therefore the chance of the offspring being a Vestigial drosophila is 100%. The chances of it being a Vestigial male is 50%

VILE 1
W- Wildtype
v- Mutant(Vestigial)

Genotypes= X-e X-e, X-e Y-e, X-e X-e, X-e Y-e
= 1:1
= 1/2:1/2
Phenotypes= Ebony Female: Ebony Male
50%50%
Therefore the chance of the offspring being an Ebony drosophila is 100%. The chances of it being a Ebony male is 50% Genotypes= X-e X-e, X-e Y-e, X-e X-e, X-e Y-e
= 1:1
= 1/2:1/2
Phenotypes= Ebony Female: Ebony Male
50%50%
Therefore the chance of the offspring being an Ebony drosophila is 100%. The chances of it being a Ebony male is 50%

VILE 2
W- Wildtype
e- Mutant(Ebony)

Genotypes= X-W X-v, X-W X-v, X-W Y, X-W Y
= 1:1:
= ½:1/2
Phenotypes= Wildtype...

References: . 2013. . [ONLINE] Available at: http://www.mun.ca/biology/dinnes/B2250/DrosophilaGenetics.PDF. [Accessed 26 May 2013].
Genetic Traits In Wild and White-Eyed Drosophilla. 2013. Genetic Traits In Wild and White-Eyed Drosophilla. [ONLINE] Available at: http://tolweb.org/treehouses/?treehouse_id=3778. [Accessed 26 May 2013].
Drosophila melanogaster - Wikipedia, the free encyclopedia. 2013. Drosophila melanogaster - Wikipedia, the free encyclopedia. [ONLINE] Available at: http://en.wikipedia.org/wiki/Drosophila_melanogaster. [Accessed 26 May 2013].
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