Introduction: The purpose of this lab was to figure out which mutation in parental male Drosophila melanogaster caused the bright red phenotype. This was done by linkage analysis. The D. melanogaster is commonly known as a fruit fly. The Drosophila is a model organism meaning the organism is ideal for studying genetics due to its short lifespan and ease of care. The Drosophila life cycle can be completed within two to three weeks. The life cycle starts as an egg and goes through three instar phases. Next, it becomes a pupa before it matures into an adult. Male and females then mate and the female lays eggs, starting the cycle over again (Herman 2017). Drosophila are also great model organisms because their entire genome has been studied and …show more content…
There are three recessive mutations that block the synthesis of the brown pigment in the eye, causing a bright red coloration. The red eye mutations are called vermilion (v), cinnabar (cn), and scarlet (st) (Herman 2017). Another recessive mutation blocks the red pigment synthesis, brown (bw), causing a brown eye color. If both bw and at least one of the red mutations interact the eye has no pigmentation and is white (Herman 2017). Another recessive mutation that has been studied and that will be utilized in this lab is the vestigial wings mutation, called vestigial (vg) (Herman 2017). This causes the wings to be shriveled and not work …show more content…
The vermilion gene is sex linked causing the expected ratio to be 3 brown-eyed, wild-type wings: 1 brown-eyed, vestigial: 3 white-eyed, wild-type wings: 1 white-eyed, vestigial for males and 3 brown-eyed, wild-type wings: 1 brown-eyed, vestigial for females. The scarlet gene independently assorts causing a 9:3:3:1 ratio for both males and females. The cinnabar gene is on chromosome 2 which is also where brown and vestigial are located. This causes a 2:1:1 ratio for both males and females and there are no flies with both white eyes and vestigial wings. The presence of white-eyed vestigial flies would seem to make cinnabar not an option. However, counting white-eyed vestigial flies was most likely do to human error. The flies with that phenotype all came from a vial that had lower viscosity food. This caused some wild-type wings to be stuck together and look as if they were vestigial. All other vials with solid food did not have any white-eyed vestigial