Fruit Flies Lab Report

The Inheritance of Genetic Traits in Fruit Flies

Introduction: The purpose of this experiment is to learn how to culture fruit flies and to study the inheritance of traits via genetics in the fruit flies we culture.

Fruit flies are a common, small fly found around unripe or rotted fruit, hence the name (Geiger). This species of fly has commonly been used in many studies associated with genetics due to the lack of effort required to care for them, their short life cycle, and their easily distinguishable traits. A fruit fly’s life cycle starts with procreation, as most do. From there the female fruit flies lay eggs, which mature into larvae, or small worm-like immature flies, within a day. These larvae quickly progress into pupae, a small

Genes, or sometimes called alleles, are the small subunits that make up DNA and create the unique traits for each species. The type of genes that are replicated and passed down during DNA replication are called alleles and these combine when forming a new offspring to yield a new combination of traits. In most cases, alleles for a single trait are seen in pairs. The singular alleles within a pair can be classified as dominant or recessive, and whichever classification it falls under decides how the gene will be expressed. Dominant alleles are typically represented with a capital letter and they are traits that will always be expressed, regardless of the other allele it is paired with. For fruit flies the two dominant genes are tan bodies and long wings. This is why we expect to see a majority of our fruit flies exhibiting tan bodies and long wings. Recessive alleles are traits that tend to be “hidden”, or skip generations since they are not expressed unless it is paired with another recessive allele and they are often represented with a lowercase letter. These pairs of alleles can also be described as either homozygous and heterozygous. Homozygous alleles mean that both alleles are the exact same, so they are either homozygous dominant, both capital letters, or they are homozygous recessive, both lowercase letters. Heterozygous alleles means

For the first week, we simply started by taking the F1 generation of fruit flies and putting them to sleep using Flynap. We then transferred them from their culture vials to a petri dish where we used a small paint brush to sort them into two piles: males and females. We used their unique physical characteristics in order to differentiate the two genders from each other. We then created two more culture vials, filling each with a blue medium, a little bit of yeast, and some plastic mesh as well as labeling them with our initials. We then put roughly equal amounts of males and females in each culture vial to allow them to be able to procreate. Then we left the culture vials to sit for a week to allow the flies to create the next generation(F2). The next week(week two), we retrieved our two culture vials and inspected them to ensure there were newly formed larvae and pupae. We then proceeded to put the F1 generation to sleep once again using Flynap. Once the flies were fully asleep we once again poured them into a petri dish, ensuring we got as many flies out as we could without harming the culture vials in order to preserve the environment for the new F2 generation. We then killed the F1 generation fruit flies using a mixture of water and dawn dish soap to ensure there were no F1 flies left in our culture vials which could potentially skew our results. At this point, if there were still F1 fruit