Drosophilia Lab Report

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Introduction Drosophila melanogaster’s life cycle has four stages: egg, larva, pupa, and adult. When the egg is laid the larva hatches within twenty-four hours and goes through two molting periods. The growth stage before and after the molting periods are called instars. After the third instar, the puparium develops, which is where metamorphoses takes place. This is when one can see the pigment of the eyes and folded wings. In a few hours of the completion of metamorphosis, the fruit flies will get rounder in the abdomen, darker in color and will extend its wings. In about fourteen days fruit flies will reproduce to adults and once adults’ females may start laying eggs within forty-eight hours. It is important to use virgin females for genetic crossing since they can store sperm after one insemination and use it to reproduce multiple times (Woodrow). With genetic crossing one will observe the phenotypic, the physical observation, received from the genotype, genetic make-up of organism. Genotypes consist of chromosomes. Chromosomes are found in the cells which organize the structure of DNA and protein. It is a single strand of DNA that contains many genes and other nucleotide sequences. A gene is a region that can be located in the genomic sequence that corresponds to a unit of inheritance; it is instructions that consist of alleles (Wikipedia). An allele can make different phenotypic traits appear, such as eye color in fruit flies. The eye color, red, may show up because of homozygote, same allele- AA, aa; or heterozygote, different allele – Aa. Dominant, A, will appear regardless of the heterozygote allele. Recessive gene shows up if it is homozygote, aa. The main objective of the lab is to observe and predict the hereditary traits in fruit flies and the use of Punnett squares to predict the phenotypic and genotypic ratio of wild type (normal) and mutated flies.

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