The Drosophila melanogaster, commonly known as the fruit fly, is a species of Diptera and is commonly used in biology because of its ease to study its chromosomes that resemble human chromosomes (Roberts, 1986). The fruit fly is an efficient genetic organism because they have a brief generation time, produce many offspring, have 4 pairs of chromosomes (3 autosomal and 1 sex) and their larval salivary glands display chromosomes called polytene (Hammond & Laird, 1985). The cells undergo endomitosis which is a process whereby the cells do not undergo cell division but their chromosomes duplicate. Puffs are regions in the chromosomes where RNA transcription takes place (Biology Department, 2011). The hypothesis in this lab is that the cell size of D. melanogaster in the larval salivary gland will be much larger than normal human cell because of endomitosis. I predict that the chromosomes will be long and look the same.
Materials and Method
The D. melanogaster larvae were prepared beforehand whereby their development was slowed by a decrease in temperature. I took a larva near the food source in the culture bottle and placed it in a drop of Ringers solution on the side of a slide, then placed the slide on a binocular dissecting microscope. Using a pair of forceps, I held the organism at the middle and using a sharp dissecting needle I pierced its head and gently pulled it apart. Once the head was detached from the rest of the body, I segregated the salivary glands from the fat body and placed it in a stain on the slide. After 20 minutes, I observed under a light microscope (Biology Department, 2011).