Unformatted text preview: Introduction to the Drosophila melanogaster Drosophila melanogaster GENUS SPECIES Both the Genus and Species MUST always be underlined Genus begins with a Capital letter, while Species begins with a Lower Case letter Commonly called the "Fruit Fly" Genus contains more than a 1,000 species D. melanogaster undergoes complete metamorphosis. There are 4 Distinct Stages (25oC or 77oF): 1. Egg 1 day 2. Larva 6 days 1st instar 2nd instar 3rd instar 3. Pupa 4 days 4. Adult (Imago) 37 days Life Cycle: Distinguishing Sex:
1. 2. 3. 4. Size Female generally larger than Male Abdomen Shape Female abdomen is distended and pointed, while Male abdomen is round and cylindrical Banding Patterns Female dorsal rear portion has defined alternating light and dark bands, while Male dorsal rear portion has fused bands Sex Combs The Best Method. Only Males have them. Body Segments:
The Drosophila is Divided into 3 main body segments: 1. Head 2. Thorax 3. Abdomen Chromosomes: The Drosophila has 4 pairs of chromosomes for a total of 8 chromosomes. These chromosomes are found in the nucleus of every somatic (nonsex) cell. Chromosome Map: Symbolism: For "higher" organisms such as plants and animals, the Dominant trait is designated with a Capital Letter, while the Recessive trait is designated with a Lower Case Letter. Ex: A = Dominant trait a = Recessive trait For "lower" organisms such as insects, the Dominant &/or most common trait is called the Wild Type which is Designated as +/+, while the Recessive trait is called the Mutant Type which is designated with the abbreviation of the mutant trait. Ex: Vestigial = vg (vg/vg) Sepia = se (se/se) Dumpy = dp (dp/dp) In a given Experiment, we can consider 3 Traits: 1. Eye color of the fly (D. melanogaster) 2. Wing shape of the fly 3. Body color of the fly Wild Type Drosophila melanogaster: An adult wild type fly has Full Red Eyes, A Beige Colored Body and Full Round Wings that pass well beyond the abdomen. A deviation from any of these characteristics will be considered a Mutant for that particular trait. (Example: Ebony Colored body would be considered a mutant for body color) 1. Eye Color: * Wild Type (+): Full, Round Red Eyes Mutants:
Sepia Eyes (se): Full, Round, Brown White Eyes (w): Full, Round, White Bar Eyes (B): Irregular, Red Scarlet Eyes (st): Full, Round, Bright Red Eyeless (ey): Small, Round, Red 2. Wing Shape: * Wild Type (+): Full, Round Wings Mutants: 3. Body Color: * Wild Type (+): GrayishBeige Colored Body Mutant: Ebony Body (e) Black Colored Body ...
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- Spring '08
- Genetics, wild type, recessive trait