Question 1

What are the main physical characteristics of Drosophila melanogaster?

Accepted Answer

Drosophila melanogaster, or fruit flies, are small insects measuring 2-4 mm long and weighing about 1 mg. They have three main body segments—head, thorax, and abdomen—plus a single pair of wings and three pairs of legs. Wild-type flies display large red eyes and pale yellow or light brown bodies with black abdominal stripes. Females are typically larger than males.

Question 2

How long is the Drosophila life cycle and what are its major stages?

Accepted Answer

The Drosophila life cycle lasts approximately 2 weeks and consists of four major stages: embryo, larva, pupa, and adult. The average lifespan ranges from 60-80 days, though factors like temperature and overcrowding can affect longevity. This short generation time makes fruit flies ideal for rapid genetic experiments with large sample sizes.

Question 3

Why are fruit flies preferred as model organisms in research?

Accepted Answer

Fruit flies are excellent model organisms because they are inexpensive to maintain, easy to handle and anesthetize due to their small size, and require minimal laboratory equipment. Their short 2-week life cycle enables quick experiments with high sample numbers, as females can lay hundreds of eggs daily. Additionally, their simplified genetics with only four chromosomes and approximately 14,000 genes make genetic studies more informative than in organisms with genetic redundancy.

Question 4

What is genetic redundancy and how does it affect Drosophila research?

Accepted Answer

Genetic redundancy occurs when multiple genes control a single biological function. In mammals like mice, three gene copies may compensate when one mutates, producing no observable change. Fruit flies typically have only one gene version per function, so mutations cause detectable phenotypic changes. This limited redundancy makes Drosophila mutations highly informative for understanding specific gene functions.

Question 5

What genetic similarities exist between Drosophila and humans?

Accepted Answer

Approximately 50% of fruit fly genes are homologous to mammalian genes, sharing common evolutionary origins. More significantly, 75% of human disease-related genes have orthologs—genes with similar functions—in Drosophila. These striking genetic similarities make fruit flies invaluable for studying human development and disease mechanisms, from neurological conditions like Parkinson's disease to cardiac function.

Question 6

What laboratory conditions are optimal for maintaining Drosophila?

Accepted Answer

Fruit flies survive in temperatures ranging from 12-35°C but thrive in laboratory incubators set to 25°C with 60% humidity for ideal survival and fertility. In the lab, flies are fed a diet of cornmeal, molasses, agar, sugar, yeast, and water, mimicking the microorganisms like yeast found in ripening and rotting fruits in nature.

Question 7

What major discoveries have been made using Drosophila research?

Accepted Answer

Thomas Hunt Morgan established the chromosomal theory of inheritance using fruit flies, winning the Nobel Prize in 1933. Hermann Muller discovered X-rays induce mutations, earning the 1946 Nobel Prize. Lewis, Nusslein-Volhard, and Wieschaus identified genes controlling embryonic development and body segmentation, winning the 1995 Nobel Prize. Jules Hoffmann's work on innate immunity and Toll receptors earned the 2011 Nobel Prize.

An Introduction to Drosophila melanogaster - Assessment Quiz