Question

1. Insects are one of the most abundant and diverse groups of animals with biologists estimating that there are about 5 million species with many of them not yet described. Describe three reasons why insects such as the fruit fly have become an important model system along with snails, worms, sea urchins, frogs, chickens, zebrafish, and mice.

2. Even though the fruit fly is “just” an insect, it is an important model system for understanding human disease and development.

Describe one example of how the fruit fly has contributed to our understanding of a specific disease or aspect of development based on a quick search of the scientific literature. Limit your response to six sentences.

Answer 1

1. Drosophila is an important model organism for research due to several features such as short life cycle (12 days), inexpensive to culture and maintenance, small genome size, lower number of chromosomes and presence of polytene chromosomes (large chromosomes with light and dark banding pattern which facilitate easy identification of chromosomal rearrangement and deletion under microscope).Genetic manipulations were easier in drososphila due to the small genome size. Their short lifecycle will be useful to gey quick result.The gene sequences of man highly matches with equivalent genes in drosophila. About 75% of disease causing genes in human are also found in drososphila. Drosophila is the model organism that is used to study Parkinsons disease, Alzheimers disease etc

2.In order to study a human disease in Drosophila, the disease causing protein productis made to be expressed in the fly and the changes in the organism in mimicking the disease was observed. This procedure was succesfully used to study neurodegenerative diseases in man such as, Alzheimer's, Parkinson's diseases etc. Severity of the expression of the disease causing genes also can be noted through changes in phenotypic expression in drosophila. For eg, The amyloid precursor protein (APP) is a causal agent in the development of Alzheimer's disease. The over expression of APP i will producea blistered winged phenotypic expression in drosophila. This is due to cell adhesion in wing epithelium and it will be useful to find the enzyme associated with modification of AAP that have also a role in processing cell adhesion molecules.