Used in the study of Genetics.
Drosophila melanogaster was introduced into
the field of genetic experiments by Thomas Hunt
Morgan in 1909
Its importance for human health was recognized
by the award of the Nobel prize in
medicine/physiology to Ed Lewis, Christiane
Nusslein-Volhard and Eric Wieschaus in 1995
Why Use Drosophila Flies?
Short life span – 2 weeks
Cheap to study
Easy to keep in large numbers.
Entire Genome is known.
Life Cycle of Drosophila
Takes one day after fertilization for an
embryo to develop and hatch into a worm-
After two days larva forms a pupa.
After four days the pupa hatches into a fly.
Within 12 hours the fly is fertile.
Research on Drosophila
Used to discover that genes were related to
proteins and to study the rules of genetic
More recently, it is used mostly in
developmental biology, looking to see how a
complex organism arises from a relatively simple
There is also a great deal of interest in how
various adult structures develop in the pupa,
mostly focused on the development of the
compound eye, but also on the wings, legs and
Has 4 chromosomes.
X/Y and 2, 3, and 4th chromosomes.
165 million bases
In comparison, the human genome has
3,400 million bases and may have about
22,500 genes; yeast has about 5800
genes in 13.5 million base bases.
sequenced in 2000
As the fly larva grows, it keeps the same
number of cells, but needs to make much
more gene product.
The result is that the cells get much bigger
and each chromosome divides hundreds
of times, but all the strands stay attached
to each other.
The result is a massively thick polytene
chromosome, which can easily be seen
under the microscope.
These chromosomes have a pattern of dark and
light bands, like a bar code, which is unique for
each section of the chromosome.
As a result, by reading the polytene bands, you
can see what part of the chromosome you are
Any large deletions, or other rearrangements of
part of a chromosome can be identified, and
using modern nucleic acid probes, individual
cloned genes can be placed on the polytene
Polytene chromosomes are usually found in the
larvae, where it is believed these many-
replicated chromosomes allow for much faster
larval growth than if the cells remained diploid.
Simply because each cell now has many copies
of each gene, it can transcribe at a much higher
rate than with only two copies in diploid cells.