Thursday, May 15, 2008

FF 5, Embryo 2

The concentration of molecules in the fruit fly embryo determines the "switch" of the DNA to produce specific proteins at specific places that will become the adult parts of the body. There are 4 major molecules from the mother which start the process. The book "Developmental Biology" by Scott Gilbert, published by Sinaur (6th ed.) describes it in Chapter 9 (section 2). These molecules in turn produce four proteins which continue the process. The molecules of RNA start from the mother cells in the front of the embryo and diffuse toward the back. The diffusion rate of the molecules is critical to the development of the embryo. The DNA of the new embryo can discriminate the concentration of the molecules of protein made from these mother RNA molecules. It does this by the code in the DNA in sets of genes that detect strong and weaker concentrations. A link to the fruit fly embryo picture here is from the book mentioned above.

The bicoid gene in the fruit fly is involved in the development of the embryo. The sequencing of bicoid has been done and can be obtained on the FlyBase website. A part of the graph is pictured below.

This graph tells where the gene is on the chromosome. The DNA lines up on separate strands in the organism, and the fruit fly has 4 pairs of these, while humans have 23 pairs. In the next entry I will show the sequence of the gene.

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