CGDP - How it Works|
All organisms possess DNA. DNA provides the genetic code for all basic body functions from building proteins out of amino acids to regulating the timing and expression of various processes involved with development and growth. DNA is relatively simply: it can be thought of a as a double strand of nucleotides of which there are only four: G, A, T, and C. The two strands compliment one another: G's with C's, A's with T's.
Most DNA in an animal is found in the nucleus of the cells. This is called nuclear DNA. Animals also
have structures called mitochondria in their cells. These cellular organelles are the powerhouses
of the cell. Evidence indicates that mitcohondria were once free-living organisms that were
captured by early single-celled organisms, but not digested. Because they used to be living independently,
mitochondria have their own DNA, called mitochondrial DNA (mtDNA). In most animals, mtDNA is
arranged in a circular fashion. In snails, the mtDNA is between 14,000 and 15,000 base pairs long and encodes 15 genes.
We are concentrating on four genes: two ribosomal genes (16S and 12S) that build subunits
of the ribosome, and the cytochrome b (cytB) and the cytochrome oxidase subunit 1 (COI) genes, that code for important metabolic proteins.
In order to figure out the relationships among and within species, we compare the genetic sequence of G, A, T and C's from one animal to the others. Mutations occur in the base pairs, and because of the flexibility and redundancy of the genetic code, these changes can accumulate as populations and species diverge from one another. Follow along below as we show how we first extract the DNA, then amplify the target genes, and finally sequence the fragment.