DNA sequencing is the process in which scientists find the sequence of the building blocks of a strand of DNA. Those building blocks in each strand are called nucleotides, each of which is assigned a letter; A (Adenine), C (Cytosine), G (Guanine), and T (Thymidine). Each strand of DNA is a double strand and are contained within cells. Each time a cell splits, so does a strand of DNA. Each single side of the strand will then replicate itself. During this replication, another completed double strand of DNA is formed, which is an exact replica of the first.
The DNA sequencing is what pre-determines the genetics of every living thing. Each gene has its own unique strand of DNA sequencing. Scientist are able to determine the exact DNA sequencing of certain genes by taking a tiny strand and putting the sequence into a computer, which can produce a 3D model of the gene. You cannot go out and purchase a DNA sequencing kit like you can buy a bottle of cologne, but through government grants and funding, the scientists who study DNA sequencing are able to use this technology to determine what goes wrong with a gene that causes diseases and deformities.
Almost everything that is alike has the same DNA sequencing except for a few small genes that determines their minor differences. Humans, for example, will have the same genetic makeup as their ancestors, apart from the small genes that give them a different hair color or shape of their ears. This is why we tend to look like our parents and grandparents, because we have mostly the same DNA sequencing as they do. This is also how DNA sequencing is used to determine paternity.
DNA sequencing is done by scientists in a very precise manner. First the DNA must be extracted from the chromosome that houses it, and then broken up into smaller strands. Each small strand is used to make a set of fragments, each one base (two opposing nucleotides in a strand) shorter than the one before it. The fragments are separated by a gel and then a fluorescent dye is used to identify each individual type of nucleotide. A computer program then generates the sequences of the nucleotides into units of about 500 bases that exactly replicate the strand that the DNA was taken from. These units are then replicated to make a very long strand of DNA sequencing. The resulting DNA sequencing is then shared with other scientists in computer databases.