Genome is the scientific term used to describe all the known hereditary information stored within a species, usually within its DNA though sometimes in RNA. Such genetic information can be expressed or non-expressed and epigenetics comes into the picture. The human genome contains 3 billion 'letters' (G, T, A and C, representing the four chemical bases of DNA)
Eukaryotes in all species include both chromosomal material (information contained in the chromosomes found in the cell's nucleus) and mitochondrial material (information found in the mitochondria inside the cell's cytoplasm).
Genomes, evolution and creationism
Genome sequencing is one of the more important pieces of evidence for evolution. Evolution predicts that animals which have evolved from a common ancestor would have similar genomes. House cats and wild African cats would have nearly identical genomes, lions and house cats would have more genomes in common than lions and dogs, who would have more in common than lions and alligators, who would have more in common than lions and worms. Surprise, surprise, as sequencing of more and more species becomes available, every single genome fits exactly (or very nearly) where it was predicted per evolution. Despite claims of creationism, that "evolution is not falsifiable", if one single genome of a racoon, or snapping turtle, or orchid did not have genes similar to its evolutionary neighbor, then evolution would have been disproved.
A five-year project called ENCODE (ENCyclopedia of DNA Elements) that involved 80 teams of scientists from five countries published its first results in the magazine Nature in June 2007. The project examined 1% of the human genome in detail to explore how the four bases of DNA combine to work within the human body. Their research showed that genes themselves make up only a small fraction of the three billion letters constituting the human genome. Areas previously thought to be junk DNA that served no practical purpose were found to be active inside cells, and other areas are thought to be potentially beneficial if environmental factors offer different evolutionary pressures. Some were responsible for creating chemical messengers to carry information from the genome to the cells' biological machinery.
This offers scientists the opportunity to study the genetic bases of complex medical conditions. The researchers aim to streamline the process to enable them to examine the rest of the genome over the next four years.
- These are the four paired "bases" seen in DNA: guanine, thymine, adenine, and cytosine.