GNN Home. Genome sequencing is figuring out the order of DNA nucleotides, or bases, in a genomethe order of As, Cs, Gs, and Ts that make up an organism's DNA.The human genome is made up of over 3 billion of these genetic letters.hen you read a sentence, the meaning is not just in the sequence of the letters. It is also in the words those letters make and in the grammar of the language. Similarly, the human genome is more than just its sequence.
This blog entry thus provides a basic overview of the four Geologic Eras. The Precambrian Era (4.6 billion years ago to 600 million years ago) encompasses the great majority of Earth's geologic history, stretching from the formation of our planet to the appearance of shelled marine life.
Global paleogeographic reconstruction of the Earth in the late Cretaceous period 90 million years ago. (Courtesy Dr. Ron Blakey). The Mesozoic Era is the age of the dinosaurs and lasted almost 180 million years from approximately 250 to 65 million years ago. This era includes 3 well known periods called the Triassic, Jurassic, and Cretaceous periods. A mass-extinction marked the beginning and end of the Mesozoic Era. The event that caused the transition from the Paleozoic era to the Mesozoic era was the greatest extinction this earth has seen. This extinction wiped out about 95% of all marine life and 70% of land-life.