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.
The history of Earth is divided into four great eons, starting 4,540 mya with the formation of the planet. Each eon saw the most significant changes in Earth's composition, climate and life.