Is extinction really forever?

People are fascinated with extinct organisms. How exciting would it be to see a trilobite on the ocean bed, or observe a Tyrannosaurus rex? Past books and films about this fantasy involved time travel, but more recent stories use ancient DNA to clone and resurrect extinct organisms. It is a marvellous example of art imitating and leading science. The past 50 years have seen the discovery of the structure of DNA and the development of techniques for manipulating DNA, spawning the biotechnology industry. We now have genetically modified foods, Dolly the cloned sheep (now deceased) and other cloned animals. We have also extracted ancient DNA from fossils such as insects embedded in amber and even the leg bone of a Tyrannosaurus rex. A natural progression of the imagination is to use ancient DNA to re-create extinct organisms. Recently the Australian Museum attempted unsuccessfully to clone the extinct thylacine (Tasmanian tiger) (Plate 5.1) using DNA from a preserved specimen, but they were able to show that parts of some genes could function when inserted into mouse cells.

Chapter aims

In this chapter, we examine the molecular processes of cells, giving you the background to understand these techniques and to evaluate their environmental significance. We examine the hereditary material and how it codes messages, controls cells and is copied and distributed over generations through cell division; and we apply this knowledge to conservation.