Unit 2 Cloning Section Ⅰ Warming Up &；Reading-Pre-reading Have you ever wished you could have a clone of yourself to do your homework while you went out to play with your friends? Imagine if you could really do that, where would you start?What exactly is cloning?Cloning is a way of making an organism (有机体) that is an exact genetic (基因的) copy of another. This means that every single bit of DNA is the same between the two!You might not believe it, but there are human clones among us right now. They weren't made in a lab, though. They're identical (同样的) twins, created naturally. Below, we'll see how natural identical twins relate to modern cloning technologies.How is cloning done?You may have first heard of cloning when Dolly the sheep showed up on the scene in 1997. Cloning technologies have been around for much longer than Dolly, though. How does one go about making an exact genetic copy of an organism? There are a couple of ways to do this：artificial embryo twinning (人工胚胎双生) and somatic cell nuclear transfer (体细胞核移植). How do these processes differ?1．Artificial Embryo TwinningArtificial embryo twinning is the relatively lowtech version of cloning. As the name suggests, this technology mimics the natural process of creating identical twins.2．Somatic Cell Nuclear TransferSomatic cell nuclear transfer (SCNT), uses an approach different from artificial embryo twinning, but it produces the same result: an exact clone，or a genetic copy, of another. This was the method used to create Dolly the sheep.Section_ⅠWarming Up & Reading — Prereading[原文呈现][读文清障]CLONING：WHERE IS IT LEADING US?Cloning has always been with us and is here to stay. It is a way of making an exac...
