人教课标版高中英语选修8unit2reading.pptVIP

Unit2 cloning is one that occurs  in a natural form of cloning  without human help. is one that is produced through human intervention(介入) .Warming upTwo kinds of clones:Natural cloneMan-made clone In pairs, look at these pictures and discuss which ones are natural clones and which ones are man-made. Explain how they differ.discussion A strawberry plantThe new plants that grow from the runners are exact copies of the original plant.Natural clone 一株草莓依靠它沿地“爬走”的匍匐茎,一年内就能长出数百株草莓苗A strawberry plantThe plant produces its own runners. Growing new plantsMan-made cloneA stem Take cuttings from growing plants to make new ones. 富贵竹插枝即活 The gardener cuts the plant ,and then the cutting produces another new plant.Man-made clone 富贵竹插枝即活仙人掌每块落地就生根 TwinsThey are born naturally and identical in sex and appearance.Natural clone Dolly是世界上第一例用体细胞─乳腺上皮细胞,通过细胞核移植技术,在复杂的人工操作下,得到的一只小绵羊 。 She was cloned while the others were born naturally.Dolly was a ______ sheep.clonedHow does Dolly differ from other sheep?Man-made cloneIn 1996, a sheep called Dolly was born. It is the first mammal to be cloned. It is considered to be the greatest success in the development of cloning. The following are some photos about cloning. See how much you know about it. 2001 cloning cattle2003 Cloning horsecloning rabbits2002 cloning cats 2005 cloning dogs克隆的荧光小猪(左)和正常小猪(右) In pairs discuss what you understand about cloning. Then list the questions you want to find out. Share your lists with one another.Pre-reading Questions about cloning1. What is a clone?A clone is group of cells or organisms that are genetically identical and have been produced asexually (无性生殖 /繁殖) from the same original cell. They include natural and man-made clones. Clone, also called reproduce asexually (无性生殖 /繁殖), is the creation of cells or whole animals using DNA from a single “parent”, without using the normal reproductive (有性生殖) pr