What has cloning bypassed?

admin2010-06-30  40

问题 What has cloning bypassed?
  
What is cloning? Cloning is the creation of cells or whole animals using DNA from a single "parent", by passing the normal reproductive process. The clone has the same DNA as the parent.
     The most common process takes DNA from one cell and puts it in a hollowed-out egg. Chemicals and electricity are then used to encourage the new DNA to fuse with the egg and develop into an embryo. This technique is called nuclear transfer.
     The first cloned animal in human history is a sheep called Doily. It is very important because it was the first mammal to be cloned using DNA taken from an adult cell. Previously, animals had only been cloned using embryo cells, which already have the potential to become a complete embryo in its own right. The big breakthrough with Doily was to make a clone from an ordinary, adult cell.
     When it comes to the question of whether cloned animals are normal and healthy, the answer is YES. Dolly is, but scientists do not yet know whether this is the exception or the rule. Some early evidence suggests that clones may have health problems and that they may age prematurely.
     With the birth of Dolly; many people are worried that a human clone may be born soon. It’s possible in theory. But the technology of reproductive cloning is still in its very early stages and there is much that scientist do not understand. That’s more, human cloning is already banned by law in the United Kingdom. The former President of the United States Bill Clinton proposed banning research into producing human clones in the US for five years. Some measures have also been taken to establish international agreements banning live human clones.

选项 A、The United States
B、The United Kingdom
C、Switzerland
D、Russia

答案B

解析 信息题,文中提到两个国家,the United Kingdom和the United States,只有英国以法律形式正式禁止克隆人,所以选B。
转载请注明原文地址:https://kaotiyun.com/show/qsJd777K
0

随机试题
最新回复(0)