Section outline

  • General

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  • 变异原因

    What will you learn
    ::你会学到什么

    • What are the causes of
      ::造成以下原因的原因为何:
    • Types of spontaneous mutations
      ::自发突变类型

    Chernobyl disaster site with a memorial monument and power plant in the background.

    What does radiation contamination do?
    ::辐射污染有什么作用?

    It mutates . The Chernobyl disaster was a nuclear accident that occurred on April 26, 1986. It is considered the worst nuclear power plant accident in history. A Russian publication concludes that 985,000 excess cancers occurred between 1986 and 2004 as a result of radioactive contamination. The 2011 report of the European Committee on Radiation Risk calculates a total of 1.4 million excess cancers occurred as a result of this contamination.
    ::切尔诺贝利灾难是1986年4月26日发生的一次核事故,被认为是历史上最严重的核电厂事故。一份俄罗斯出版物得出结论,1986年至2004年期间,由于放射性污染,出现了985,000例超重癌症。欧洲辐射风险委员会2011年报告估计,由于这种污染,共发生140万例超重癌症。

    Causes of Mutation
    ::变异原因

    Mutations have many possible causes. Some mutations seem to happen spontaneously without any outside influence. They can occur when mistakes are made during DNA replication or . Other mutations are caused by environmental factors. Anything in the environment that can cause a mutation is known as a mutagen . Examples of mutagens are pictured in the  Figure . 
    ::变异有许多可能的原因。有些变异似乎自发发生,没有任何外部影响。当DNA复制过程中出现错误或出现错误时,这些变异就会发生。其他变异是由环境因素造成的。环境中任何可能导致变异的事物都被称为变异。图中显示了突变的例子。

    Examples of mutagens: radiation, chemicals, and infectious agents with respective illustrations.
    Examples of Mutagens. Types of mutagens include radiation, chemicals, and infectious agents. Do you know of other examples of each type of mutagen shown here?

    Spontaneous Mutations
    ::自发变异

    There are five common types of spontaneous mutations. These are described in the Table .
    ::有五种常见的自发突变类型,如表1所示。

    Mutation Description
    Tautomerism a base is changed by the repositioning of a hydrogen atom
    Depurination loss of a purine base (A or G)
    Deamination spontaneous deamination of 5-methycytosine
    Transition a purine to purine (A to G, G to A), or a pyrimidine to pyrimidine (C to T, T to C) change
    Transversion a purine becomes a pyrimidine, or vice versa

    The Chernobyl Disaster: Follow-up
    ::切尔诺贝利灾难:后续行动

    Though the area immediately around the Chernobyl disaster may not be safe for human life for thousands of years, the "Exclusion Zone" around the Chernobyl nuclear power station has become a haven for wildlife. As humans were evacuated from the area after the disaster , existing multiplied and rare not seen for centuries have returned or have been reintroduced, including the lynx, wild boar, wolf, Eurasian brown bear, European bison, Przewalski's horse, and eagle owl. The Exclusion Zone is so lush with wildlife and greenery that in 2007 the Ukrainian government designated it a wildlife sanctuary. It is now one of the largest wildlife sanctuaries in Europe.  
    ::尽管切尔诺贝利灾难附近地区可能数千年来对人的生命不安全,但切尔诺贝利核电站周围的“隔离区”已成为野生生物的避风港。 灾难发生后,人类从该地区撤离,已有数以百计的成倍和稀有的返回或被重新引入,包括林克斯、野猪、狼、欧亚棕熊、欧洲野牛、普泽瓦尔斯基的马和鹰鹰。 排外区充满野生生物和绿化,2007年乌克兰政府将其指定为野生生物保护区。 它现在是欧洲最大的野生生物保护区之一。

     

     

     

     

     

    Summary
    ::摘要

    • Mutations are caused by environmental factors known as mutagens.
      ::变异是由称为变异的环境因素造成的。
    • Types of mutagens include radiation, chemicals, and infectious agents.
      ::诱变性类型包括辐射、化学品和传染性制剂。
    • Mutations may be spontaneous in nature.
      ::变异可能是自发性质的。

    Review
    ::回顾

    1. Define mutation and mutagen.
      ::定义突变和诱变
    2. List three examples of mutagens.
      ::列举三个诱变性的例子。
    3. Distinguish between a transition and a transversion.
      ::区分过渡和转换。