地球生命起源于彗星发现新证据-凯发k8官网

地球生命起源于彗星发现新证据
文章来源:未知 文章作者:enread 发布时间:2013-03-08 07:33 字体: [ ] 
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it's among the most ancient of questions: what are the origins of life on earth? a new experiment simulating conditions in deep space reveals that the complex building blocks of life could have been created on icy interplanetary dust and then carried to earth, jump-starting life.
 
chemists from the university of california, berkeley, and the university of hawaii, manoa, showed that conditions in space are capable of creating complex dipeptides(缩二氨酸) -- linked pairs of amino acids -- that are essential building blocks shared by all living things. the discovery opens the door to the possibility that these 1 were brought to earth aboard a comet or possibly 2(陨石), 3 the formation of proteins (polypeptides), 4 and even more complex molecules, such as sugars, that are necessary for life.
 
"it is fascinating to consider that the most basic biochemical building blocks that led to life on earth may well have had an extraterrestrial origin," said uc berkeley chemist richard mathies, coauthor of a paper published online last week and scheduled for the march 10 print issue of the astrophysical journal.
 
while scientists have discovered basic organic molecules, such as amino acids, in numerous meteorites that have fallen to earth, they have been unable to find the more complex 5 structures that are 6 for our planet's biology. as a result, scientists have always assumed that the really complicated chemistry of life must have originated in earth's early oceans.
 
in an ultra-high vacuum 7 chilled to 10 degrees above absolute zero (10 kelvin), seol kim and ralf kaiser of the hawaiian team simulated an icy snowball in space including carbon dioxide, ammonia(氨) and various 8(羟类) such as 9, ethane(乙烷) and propane(丙烷). when zapped with high-energy electrons to simulate the cosmic rays in space, the chemicals reacted to form complex, organic compounds, specifically dipeptides, essential to life.
 
at uc berkeley, mathies and amanda stockton then 10 the organic 11 through the mars organic analyzer, an instrument that mathies designed for ultrasensitive detection and identification of small organic molecules in the solar system. the analysis revealed the presence of complex molecules -- nine different amino acids and at least two dipeptides -- capable of catalyzing biological evolution on earth.
 
the research was supported by the national science foundation and the mathies 12 fund at uc berkeley.


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1 187c25e49d45ad10b2f266c1fa7a8d49     
分子( molecule的名词复数 )
参考例句:
  • the structure of molecules can be seen under an electron microscope. 分子的结构可在电子显微镜下观察到。
  • inside the reactor the large molecules are cracked into smaller molecules. 在反应堆里,大分子裂变为小分子。
2 12efd1ed528a28fe1f7cb667a7fbc1e0     
n.陨星( meteorite的名词复数 )
参考例句:
  • small meteorites have left impact craters all over the planet's surface. 这个行星的表面布满了小块陨石留下的撞击坑。 来自《简明英汉词典》
  • one theory about the existence of extraterrestrial life rests on the presence of carbon compounds in meteorites. 地球外存在生命的理论是基于陨星上存在碳化合物质这一事实的。 来自《简明英汉词典》
3 a6fd03b13b8e4974b4ae5f2576b96cb9     
v.催化,促进( catalyze的现在分词 )
参考例句:
  • enzymes catalyzing this reaction have been detected in plant extracts. 并在植物提取液中已经测出催化这个反应的酶系统。 来自辞典例句
  • transitional metals (fe3 ) play an extremely important role in catalyzing cla oxidation. 变价金属离子(fe~(3 ))能够促进共轭亚油酸氧化。 来自互联网
4 7881ad8ce9c83424f7874e70266ed2d8     
n. 酶,酵素
参考例句:
  • it was said that washing powders containing enzymes remove stains more efficiently. 据说加酶洗衣粉除污更有效。
  • among the enzymes which are particularly effective are pepsin, papain. 在酶当中特别有效的是胃朊酶、木瓜酶。
5 me9xh     
adj.分子的;克分子的
参考例句:
  • the research will provide direct insight into molecular mechanisms.这项研究将使人能够直接地了解分子的机理。
  • for the pressure to become zero, molecular bombardment must cease.当压强趋近于零时,分子的碰撞就停止了。
6 b5b8e67d6a37d24ad73c89e4c7ac8c9e     
先决条件,前提( prerequisite的名词复数 )
参考例句:
  • good muscles are one of the prerequisites of physical fitness. 肌肉发达是身体健康的一个必备条件。
  • one of the outstanding prerequisites of any city is a local transportation system. 本地运输系统是任何城市的突出前提条件之一。
7 wnky9     
n.房间,寝室;会议厅;议院;会所
参考例句:
  • for many,the dentist's surgery remains a torture chamber.对许多人来说,牙医的治疗室一直是间受刑室。
  • the chamber was ablaze with light.会议厅里灯火辉煌。
8 e809b45a335ac8bfbaa26f5ce65d98e9     
n.碳氢化合物,烃( hydrocarbon的名词复数 )
参考例句:
  • hydrocarbons (hc), like carbon monoxide, represent unburned and wasted fuel. 碳氢化合物(hc)像一氧化碳一样,为未燃尽的和被浪费掉的燃料。 来自英汉非文学 - 环境法 - 环境法
  • with this restricted frequency range it is not applicable to hydrocarbons. 这个较紧缩的频率范围不适用于烃类。 来自辞典例句
9 t1eyx     
n.甲烷,沼气
参考例句:
  • the blast was caused by pockets of methane gas that ignited.爆炸是由数袋甲烷气体着火引起的。
  • methane may have extraterrestrial significance.甲烷具有星际意义。
10 483f1acae53789fbee273a644fdcda80     
v.分析( analyze的过去式和过去分词 );分解;解释;对…进行心理分析
参考例句:
  • the doctors analyzed the blood sample for anemia. 医生们分析了贫血的血样。 来自《简明英汉词典》
  • the young man did not analyze the process of his captivation and enrapturement, for love to him was a mystery and could not be analyzed. 这年轻人没有分析自己蛊惑著迷的过程,因为对他来说,爱是个不可分析的迷。 来自《简明英汉词典》
11 3e5a3e323766c2626c2be0d6feafa1da     
n.剩余,余渣( residue的名词复数 );剩余财产;剩数
参考例句:
  • pesticide residues in fruit and vegetables 残留在水果和蔬菜中的杀虫剂
  • all organic and metallic residues on the wafers must be removed. 片子上所有的有机和金属残留物均必须清除。 来自辞典例句
12 ix6xn     
n.皇家,皇族
参考例句:
  • she claims to be descended from royalty.她声称她是皇室后裔。
  • i waited on tables,and even catered to royalty at the royal albert hall.我做过服务生, 甚至在皇家阿伯特大厅侍奉过皇室的人。
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