新研究推翻“原始汤”作为生命起源的理论
文章来源:未知 文章作者:meng 发布时间:2010-02-03 01:38 字体: [ ]  进入论坛
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For 80 years it has been accepted that early life began in a 'primordial1 soup原生汤,原始汤' of organic molecules2 before evolving out of the oceans millions of years later. Today the 'soup' theory has been over turned in a pioneering paper in BioEssays which claims it was the Earth's chemical energy, from hydrothermal vents深海热泉 on the ocean floor, which kick-started early life. "Textbooks have it that life arose from organic soup and that the first cells grew by fermenting使发酵,使动乱 these organics to generate energy in the form of ATP三磷酸腺苷. We provide a new perspective on why that old and familiar view won't work at all," said team leader Dr Nick lane from University College London. "We present the alternative that life arose from gases (H2, CO2, N2, and H2S) and that the energy for first life came from harnessing geochemical地球化学的 gradients渐变,梯度 created by mother Earth at a special kind of deep-sea hydrothermal vent3 – one that is riddled6 with tiny interconnected compartments7隔间,分隔 or pores气孔,毛穴."

The soup theory was proposed in 1929 when J.B.S Haldane published his influential8 essay on the origin of life in which he argued that UV radiation紫外线 provided the energy to convert methane9甲烷,沼气, ammonia氨 and water into the first organic compounds in the oceans of the early earth. However critics of the soup theory point out that there is no sustained driving force to make anything react; and without an energy source, life as we know it can't exist.

"Despite bioenergetic生物热量学 and thermodynamic热力学的 failings the 80-year-old concept of primordial soup remains10 central to mainstream11 thinking on the origin of life," said senior author, William Martin, an evolutionary12 biologist from the Insitute of Botany III in Düsseldorf. "But soup has no capacity for producing the energy vital for life."

In rejecting the soup theory the team turned to the Earth's chemistry to identify the energy source which could power the first primitive原始的,远古的 predecessors前任 of living organisms: geochemical gradients across a honeycomb of microscopic微观的 natural caverns16洞穴 at hydrothermal vents4. These catalytic起催化作用的 cells generated lipids脂肪,油脂, proteins and nucleotides核苷酸 giving rise to the first true cells.

The team focused on ideas pioneered by geochemist Michael J. Russell, on alkaline碱性的 deep sea vents, which produce chemical gradients very similar to those used by almost all living organisms today - a gradient of protons over a membrane17. Early organisms likely exploited these gradients through a process called chemiosmosis, in which the proton gradient is used to drive synthesis of the universal energy currency, ATP, or simpler equivalents. Later on cells evolved to generate their own proton gradient by way of electron transfer from a donor18 to an acceptor. The team argue that the first donor was hydrogen and the first acceptor was CO2.

"Modern living cells have inherited the same size of proton gradient, and, crucially, the same orientation19 – positive outside and negative inside – as the inorganic20 vesicles from which they arose" said co-author John Allen, a biochemist at Queen Mary, University of London.

"Thermodynamic constraints限制,约束 mean that chemiosmosis is strictly22 necessary for carbon and energy metabolism能量代谢 in all organisms that grow from simple chemical ingredients [autotrophy] today, and presumably the first free-living cells," said Lane. "Here we consider how the earliest cells might have harnessed a geochemically created force and then learned to make their own."

This was a vital transition, as chemiosmosis is the only mechanism24 by which organisms could escape from the vents. "The reason that all organisms are chemiosmotic today is simply that they inherited it from the very time and place that the first cells evolved – and they could not have evolved without it," said Martin.

"Far from being too complex to have powered early life, it is nearly impossible to see how life could have begun without chemiosmosis化学渗透", concluded Lane. "It is time to cast off the shackles手铐,脚镣 of fermentation发酵 in some primordial soup as 'life without oxygen' – an idea that dates back to a time before anybody in biology had any understanding of how ATP is made."



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1 primordial 11PzK     
adj.原始的;最初的
参考例句:
  • It is the primordial force that propels us forward.它是推动我们前进的原始动力。
  • The Neanderthal Man is one of our primordial ancestors.的尼安德特人是我们的原始祖先之一.
2 molecules 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。
3 vent yiPwE     
n.通风口,排放口;开衩;vt.表达,发泄
参考例句:
  • He gave vent to his anger by swearing loudly.他高声咒骂以发泄他的愤怒。
  • When the vent became plugged,the engine would stop.当通风口被堵塞时,发动机就会停转。
4 vents 3fd48768f3da3e458d6b73926735d618     
(气体、液体等进出的)孔、口( vent的名词复数 ); (鸟、鱼、爬行动物或小哺乳动物的)肛门; 大衣等的)衩口; 开衩
参考例句:
  • He always vents his anger on the dog. 他总是拿狗出气。
  • The Dandelion Patch is the least developed of the four active vents. “蒲公英区”在这四个活裂口中是发育最差的一个。
5 fermenting fdd52e85d75b46898edb910a097ddbf6     
v.(使)发酵( ferment的现在分词 );(使)激动;骚动;骚扰
参考例句:
  • The fermenting wine has bubbled up and over the top. 发酵的葡萄酒已经冒泡,溢了出来。 来自辞典例句
  • It must be processed through methods like boiling, grinding or fermenting. 它必须通过煮沸、研磨、或者发酵等方法加工。 来自互联网
6 riddled f3814f0c535c32684c8d1f1e36ca329a     
adj.布满的;充斥的;泛滥的v.解谜,出谜题(riddle的过去分词形式)
参考例句:
  • The beams are riddled with woodworm. 这些木梁被蛀虫蛀得都是洞。
  • The bodies of the hostages were found riddled with bullets. 在人质的尸体上发现了很多弹孔。 来自《简明英汉词典》
7 compartments 4e9d78104c402c263f5154f3360372c7     
n.间隔( compartment的名词复数 );(列车车厢的)隔间;(家具或设备等的)分隔间;隔层
参考例句:
  • Your pencil box has several compartments. 你的铅笔盒有好几个格。 来自《简明英汉词典》
  • The first-class compartments are in front. 头等车室在前头。 来自《简明英汉词典》
8 influential l7oxK     
adj.有影响的,有权势的
参考例句:
  • He always tries to get in with the most influential people.他总是试图巴结最有影响的人物。
  • He is a very influential man in the government.他在政府中是个很有影响的人物。
9 methane 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 remains 1kMzTy     
n.剩余物,残留物;遗体,遗迹
参考例句:
  • He ate the remains of food hungrily.他狼吞虎咽地吃剩余的食物。
  • The remains of the meal were fed to the dog.残羹剩饭喂狗了。
11 mainstream AoCzh9     
n.(思想或行为的)主流;adj.主流的
参考例句:
  • Their views lie outside the mainstream of current medical opinion.他们的观点不属于当今医学界观点的主流。
  • Polls are still largely reflects the mainstream sentiment.民调还在很大程度上反映了社会主流情绪。
12 evolutionary Ctqz7m     
adj.进化的;演化的,演变的;[生]进化论的
参考例句:
  • Life has its own evolutionary process.生命有其自身的进化过程。
  • These are fascinating questions to be resolved by the evolutionary studies of plants.这些十分吸引人的问题将在研究植物进化过程中得以解决。
13 primitive vSwz0     
adj.原始的;简单的;n.原(始)人,原始事物
参考例句:
  • It is a primitive instinct to flee a place of danger.逃离危险的地方是一种原始本能。
  • His book describes the march of the civilization of a primitive society.他的著作描述了一个原始社会的开化过程。
14 predecessors b59b392832b9ce6825062c39c88d5147     
n.前任( predecessor的名词复数 );前辈;(被取代的)原有事物;前身
参考例句:
  • The new government set about dismantling their predecessors' legislation. 新政府正着手废除其前任所制定的法律。 来自《简明英汉词典》
  • Will new plan be any more acceptable than its predecessors? 新计划比原先的计划更能令人满意吗? 来自《简明英汉词典》
15 microscopic nDrxq     
adj.微小的,细微的,极小的,显微的
参考例句:
  • It's impossible to read his microscopic handwriting.不可能看清他那极小的书写字迹。
  • A plant's lungs are the microscopic pores in its leaves.植物的肺就是其叶片上微细的气孔。
16 caverns bb7d69794ba96943881f7baad3003450     
大山洞,大洞穴( cavern的名词复数 )
参考例句:
  • Within were dark caverns; what was inside them, no one could see. 里面是一个黑洞,这里面有什么东西,谁也望不见。 来自汉英文学 - 家(1-26) - 家(1-26)
  • UNDERGROUND Under water grottos, caverns Filled with apes That eat figs. 在水帘洞里,挤满了猿争吃无花果。
17 membrane H7ez8     
n.薄膜,膜皮,羊皮纸
参考例句:
  • A vibrating membrane in the ear helps to convey sounds to the brain.耳膜的振动帮助声音传送到大脑。
  • A plastic membrane serves as selective diffusion barrier.一层塑料薄膜起着选择性渗透屏障的作用。
18 donor dstxI     
n.捐献者;赠送人;(组织、器官等的)供体
参考例句:
  • In these cases,the recipient usually takes care of the donor afterwards.在这类情况下,接受捐献者以后通常会照顾捐赠者。
  • The Doctor transplanted the donor's heart to Mike's chest cavity.医生将捐赠者的心脏移植进麦克的胸腔。
19 orientation IJ4xo     
n.方向,目标;熟悉,适应,情况介绍
参考例句:
  • Children need some orientation when they go to school.小孩子上学时需要适应。
  • The traveller found his orientation with the aid of a good map.旅行者借助一幅好地图得知自己的方向。
20 inorganic P6Sxn     
adj.无生物的;无机的
参考例句:
  • The fundamentals of inorganic chemistry are very important.无机化学的基础很重要。
  • This chemical plant recently bought a large quantity of inorganic salt.这家化工厂又买进了大量的无机盐。
21 constraints d178923285d63e9968956a0a4758267e     
强制( constraint的名词复数 ); 限制; 约束
参考例句:
  • Data and constraints can easily be changed to test theories. 信息库中的数据和限制条件可以轻易地改变以检验假设。 来自英汉非文学 - 科学史
  • What are the constraints that each of these imply for any design? 这每种产品的要求和约束对于设计意味着什么? 来自About Face 3交互设计精髓
22 strictly GtNwe     
adv.严厉地,严格地;严密地
参考例句:
  • His doctor is dieting him strictly.他的医生严格规定他的饮食。
  • The guests were seated strictly in order of precedence.客人严格按照地位高低就座。
23 metabolism 171zC     
n.新陈代谢
参考例句:
  • After years of dieting,Carol's metabolism was completely out of whack.经过数年的节食,卡罗尔的新陈代谢完全紊乱了。
  • All living matter undergoes a process of metabolism.生物都有新陈代谢。
24 mechanism zCWxr     
n.机械装置;机构,结构
参考例句:
  • The bones and muscles are parts of the mechanism of the body.骨骼和肌肉是人体的组成部件。
  • The mechanism of the machine is very complicated.这台机器的结构是非常复杂的。
25 shackles 91740de5ccb43237ed452a2a2676e023     
手铐( shackle的名词复数 ); 脚镣; 束缚; 羁绊
参考例句:
  • a country struggling to free itself from the shackles of colonialism 为摆脱殖民主义的枷锁而斗争的国家
  • The cars of the train are coupled together by shackles. 火车的车厢是用钩链连接起来的。
TAG标签: life soup primordial
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