生物專業(yè)英語(yǔ)第六章生命的起源課件

1、Unit 6 The origin and diversity of lifeRomeoBackgroundWords and phrasesText AnalysisContentsHome to millions of species, including humansNow, Earth is the only place in the universe where life is known to exist.The earth is Full of charmSuch Colorful life on the earth-?A question also immediately we

2、 faced-Where does life on earth come from -where is the origin of life應(yīng)當(dāng)追溯到與生命有關(guān)的元素及化學(xué)分子的起源- 這個(gè)過程應(yīng)當(dāng)從宇宙形成之初、通過所謂的“大爆炸”Big Bang產(chǎn)生了碳、氫、氧、氮、磷、硫等構(gòu)成生命的主要元素談起。生命的起源與演化VS宇宙的起源與演化密切相關(guān)-構(gòu)成生命元素如碳、氫、氧、氮、磷、硫等是來自“大爆炸”后元素的演化。資料表明前生物階段的化學(xué)演化并不局限于地球，在宇宙空間中廣泛地存在著化學(xué)演化的產(chǎn)物。在星際演化中，某些生物單分子，如氨基酸、嘌呤、嘧啶等可能形成于星際塵?；蚰鄣男窃浦?，接著在行星表

3、面的一定條件下產(chǎn)生了像多肽、多聚核苷酸等生物高分子。通過若干前生物演化的過渡形式最終在地球上形成了最原始的生物系統(tǒng)，即具有原始細(xì)胞結(jié)構(gòu)的生命。至此，生物學(xué)的演化開始，直到今天地球上產(chǎn)生了無(wú)數(shù)復(fù)雜的生命形式。生命的起源起源的時(shí)間科學(xué)回答生命起源的時(shí)間- 化石迄今為止，我們發(fā)現(xiàn)了最古老的生物化石是來自澳大利亞西部，距今約三十五億年前的巖石，這些化石類似于現(xiàn)在的藍(lán)藻，它們是一些原始的生命，是肉眼看不見的。它的大小只有幾個(gè)微米，到幾十個(gè)微米。同時(shí)我們知道地球的形成年齡大約在46億年前，這兩個(gè)數(shù)據(jù)我們就可以看到生命起源的年齡，大致可以界定在46億年到35億年之間。生命起源的幾種假說創(chuàng)世說-圣經(jīng)上說，起初

4、，神創(chuàng)造天地。自生論-生命是從無(wú)生命物質(zhì)自然發(fā)生的。如希臘人認(rèn)為，昆蟲生于土壤，春天萬(wàn)象更新，種子從泥土里萌發(fā)，昆蟲從去年留下的卵殼中破殼而出。還有比如說埃及人認(rèn)為生命來自于尼羅河，在中國(guó)古代也有腐草生螢之說。宇宙生命論-提倡“一切生命來自宇宙”觀點(diǎn)，認(rèn)為地球上最初的生命來自宇宙間的其他星球，即“地上生命，天外飛來”。這一假說認(rèn)為，宇宙太空中的“生命胚種”可以隨著隕石或其他途徑跌落在地球表面，即成為最初的生命起點(diǎn)。化學(xué)起源說-地球上的生命是在地球溫度逐步下降以后，在極其漫長(zhǎng)的時(shí)間內(nèi)，由非生命物質(zhì)經(jīng)過極其復(fù)雜的化學(xué)過程，一步一步地演變而成的。標(biāo)志：1859年，達(dá)爾文物種起源-告訴我們今天地球上，

5、色彩繽紛，種類繁多的生命是經(jīng)過長(zhǎng)期的演化由過去稀少的物種逐漸發(fā)展而來的進(jìn)化論-為生物科學(xué)帶來前所未有的大變革，同時(shí)也為人類揭示生命起源千古之謎帶來了一絲曙光，這也就是現(xiàn)代的化學(xué)進(jìn)化論。生命起源的化學(xué)進(jìn)化論首先在1953年首先得到了一位美國(guó)的學(xué)者米勒的證實(shí)-米勒實(shí)驗(yàn) 宇宙大爆炸(Big Bang) 大約在150億年前，宇宙所有的物質(zhì)都高度密集在一點(diǎn)，有著極高的溫度，因而發(fā)生了巨大的爆炸。大爆炸以后，物質(zhì)開始向外大膨脹，就形成了今天我們看到的宇宙。在這150億年中先后誕生了星系團(tuán)、星系、我們的銀河系、恒星、太陽(yáng)系、行星、衛(wèi)星等。人類就是在這一宇宙演變中誕生的。 卡爾林奈4. kingdom kid

6、m n. 界5. phylum n. 門(動(dòng)物） failm 7. class n. 綱6. division n. 門（植物）8. order n. 目9. family n. 科10. genus n. 屬11. species n. 物種，種 界-Animalia 動(dòng)物界 門 -Chordata 脊索動(dòng)物門 綱- Mammalia 哺乳綱 目- Carnivora 食肉目 科- Felidae 貓科 屬- Felis 貓 種-Felis domesticus家貓 12. coacervate kusveitn. 團(tuán)聚體，凝聚層A collection of organic macromo

7、lecules surrounded by water molecules that are aligned to form a sphere. 13. continental driftn. 大陸漂移 ,kntinentl drift The theory that the present continents result from the break-up of a larger continent and have moved independently to their present positions.大陸漂移學(xué)說是德國(guó)科學(xué)家阿爾弗雷德魏格納提出的一個(gè)假說，主要內(nèi)容為遠(yuǎn)古時(shí)代的地

8、球只有一塊“泛大陸”的龐大陸地，被稱為“泛海洋”的水域包圍，大約于2億年以前“泛大陸”開始破裂，在到距今約二三百萬(wàn)年以前，漂移的大陸形成現(xiàn)在的七大洲和四大洋的基本地貌。14. core k:n. 核心 The core of the Earth is that part lying below the mantle.n. 地幔，外套部16.mantle mntl The part of the interior of the Earth between the crust and the core.17. liposome n. 脂質(zhì)體 lipsm,lai- A vesicle formed

9、by the homogenization (emulsification) of phospholipids in dilute salt solutions. Liposomes are the prototypes of membrane-bound biologic structures.phospholipid：fsflipid 磷脂 生物學(xué)定義：當(dāng)兩性分子如磷脂和鞘脂分散于水相時(shí)，分子的疏水尾部?jī)A向于聚集在一起，避開水相，而親水頭部暴露在水相，形成具有雙分子層結(jié)構(gòu)的的封閉囊泡，稱為脂質(zhì)體。19. proteinoidn. 類蛋白 prutinid A proteinlike str

10、ucture of branched amino acid chains that is the basic structure of a microsphere.指氨基酸在干燥狀態(tài)下加熱聚合而成的類似蛋白質(zhì)的聚合物。20. taxonn. 分類單位，分類群 tksn 21. taxonomyn. 分類學(xué) tksnmi Words and Phrases:13. Liposome n. 脂質(zhì)體14. Mantle n. 地幔，外套部15. Order n. 目16. ozone layer n. 臭氧層17. Phylum n. 門18. Proteinoid n. 類蛋白19. Specie

11、s n. 物種，種20. Taxon n. 分類單位，分類群21. Taxonomy n. 分類學(xué)Text Analysis1.A Home for Life: Formation of the Solar System and Planet EarthThe story of lifes origins begins with the formation of the earth. The sequence of events that gave rise to our planet began, in turn, with the cosmic explosion physicists c

12、all the Big Bang. 生命起源于地球的形成。相對(duì)應(yīng)地，我們行星的形成源于一連串的事件，其始作俑者便是宇宙爆炸論物理學(xué)家所說的大爆炸。 The earth is composed of a number of layers: a solid crust, a semisolid mantle, and a largely molten (liquid) core that has a solid center. Basic physical features of Earth that may have made the emergence of life possible inc

13、lude the planets size, temperature, composition, and distance from the sun. 地球由多層組成：堅(jiān)硬的地殼、半固體的地幔、大且堅(jiān)實(shí)的熔融地核。地球的基本特征使生命的出現(xiàn)成為可能，這些特征包括行星的大小、溫度、組成以及與太陽(yáng)的距離。 The major current hypothesis holds that life arose spontaneously on the early earth by means of chemical evolution from nonliving substances.當(dāng)前主要的假說

14、認(rèn)為，在地球形成早期由非生命物質(zhì)的化學(xué)進(jìn)化自發(fā)產(chǎn)生了生命。hypothesis英 haipisisn.假設(shè)，假說；邏前提spontaneously 英 spntensl adv. 自然地，自發(fā)地，不由自主地； 不禁； 油然 2.The Emergence of life: Organic and Biological Molecules on a Primitive PlanetEvidence for prelife stages of chemical organization comes from laboratory experiments that try to duplicate

15、the physical environment and chemical resources of the early earth. 通過模擬地球早期的自然環(huán)境和化學(xué)條件，科學(xué)家在實(shí)驗(yàn)室中獲得了化學(xué)有機(jī)體生命前階段的證據(jù)。 These experiments, including the pioneering work of Miller and Urey, have successfully produced organic monomers including amino acids, simple sugars, and nucleic acid bases. 這些開創(chuàng)性的實(shí)驗(yàn)由米勒和

16、尤利完成，實(shí)驗(yàn)成功地獲取了有機(jī)單體，包括氨基酸、單糖、核酸堿基。1953年由美國(guó)芝加哥大學(xué)研究生米勒（S.L.Miller）在其導(dǎo)師尤利（H.C.Urey）指導(dǎo)下完成。米勒模擬實(shí)驗(yàn) 一種模擬在原始地球大氣中進(jìn)行雷鳴閃電能產(chǎn)生有機(jī)物（特別是氨基酸），以論證生命起源的化學(xué)進(jìn)化過程的實(shí)驗(yàn)。Experiments by Miller (Univ. of Chicago):BathusIn a reducing environment, amino acids and bases are easy to synthesize from naturally occurring molecules. The

17、 experiments fail in a neutral or oxygen-rich atmosphere.Chemical stagetovacuumpumpboiling watersparkdischargeliquid water in trapwater containingorganic compoundswater dropletswater incondenserelectrodeswater outCH4NH3H2OH2gases1953:Urey-Miller experiment1938:Aleksandr OparinBalthusBalthus The prob

18、able next step toward life was the spontaneous linking of such monomers into polymers such as proteinoids and nuclei acids. Current research suggests that likely sites for this polymerization were clay or rock surfaces.這些單體自發(fā)的連接成多聚體，如類蛋白和核酸，使進(jìn)入生命狀態(tài)成為可能。最近的研究表明這些聚合作用可能發(fā)生在泥土或巖石表面。 Researchers have fou

19、nd that, when energy is available to a system, they can generate three kinds of organic molecular aggregates. The Russian Aleksandr Oparin obtained polymer-rich droplets, called coacervates from solutions of polymers. 研究者們發(fā)現(xiàn)當(dāng)一個(gè)系統(tǒng)獲得能量時(shí)，可能產(chǎn)生3種有機(jī)分子的聚集體。俄國(guó)科學(xué)家Aleksandr Oparin從多聚物的溶液中得了富含多聚物的小液滴，即凝聚物；Alex

20、ander I. Oparin他認(rèn)為原始地球上無(wú)游離氧的還原性大氣在短波紫外線等能源作用下能生成簡(jiǎn)單有機(jī)物(生物小分子)，簡(jiǎn)單有機(jī)物可生成復(fù)雜有機(jī)物(生物大分子)并且在原始海洋中形成多分子體系的團(tuán)聚體，后者經(jīng)過長(zhǎng)期的演變和“自然選擇”，終于出現(xiàn)了原始生命即原生體。化學(xué)進(jìn)化論的實(shí)驗(yàn)證據(jù)越來越多己為絕大多數(shù)科學(xué)家所接受。Proteinoids coacervates compartmentalization proto-cells metabolism類蛋白-凝聚物-區(qū)分-細(xì)胞前體-代謝作用BalthusCoacervation = electrostatically-driven liquid-

21、liquid phase separation, resulting from association of oppositely charged macro-ions團(tuán)聚體=靜電驅(qū)動(dòng)的液-液相分離，由帶相反電荷的大離子產(chǎn)生關(guān)聯(lián) The term coacervate is sometimes used to refer to spherical aggregates of colloidal droplets held together by hydrophobic forces 團(tuán)聚體有時(shí)可以指由疏水力聚集在一起的膠體液滴的球型聚集體。Balthus Sidney Fox generate

22、d proteinoid microspheres from mixtures of amino acids and water. A third laboratory structure is the liposome, a spherical lipid bilayer that forms from phospholipids. A structure similar to one or more of these aggregates may have been the precursor of true cells.Sidney Fox從氨基酸和水的混合液獲得了類蛋白微球體；實(shí)驗(yàn)室得

23、到的第三種結(jié)構(gòu)物質(zhì)是脂質(zhì)體，即由磷脂形成的球形脂雙層結(jié)構(gòu)。這三種聚集體中的一種或多種結(jié)構(gòu)類似物可能是真細(xì)胞的前體。 Further steps in the appearance of cells on the earth included the development of RNA and DNA as biological information molecules. 關(guān)于地球上細(xì)胞出現(xiàn)的進(jìn)一步的研究包括RNA和DNA作為生物信息分子的研究進(jìn)展。Evidence suggests that RNA, which can form spontaneously under condition

24、s mimicking those of the early earth, was the first informational molecule. 有證據(jù)表明在實(shí)驗(yàn)室模擬早期地球自然條件下RNA可自發(fā)形成，這可能是地球早期形成的第一個(gè)貯藏信息的分子。 The discovery of RNA ribozymes-RNA that can act as an enzymelike catalyst suggests that such catalytic RNA also could have assembled new RNAs from early nucleotides. Certai

25、n catalytic RNAs can also carry out sexlike exchanges of pieces of RNA.核酶的發(fā)現(xiàn)說明RNA具有類似酶的活性，可以催化早期核酸形成新的RNA。對(duì)于RNA物種而言，某些催化RNA具備類似于性交換的功能。 Following the development of a lipid-protein surface layer and replicating RNA and DNA informational molecules, the events leading to the emergence of living cells

26、would have included the origin of the genetic code; the sequestering of RNA or DNA into cell-like structures; and the development of metabolic pathways.接下來脂蛋白表層的形成、RNA 和DNA信息分子的復(fù)制，最終導(dǎo)致活細(xì)胞的出現(xiàn)。包括最初的遺傳密碼，RNA或DNA被包裹進(jìn)細(xì)胞樣的結(jié)構(gòu)中，及代謝途徑的建立。3.The Earliest CellsThe oldest fossils that may represent living cells

27、are found in rocks that are about 3.5 billion years old. The cells were probably anaerobic heterotrophs, with autotrophs arising much later. 能說明活細(xì)胞存在的最古老的化石大約有35億年了。最早出現(xiàn)的細(xì)胞可能是厭氧異養(yǎng)生物，自養(yǎng)生物很久后才出現(xiàn)。anaerobic：n,eirubik 厭氧的The first autotrophs produced their own nutrients and released O2-a metabolic by-pro

28、duct that had a crucial impact on later life forms. The resulting ozone layer in the earths atmosphere reduced the penetration of ultraviolet light.最早的自養(yǎng)生物自己生產(chǎn)營(yíng)養(yǎng)物質(zhì)并釋放氧氣，這個(gè)新陳代謝副產(chǎn)物對(duì)后期生命的形成有一個(gè)深遠(yuǎn)的影響。地球上大氣中臭氧層的出現(xiàn)減少了紫外線的穿透力。 As a result, cells would survive in shallow water and on the land surface. The in

29、creasing quantity of atmospheric oxygen also permitted the evolution of aerobic cells and cellular respiration, which in turn signaled the beginning of the global carbon cycle. 結(jié)果，細(xì)胞就能夠在淺水區(qū)和陸地上生存了。大氣中氧氣含量的增加使得需氧細(xì)胞進(jìn)化并產(chǎn)生細(xì)胞呼吸，這標(biāo)志著全球碳循環(huán)的開始。Although the earliest cells were all prokaryotes, by about 1.5 b

30、illion years ago eukaryotes appeared.最早期的細(xì)胞都是原核細(xì)胞，直到大約15億年前，真核細(xì)胞才出現(xiàn)。prokaryote：,prukrit原核生物 4.The Changing Face of planet EarthChanges in land masses, the seas, and climate have greatly affected the evolution of life on the earth. The basic parts of the planet include a light, solid crust over a hot

31、, semisolid mantle and an inner, partially molten core. 大陸板快、海洋、氣候的改變對(duì)地球上生命的進(jìn)化有著巨大的影響。行星的基本組成包括輕且硬的地殼、熾熱的半固體地幔和局部熔融的地核。Massive segments or plates of the crust move over the mantle in the process of continental drift. Over the past 500 million years, continental drift has sculpted the earths crusts t

32、o produce the form and distribution of present-day continents. 地幔上大板塊地殼的擠壓形成大陸漂移。在過去的五億年大陸漂移塑造了地殼的外觀，使現(xiàn)在大陸的分散存在。Climatic changes that greatly affected living organisms accompanied these plate movements; the period was marked by occasional waves of mass extinctions of living creatures. 伴隨板塊運(yùn)動(dòng)，氣候改變對(duì)活有

33、機(jī)體有著巨大的影響。生物大規(guī)模滅絕高峰的偶然性事件的涌現(xiàn)是這個(gè)時(shí)期的標(biāo)志。Organisms were also affected by periods of glaciation that followed variations in the earths orbit and in the output of energy by the sun.生物也受冰河期影響，在冰河期，地球軌道和太陽(yáng)能的供應(yīng)都發(fā)生了很大變化。5.Taxonomy: Categorizing the Variety of living ThingsBiologists use the binomial system of nomenclature developed by Linnaeus to categorize the varieties of life on the earth. The system assigns each type of organism to a genus and species. 生物學(xué)家利用林奈發(fā)展的雙名法對(duì)多樣化的生物分類。雙名法把每種類型的生物按屬和種分開， Organisms are then further classified into higher ta