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  • 生物前化学

    Once biochemists understood some of the important chemistry in living organisms, a new field of synthetic biology was born. Biochemists tried to replicate the pathway for the evolution - or the complexification - of simple chemistry. 
    ::一旦生物化学家理解了生物体中一些重要的化学,就产生了一个新的合成生物学领域。 生物化学家试图复制简单化学进化(或复杂化)的路径。

    In 1953, Stanley Miller and Harold Urey published the results of  their now famous experiment: they spontaneously produced amino acids from simple elements under conditions emulating early Earth. Given the importance of amino acids and proteins  for life, this  experiment was  viewed as an important step toward understanding the origin of life. 
    ::1953年,斯坦利·米勒( Stanley Miller)和哈罗德·乌雷(Harold Urey)发表了他们现在著名的实验结果:他们自发地在早期地球模拟条件下从简单的元素中产生氨基酸。 考虑到氨基酸和蛋白质对生命的重要性,这一实验被视为了解生命起源的一个重要步骤。

     

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    The set up of the Miller-Urey experiment. Gases characteristic of the early Earth atmosphere (water, methane, ammonia, and hydrogen) filled one bulb and was subject to lightning while the other bulb was filled with water and heated to simulate the ocean and induce evaporation. What is the reasoning behind having two locations for sampling probes, one directly connected to the ocean and one in the u-bend trap?
    ::米勒-尤里实验的建立。 早期地球大气(水、甲烷、氨和氢)的气体特征(水、甲烷、氨和氢)装满了一个灯泡,并被闪电击中,而另一个灯泡则装满了水,并被加热以模拟海洋和引起蒸发。 有两个取样地点,一个与海洋直接相连,另一个在u-bend陷阱中,其理由是什么?

    The experimental setup,  depicted in the    above, consisted of two large flasks. One flask  contained gases thought to be present in the primitive atmosphere ( methane, ammonia, and hydrogen) and the other  contained   water, representing  the ocean. Electrodes were inserted into the atmosphere flask to produce electrical sparks that would emulate lightning.
    ::上面所描述的实验装置由两个大瓶组成:一个瓶装被认为存在于原始大气中的气体(甲烷、氨和氢),另一个瓶装水代表海洋;电极插入大气瓶,产生模拟闪电的电火花。

    The ocean flask was heated, producing water vapor that traveled throughout the setup and interacted with gases in the atmosphere and simulated lightning.  The enriched vapor then traveled through a condenser and cooled  to a liquid state in a u-bend at the bottom of the setup where samples could be collected. Within a day of running the experiment, the liquid at the bottom of this u-bend had turned pink. The inaugural run of the experiment lasted for a week. From these results, Miller was able to identify five different amino acids that had been created from this simple set up of atmospheric gases, lightning, and water alone. As expected, the chirality of these amino acids  included  both left- and right-handed molecules , even though only left-handed amino acids are incorporated into biology as we know it today. R ecent reanalysis of sealed vials have   detected   more than 20 different amino acids that were actually formed during that one- week experiment . 
    ::海水瓶被加热, 产生贯穿整个构造中的水蒸气, 与大气中的气体和模拟闪电互动。 浓缩蒸气经过一个冷凝器, 冷却到液态, 在结构的底部, 可以采集样本。 在进行实验的一天里, 这个乌盆底部的液体已经变成粉色。 实验的初始运行持续了一周。 从这些结果中, 米勒能够识别出五个不同的氨基酸, 它们是由这个简单的大气气体、 闪电和水组成的结构所创造出来的。 正如人们所预期的那样, 这些氨基酸的精密性包括左手和右手分子, 尽管我们今天知道只有左手的氨基酸被纳入生物学。 最近对密封的瓶子的重新分析发现超过20种不同的氨基酸, 它们是在为期一周的实验中实际形成的。

    Since 1953, there have been many  additional  experiments that aim to synthesize the building blocks of life. Longer chains of amino acids and polypeptides have been synthesized.  An impressive experiment was carried out by John Sutherland's lab in 2009. Sutherland began with a compound called 2-amino-oxazole, and using phosphorus as a catalyst, he was able to synthesize  some of the   nucleotides  used in RNA and DNA.
    ::自1953年以来,还进行了许多旨在合成生命构件的其他实验,合成了较长的氨基酸和聚苯醚链,约翰·萨瑟兰实验室于2009年进行了令人印象深刻的实验,萨瑟兰从一个名为2-氨基氧化氮的化合物开始,使用磷作为催化剂,他得以合成了RNA和DNA中使用的一些核糖核酸。

    The Murchison Meteorite - amino acids in space
    ::Murchison Meteorite - 空间的氨基酸

    On September 28, 1969, two months after Apollo 11 landed on the moon, a huge meteorite soared through the sky and landed near Murchison, Victoria, in Australia. The   Murchison Meteorite is one of the most valuable and well-studied meteorites.  Importantly, the incoming meteorite was highly visible.  It flew through the atmosphere as a fireball and caused a  noticeable tremor when it landed. This allowed for rapid recovery of the meteorite, preventing terrestrial contamination. A piece of the Murchison meteorite is shown .
    ::1969年9月28日,在阿波罗11号登陆月球两个月后,一颗巨大的陨石飞过天空,降落在澳大利亚维多利亚州穆奇森附近,穆奇森流星是价值最高、研究最深的陨石之一。重要的是,即将到来的陨石以火球形式在大气中飞过,在坠落时引起明显的震颤。这可以迅速恢复陨石,防止陆地污染。展示了一块穆奇森流星。

     

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    A segment of the Murchison Meteorite. The Murchison Meteorite is classified as a carbonaceous, or carbon-rich, chondrite, a particularly interesting class of meteorites due to the central role carbon plays in biology. Chondrules are round grains present in metoroids or asteroids that formed as round, molten droplets. Can you spot the round chondrules visible in this image of the meteorite?
    ::Murchison Meteorite 的一部分。 Murchison Meteorite 被归类为碳化或碳富, chondrite, 由于碳在生物学中的核心作用, 是一种特别有趣的陨石。 Chondrules 是机器人或小行星中的圆粒子, 它们是圆状的, 熔化的滴子。 你能看到在陨石的图像中可见的圆形和弦吗 ?

    In total, more than 100 kg ( the average weight of an NFL linebacker)  of the Murchison Meteorite was recovered over an area of 13 square kilometers. This meteorite contained  more than 70 amino acids, many of which are not known to exist on Earth. There is a slight over-abundance of left-handed amino acids, which suggests that there may be a cosmic origin to the dominance of  left-handed amino acids that are used by life on Earth. Every amino acid discovered on the Murchison Meteorite has since been successively synthesized using a Miller-Urey-like setup with gases, water, and simulated lightning, demonstrating that these amino acids  can spontaneously form under fairly simple conditions. The Murchison Meteorite  is proof that  amino acids can  easily form in space. Amino acids: so easy to synthesize that a rock  can do it!
    ::Murchison Meteorite 的100公斤以上(NFL线背心的平均重量) 的Murchison Meteorite 在一个13平方公里的区域中被回收。 该陨石含有70多枚氨基酸,其中许多在地球上并不存在。 左撇子氨基酸略为过剩, 这表明地球上生命使用的左撇子氨基酸的主导地位可能具有宇宙起源。 Murchison Meteorite 上发现的每颗氨基酸自此以类似Miller-Urey的气、 水和模拟闪电装置相继合成, 表明这些氨基酸可以在相当简单的条件下自发形成。 Murchison Meteorite 证明了氨基酸在太空中很容易形成。 氨基酸: 很容易合成, 岩石可以做到这一点 !

        Meteors and Meteoroids and Meteorites
    ::气象、流星体和流星体

    The root word,   meteor , comes from the Greek word for ''high in the air."
    ::根词,陨石,来自希腊语中的"高空"

    Meteoroids   are small rocky bodies in space. They are smaller in size  than  asteroids or icy comets. When a meteoroid enters the Earth's atmosphere, interactions with the gases in the atmosphere heat up  the outer layer, which  crumbles   away and creates a glowing trail. This light show is what is called a   meteor . More colloquially, they are identified as falling stars and are the stuff of Hollywood wishes.
    ::流星体是空间中的小岩石体,小于小行星或冰慧星。当流星体进入地球大气层时,与大气中的气体的相互作用会把大气层中的气体加热到外层,而外层会分崩离析并产生发光的踪迹。这个光显示就是所谓的流星。更概括地说,它们被确定为坠落的恒星,是好莱坞的愿望所在。

    On an average day, 4-8 meteors  can be seen every hour, but the number varies greatly by season and time of night. A   meteor shower   is a time of increased meteors,  generally caused  when the orbit of the Earth crosses a trail of debris left from passing comets. Since the Earth crosses this material regularly in its orbit, particular meteor showers occur at the same time every year. The Perseid meteor shower occurs in mid-August and the Leonid meteor shower can be seen in mid-November.
    ::平均每天4-8颗流星,每小时可以看到4-8颗流星,但数量因季节和夜间时间而变化很大。流星雨是流星不断增多的时期,通常由地球轨道穿越经过的彗星留下的碎片的足迹而引起。由于地球定期穿过这些物质,每年同时发生流星雨。佩尔赛德流星雨在8月中旬发生,列奥尼德流星雨在11月中旬可见。

    Meteorites   are meteoroids that have survived  atmospheric heating from the meteor phase and landed on Earth. Most meteors burn up in the atmosphere, so meteorites are relatively rare.   , has a sample of rocks that the  were initially believed to be meteorites, but  with a terrestrial origin, according to  the Department of Earth and Planetary Science at Washington University.
    ::根据华盛顿大学地球和行星科学系的资料,流星是从流星级到地球的大气热中幸存下来并降落在地球上的流星体,大多数流星在大气中燃烧,因此陨星相对罕见。 根据华盛顿大学地球和行星科学系的资料,这些流星体具有最初被认为是陨星的岩石样本,但具有陆地来源。

    Even more complex organic molecules have been detected in interstellar space, a testament to how easily complex, carbon-based structures can form and remain stable. Some of these molecules  have carbon  ring-structures called polycyclic aromatic hydrocarbons and are similar to the organic molecules found  in biological organisms.  This confirms  that carbon is a good base for forming complex molecules structures, including amino acids. While this gives a hint that carbon-based  life may  also exist   on other planets , there  are still  many  steps we don't yet understand about how to go from prebiotic chemistry to life.
    ::更复杂的有机分子在星际空间中被检测到,这证明了碳基结构能够形成并保持稳定。其中一些分子有碳环结构,称为多环芳烃,与生物生物生物中发现的有机分子相似。这证实碳是形成复杂分子结构的良好基础,包括氨基酸。这说明碳基生命可能存在于其他行星上,但我们还不知道如何从生物前化学走向生命。

    Nucleic Acids
    ::核酸

    RNA (ribonucleic acid)  and DNA (deoxyribonucleic acid)  are long-chain complex nucleic acids that  enable  the transfer of information through a genetic code  during cell replication . Gene replication and specifically the errors that occur during gene replication  allow organisms to be altered so that specific  traits that are better adapted to the environment  can be selected. Thanks to genetic mutations and natural selection, giraffes have  evolved  to reach the leaves of tall trees  on our planet.
    ::RNA(核糖核酸)和DNA(脱氧核糖核酸)是长链复合核酸,能够在细胞复制期间通过基因编码传递信息。基因复制,特别是基因复制过程中出现的错误,可以改变生物体,从而选择更适合环境的具体特征。通过基因突变和自然选择,长颈鹿演变到我们星球上的高树叶。

     

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    RNA and DNA consist of nucleotides with three components: a sugar, a phosphate group, and a base. What differences do you see between RNA and DNA?
    ::RNA 和 DNA 由 核糖、 磷酸盐 组和基 基组成 。 你看到 RNA 和 DNA 之间有什么区别 ?

     

    N ucleotides are the building blocks of nucleic acids.  As shown above, nucleotides consist of three components: (1) a sugar, (2) a phosphate group, and (3) a base. RNA uses ribose sugar while DNA uses deoxyribose sugar.  The  phosphate group, a denosine triphosphate (ATP), stores energy for chemical reactions and   regulates the enzymatic role of proteins, marking them as active or inactive. T here are five different bases that  are used.  RNA uses adenine, uracil, cytosine or guanine (AUCG) and DNA uses adenine, thymine, cytosine and guanine (ATCG). 
    ::核糖核酸是核糖的构件,如上所示,核酸由三部分组成sad1)糖,(2)磷酸组和(3)基;RNA在DNA使用脱氧核糖时使用糖;磷酸组、腺素三磷酸(ATP),储存化学反应能量,调节蛋白的酶作用,标记它们为活性或非活动性;使用五种不同基。RNA使用、、、或guanine(AUCG),而DNA使用、甲状腺、和。

    Nucleotide  bases fall into two categories: double-ringed purines (A,G) and single-ring pyrimidines (C, T, U).   These different bases are shown in the    below . B iologists named some of these bases after  the material where they were discovered. For instance, guanine was first discovered from guano, a fancy name for bird poop.
    ::核糖核酸基可分为两类:双环纯(A,G)和单环(C,T,U)。这些不同的基点如下文所示。生物学家在发现这些基点的材料后点出了其中的一些基点。例如,guanine最初是从瓜诺发现的,这是鸟粪的奇特名称。

     

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    The five bases known to be used in nucleotides, separated into purines, with two rings (left), and pyrimidines, with one ring (right). A dotted, blue line indicates where each base binds to the sugar component. In the absence of a sugar, a hydrogen atom is bound there instead. Thymine is used in DNA while uracil is specific to RNA. The other three bases are used in both RNA and DNA. What is the only difference between thymine and uracil?
    ::已知用于核糖核酸的5个基底被分离成纯碱,有2个环(左),有1个(右),有1个(西米丁),有5个基底。一条虚线显示每个基座与糖成分的结合位置。在没有糖的情况下,氢原子就在那里被捆绑。甲氨基在DNA中使用,而甲氨基是RNA特有的。另外3个基座在RNA和DNA中都使用。甲胺和甲氨基的唯一区别是什么?

    The phosphate group  consists of   a phosphorus atom bound to four oxygen atoms and contains many high energy bonds. When energy is needed for a chemical reaction, one of the phosphate bonds is broken, converting  ATP to  ADP, adenosine diphosphate, with only two phosphate groups remaining. ATP is the most widely used energy carrier in all living  organisms on Earth.
    ::磷酸盐组由磷原子组成,该组由4个氧原子组成,含有许多高能量联结,当化学反应需要能量时,磷酸盐组分之一被打破,将ATP转化为ADP,二磷酸乙烷,只剩下2个磷酸酯组,ATP是地球上所有活生物体中最广泛使用的能量载体。

     

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    The chemical structure of ATP. The three phosphate groups are shown in red. What bond breaks to release a phosphate group, which consists of one phosphorus (P) atom and four oxygen (O) atoms?
    ::ATP的化学结构:三个磷酸盐组以红色显示。一个磷酸盐组由1个磷原子和4个氧原子组成,在释放一个磷酸盐组(P)原子和4个氧原子(O)时,用什么联结折断?