微生物1

Chapter 1-2每位同学选做2题。

1、Why do you think viruses are not included in the five kingdoms or three domain system?2、Why are microorganisms so useful to biologists in experimental model?3、What do you think were the most important discoveries in the development ofmicrobiology? Why?4、What do you think are the five most important research areas to pursue in microbiology ?Give reasons for your choice?1、Why do you think viruses are not included in the five kingdoms or three domain system? (建议从生物的基本特征来考虑)Answers: All viruses, even if they possess other constituents , are constructed around a nucleocapsid core (indeed ,some viruses consist only of a nucleocapsid ) . The nucleocapsid is composed of a nucleic acid , either DNA or RNA ,held within a protein coat called the capsid ,which protects viral , genetic material and aids in its transfer between host cells. Because viruses do not have cellular construction , they are not included in the five kingdoms or three domain system .因为不论是五界系统还是三域系统，其生物都有完整的细胞结构，而病毒不具有细胞结构，一些简单的病毒仅由核酸和蛋白质外壳构成，而且病毒不能不能繁殖，只能复制，所以病毒不包括在五界系统或三域系统中。

2、Why are microorganisms so useful to biologists in experimental model?微生物在生命科学研究只所以有着举足轻重的地位与其与其他生物所不具备的结构、生理、遗传等方面的特性有关：1、由于其进化和分类地位处于原始地位，为物种起源、生物进化方面的研究提供了有利的证据2、主要是由于其具有个体小、结构简单、繁殖快、易培养、易变异、分布广、面积大、转化快、生长旺、适应性强等特性为各类实验研究的理想材料，大大推动了生命科学各个领域的飞速发展。

First, Nature has a large amount of microorganisms. They are very small, simple and have short life cycle. There are many kinds of their metabolization . It is easy to culture them in large scale .Moreover, they are apt to be varied and repeated. So biologists can use them easily .Second, microorganisms has the same genetic code as other organisms.Thirdly, microorganisms may live in some extreme environment where other organisms can not live.Thus microorganisms so useful to biologists in experimental model.模式生物要求背景清楚，基因组小，便于测定和分析，可从中获取经验改进技术方法。

微生物个体小、结构简单、生长周期短，易大量培养，易变异，重复性强等优势，十分易于操作。

微生物又有其它生物共有的基本生物学特性：生长、繁殖、代谢共用一套遗传密码，由于高等生物同源的基因。

因此成为研究的模式生物。

微生物具有其他生物不具备的生物学特征，例如可在其他生物无法生存的极端环境下生存和繁殖，具有其他生物不具备的代谢途径和功能，如化能营养厌氧生活生物固氮和不释放氧的光合作用等，反映微生物极其丰富的多样性；具有其他生物共有的基本生物学特性：生长繁殖代谢共用一套遗传密码等，甚至其基因组上含有与高等生物同源的基因，充分反映了生物高度的统一性；个体小结构简单生长周期短易大量培养易变异重复性强等优势，十分易于操作。

Because microorgmisms are small enough,have simple structure,short life cycle,easy for getting numorously,ofen varies and much repetitive.And they have manycommon bioloy properties with high plants and animals.So biologists can usethem to study many problems of high living things.3、What do you think were the most important discoveries in the development ofmicrobiology? Why?我认为为微生物学作出了非常大贡献的有三位科学家，可谓是微生物学的奠基人：1、微生物学家列文虎克，他利用他自制的显微镜观察到了微生物世界，首次揭示了一个崭新的生物世界——微生物界，具有划时代的意义。

2、法国微生物学家巴斯德利用曲颈瓶实验彻底否定了“自生说“，从而建立了病院学说；1877年他研究了鸡霍乱发现病原菌可诱发免疫性，并首次制成了了狂犬疫苗，证实了其免疫学说，为人类防病、治病做出了重大贡献；后又证实了发酵是由微生物引起的3、德国细菌学家柯赫对大量的病原菌进行了研究提出了证明某种微生物是否为某种疾病的病原菌的基本原则——柯赫法则，确定了病原菌与疾病的关系；后在微生物基本实验技术方面作出了突出贡献。

特别是后两位科学家将微生物的研究从形态描述推进到生理学研究阶段，研究了疾病与人类的关系，深刻影响了医学的发展，并建立了分离、培养、接种和灭菌等一系列独特的微生物研究方法。

I think the most important discoveries in the development of microbiology is the discovery of microorganisms. Leeuwenhoek is the first person to observe and describe microorganisms accurately. If without this discovery, we may not recognize the existence of microorganisms exactly. Let alone to other researches and discoveries. 柯赫首创用固体培养基分离纯化微生物用固体培养基分离纯化微生物的技术是进行微生物学研究的基本前体，研究微生物首先要获得纯化的研究对象，从自然界混杂存在的天然微生物群中分离出特定的微生物，是保证微生物学研究正常进行的关键。

Answers : I think the most important discoveries in the development of microbiology are microscopes .Organisms and agents too small to been seen clearly by the unaided eye were called microorganisms . Antony van Leeuwenhoek was the first person to observe and describe microorganisms accurately . His microscopes could magnify around 50 to 300 times , and he may have illuminated his liquid specimens by placing them between two pieces of glass and shining light on them at a 45 angle to the specimens plane . This would have provided a form of dark-field illuminated and made bacteria clearly visible . Beginning in 1673 Leeuwenhoek sent detailed letters describing his discoveries , to the Royal Society of London . It is clear from his descriptions that he saw both bacteria and protozoa . It was the initiation of microbiology .In my opinion,the spontaneous generation experiment showing that lactic acid fermentation is due to a microorganism. I think it is a revolution in microbiology field. Because spontaneous generation showing that living organisms could develop from nonliving matter. If Pasteur have not overturned this theory,nowadays, peoplemaystill think it is a nonliving matter can make a living organism .This discover made people who studied in microbiology turned to the right direction.I think the swan neck flask experiment is the most important discovery.because ithad beaten the Spontaneous Generation.it let microorganism facing a newlook,facilitating the development of microorganism.4、What do you think are the five most important research areas to pursue in microbiology ? Give reasons for your choice?我认为可以推动微生物学的重大事件有：一：Hershey and Chase 发现噬菌体将DNA注入宿主细胞这一重大发现，揭示出，核酸是细胞的遗传信息的携带者，是遗传物质的基础。