5.1病毒
Section outline
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What causes the common cold?
::是什么导致普遍寒冷?That miserable cough and runny nose is caused by one villain: a virus. Viruses come in many different shapes, including the prickly balls you see here. They are so tiny that they can only be seen with a very powerful .
::令人痛苦的咳嗽和鼻涕是由一个恶棍造成的:病毒。病毒以多种不同的形式出现,包括你在这里看到的刺痛的球。它们太小,只能用非常强大的力量才能看到。What is a Virus?
::什么是病毒?We have all heard of viruses. The flu, the common cold, and many other diseases are caused by viruses. But what is a virus? Do you think viruses are living? Which do they belong to? Bacteria ? ? Eukarya ?
::我们都听说过病毒。流感、普通寒冷和许多其他疾病都是由病毒引起的。但病毒是什么?你认为病毒是活的吗?病毒属于什么?细菌?Are Viruses Alive?
::病毒还活着吗?The answer is actually “no.” A virus is essentially or surrounded by a coat of protein ( Figure ). It is not made of a cell , and cannot maintain a stable internal environment ( ). Recall that a cell is the basic unit of living organisms . So if a virus is not made of at least one cell, can it be living? Viruses also cannot reproduce on their own—they need to infect a host cell to reproduce. So a virus is very different from any of the organisms that fall into the three domains of life.
::答案其实是“不 ” 。 病毒在本质上或周围被蛋白层(图)所包围。 它不是细胞制造的,无法维持稳定的内部环境 ()。 回顾一个细胞是活生物体的基本单位。 所以,如果一个病毒不是由至少一个细胞制造的,那么它能活吗?病毒也不能自己繁殖,它们需要感染宿主细胞才能繁殖。 因此,病毒与属于生命三个领域的任何生物非常不同。Though viruses are not considered living, they share two important traits with living organisms. They have genetic material like all cells do (though they are not made of cells), and they can evolve. The genetic material of a virus can change (mutate), altering the traits of the virus. As the process of evolution has resulted in all life on the planet today, the of viruses has been controversial. It calls into question the very definition of life.
::尽管病毒不被认为是活的,但它们与活生物体有着两个共同的重要特征。它们拥有像所有细胞一样的遗传物质(尽管它们不是细胞制造的 ) , 并且它们可以演化。病毒的遗传物质可以改变(变异 ) , 改变病毒的特性。随着进化过程导致今天地球上的所有生命,病毒已经引起了争议。它使人们质疑生命的定义本身。These little "alien" looking creatures are viruses, and these specific viruses infect Escherichia coli bacteria. Shown is a representation of viruses infecting a cell. The virus lands on the outside of the cell and injects its genetic material into the cell. Replication
::复制复制Viruses infect a variety of organisms, including plants, animals , and bacteria, injecting its genetic material into a cell of the host organism. Once inside the host cell, they use the cell’s own ATP (energy), ribosomes , enzymes , and other cellular parts to make copies of themselves. The host cell makes a copy of the viral DNA and produces viral proteins. These are then packaged into new viruses. So viruses cannot replicate or reproduce on their own; they rely on a host cell to make additional viruses.
::病毒感染了各种生物,包括植物、动物和细菌,将其遗传物质注入宿主生物的细胞中。 一旦进入宿主细胞,它们就会使用细胞本身的ATP(能量 ) 、 核糖核酸、酶和其他细胞部件来复制自己。宿主细胞复制病毒DNA并产生病毒蛋白。 然后这些病毒被包装成新的病毒。 因此病毒无法自行复制或复制;它们依靠宿主细胞制造更多的病毒。Viruses and Human Disease
::病毒和人类疾病Viruses cause many human diseases. In addition to the flu and the common cold, viruses cause rabies, diarrheal diseases, AIDS , cold sores, and many other diseases ( Figure ). Viral diseases range from mild to fatal.
::病毒造成许多人类疾病,除了流感和普通寒冷之外,病毒还造成狂犬病、腹泻病、艾滋病、寒痛和许多其他疾病(图)。Cold sores are caused by a herpes virus. Summary
::摘要-
A virus is composed of DNA or RNA surrounded by a coat of protein.
::一种病毒由DNA或RNA组成,周围环绕着一种蛋白层。 -
Viruses are not considered living things because they cannot reproduce on their own, and they are not comprised of cells.
::病毒不被视为活物,因为它们不能自己繁殖,也不由细胞组成。
Explore More
::探索更多Use the resources below to answer the questions that follow.
::利用以下资源回答以下问题。Explore More I
::探索更多-
Viruses
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::病毒在(8:06)
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How do viruses reproduce? How does this differ from other organisms?
::病毒是如何繁殖的?这与其他生物有何不同? -
What kinds of nucleic acids can viruses have?
::病毒能有哪种核酸? -
Explain one of the theories as to how viruses came to be.
::解释一下病毒是如何出现的一个理论。 -
What is the importance of the "envelope" to a virus? What is the envelope made of?
::"信封"对病毒有什么意义?信封是用什么做的? -
What is a difference between the lytic cycle of a virus and the lysogenic cycle?
::病毒的淋巴循环和诱发性循环之间有什么区别?
Explore More II
::探索更多情况二-
How Flu Viruses Attack
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::流感病毒如何攻击(3:48)
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What is one way a flu virus can kill a human?
::流感病毒以什么方式可以杀死人类? -
Do mutations make viruses more deadly? Why or why not?
::突变会增加病毒的致命性吗?
Review
::回顾-
Is a virus a living thing? Why or why not?
::病毒是活物吗? -
Name four examples of human diseases caused by a virus.
::举四例说明病毒引起的人类疾病。
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A virus is composed of DNA or RNA surrounded by a coat of protein.