4.2 发现细胞和细胞理论
章节大纲
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A Big Blue Cell
::大蓝细胞What is this incredible object? Would it surprise you to learn that it is a human ? The cell is actually too small to see with the unaided eye. It is visible here in such detail because it is being viewed with a very powerful . Cells may be small in size, but they are extremely important to life. Like all other living things, you are made of cells. Cells are the basis of life, and without cells, life as we know it would not exist. You will learn more about these amazing building blocks of life in this section.
::这个令人难以置信的物体是什么?你是否惊讶地知道它是一个人类?这个细胞其实太小了,无法用无助的眼睛看到它?它在这里非常详细,因为它被用一个非常强大的 。细胞的大小可能很小,但对于生命极为重要。和所有其他生物一样,它们也是细胞的构成。细胞是生命的基础,没有细胞,生命是我们所知道的不存在的。你会在这个部分更多地了解生命的这些惊人的构件。What Are Cells?
::什么是细胞?If you look at living matter with a microscope — even a simple light microscope — you will see that it consists of cells. Cells are the basic units of the structure and function of living things. They are the smallest units that can carry out the processes of life. All organisms are made up of one or more cells, and all cells have many of the same structures and carry out the same basic life processes. Knowing the structure of cells and the processes they carry out is necessary to an understanding of life itself.
::如果你用显微镜——甚至简单的光显微镜——来看待活物,你会看到它是由细胞组成的。细胞是生命结构和功能的基本单位。细胞是能够进行生命过程的最小单位。所有生物体都由一个或多个细胞组成,所有细胞都有许多相同的结构,并进行同样的基本生活过程。了解细胞的结构及其执行的过程对于了解生命本身是必要的。Discovery of Cells
::发现单元格The first time the word cell was used to refer to these tiny units of life was in 1665 by a British scientist named Robert Hooke. Hooke was one of the earliest scientists to study living things under a microscope. The microscopes of his day were not very strong, but Hooke was still able to make an important discovery. When he looked at a thin slice of cork under his microscope, he was surprised to see what looked like a honeycomb. Hooke made the drawing in the figure to show what he saw. As you can see, the cork was made up of many tiny units. Hooke called these units cells because they resembled cells in a monastery.
::1665年,英国科学家罗伯特·胡克首次用单词细胞来表示这些微小的生命单位。虎克是最早研究显微镜下生物的科学家之一。他当时的显微镜并不很强大,但虎克仍然能够做出重要的发现。当他看着显微镜下的一小片软木时,他惊讶地看到什么看起来像蜂窝。虎克在图中画了图来显示他所看到的东西。如你所见,软木箱是由许多微小的细胞组成的。虎克将这些细胞称为细胞细胞,因为它们类似于修道院中的细胞。Robert Hooke sketched these cork cells as they appeared under a simple light microscope.
::罗伯特·胡克画了这些软骨细胞的图画, 因为它们出现在一个简单的光显微镜下。Soon after Robert Hooke discovered cells in cork, Anton van Leeuwenhoek in Holland made other important discoveries using a microscope. Leeuwenhoek made his own microscope lenses, and he was so good at it that his microscope was more powerful than other microscopes of his day. In fact, Leeuwenhoek’s microscope was almost as strong as modern light microscopes. Using his microscope, Leeuwenhoek was the first person to observe human cells and .
::罗伯特·胡克(Robert Hooke)在科克发现细胞后不久,荷兰的安东·范·列乌文霍克(Anton van Leeuwenhoek)用显微镜发现了其他重要发现。 利乌文霍克自己制造了显微镜,他非常擅长显微镜,以至于显微镜比他当年的其他显微镜更有威力。 事实上,利乌文霍克的显微镜几乎和现代显微镜一样强大。 利乌文霍克用显微镜观察人类细胞,是第一个观察人类细胞的人。Cell Theory
::细胞理论By the early 1800s, scientists had observed cells of many different organisms. These observations led two German scientists named Theodor Schwann and Matthias Jakob Schleiden to propose cells as the basic building blocks of all living things. Around 1850, a German doctor named Rudolf Virchow was studying cells under a microscope, when he happened to see them dividing and forming new cells. He realized that living cells produce new cells through division. Based on this realization, Virchow proposed that living cells arise only from other living cells.
::1800年代初,科学家们观察到了许多不同的生物细胞,这些观察导致两名德国科学家,即西奥多·施万恩和马蒂亚斯·雅各布·施莱顿提出细胞,作为所有生物的基本构件。 大约1850年,一位名叫鲁道夫·维肖的德国医生在显微镜下研究细胞,他碰巧看到细胞分裂和形成新的细胞。他意识到活细胞通过分裂产生新的细胞。基于这一认识,维肖建议生命细胞只来自其他生物细胞。The ideas of all three scientists — Schwann, Schleiden, and Virchow — led to cell theory, which is one of the fundamental theories unifying all of biology . Cell theory states that:
::所有三位科学家——施万恩、施莱登和维契霍——的思想导致了细胞理论,这是统一所有生物学的基本理论之一。-
All organisms are made of one or more cells.
::所有生物都是由一个或多个细胞组成的。 -
All the life functions of organisms occur within cells.
::生物的所有生命功能都发生在细胞内部。 -
All cells come from existing cells.
::所有细胞都来自现有的细胞。
Seeing Inside Cells
::查看内部单元格Starting with Robert Hooke in the 1600s, the microscope opened up an amazing new world — a world of life at the level of the cell. As microscopes continued to improve, more discoveries were made about the cells of living things, but by the late 1800s, light microscopes had reached their limit. Objects much smaller than cells (including the structures inside cells) were too small to be seen with even the strongest light microscope.
::从1600年代的罗伯特·胡克开始,显微镜打开了一个惊人的新世界——一个细胞层面的生命世界。随着显微镜的不断改善,对生物细胞的发现越来越多,但到了1800年代末,光显微镜达到了极限。 比细胞(包括细胞内结构)小得多的物体太小,甚至最强的显微镜都看不到。Then, in the 1950s, a new type of microscope was invented. Called the electron microscope, it used a beam of electrons instead of light to observe extremely small objects. With an electron microscope, scientists could finally see the tiny structures inside cells. They could even see individual molecules and atoms. The electron microscope had a huge impact on biology. It allowed scientists to study organisms at the level of their molecules, and it led to the emergence of the molecular biology field. With the electron microscope, many more cell discoveries were made. The figure shows how the cell structures called look when scanned by an electron microscope.
::然后,在1950年代,发明了一种新的显微镜。称为电子显微镜,它使用电子束而不是光来观测极小的物体。有了电子显微镜,科学家们终于可以看到细胞内的微小结构。他们甚至可以看到个别的分子和原子。电子显微镜对生物学产生了巨大影响。它使科学家能够按分子水平研究生物体,并导致分子生物学领域的出现。有了电子显微镜,又发现了更多的细胞。图中显示了细胞结构在用电子显微镜扫描时如何叫看。An electron microscope produced this image of the structures inside of a cell.
::电子显微镜生成了细胞内部结构的图像。Structures Shared By All Cells
::所有单元格共享的结构Although cells are diverse, all cells have certain parts in common. These parts include a plasma membrane, cytoplasm , , and .
::虽然细胞是多种多样的,但所有细胞都有某些共同部分。这些部分包括等离子膜、细胞顶板和。-
The
plasma membrane
(
a type of
cell membrane) is a thin coat of
that surrounds a cell. It forms the physical boundary between the cell and its environment. You can think of it as the “skin” of the cell.
::等离子膜(一种细胞膜)是细胞周围的薄外套。它构成细胞与其环境之间的物理边界。你可以把它视为细胞的“皮肤”。 -
Cytoplasm
refers to all of the cellular material inside of the plasma membrane. Cytoplasm is made up of a watery substance called
cytosol
, and it contains other cell structures, such as ribosomes.
::Cytoplasm 指等离子膜内的所有细胞材料。Cytopolasm 由一种称为cytosolm的水物质组成,它含有其他细胞结构,如血清。 -
Ribosomes
are the structures in the cytoplasm
in which
are made.
::Ribocomes是圆柱形结构的构造。 -
DNA
is a
found in cells. It contains the genetic instructions that cells need to make proteins.
::DNA是在细胞中发现的。 它包含基因指示 细胞需要做蛋白质。
These four parts are common to all cells, from organisms as different as bacteria and human beings. How did all known organisms come to have such similar cells? The similarities show that all life on Earth has a common evolutionary history.
::这四个部分是所有细胞共有的,从细菌和人类等不同的生物体来看,这四个部分是所有细胞共有的。所有已知生物体怎么会有类似的细胞?相似之处表明,地球上的所有生命都有共同的进化历史。Summary
::摘要-
Cells are the basic units of structure and function in living things. They are the smallest units that can carry out the processes of life.
::细胞是结构的基本单位,是生活事物的基本功能单位,是能够进行生命过程的最小单位。 -
In the 1600s, Hooke was the first to observe cells from an organism (cork). Soon after, microscopist van Leeuwenhoek observed many other living cells.
::在1600年代,虎克是第一个观察有机体(cork)细胞的人。 不久之后,微生物学家范利乌文霍克(van Leeuwenhoek)发现了许多其他生物细胞。 -
In the early 1800s, Schwann and Schleiden theorized that cells are the basic building blocks of all living things. Around 1850, Virchow
observed
cells dividing. To previous learnings, he added that living cells arise only from other living cells. These ideas led to cell theory, which states that all organisms are made of cells, that all life functions occur in cells, and that all cells come from other cells.
::1800年代初,Schwann和Schleiden认为,细胞是所有生物的基本构件。大约1850年,Virchow观察到了细胞分裂。在以前的学习中,他补充说,活细胞只来自其他生物细胞。这些想法引出了细胞理论,指出所有生物都是细胞组成的,所有生命功能都发生在细胞中,所有细胞都来自其他细胞。 -
It wasn't until the 1950s that scientists could see what was inside the cell. The invention of the electron microscope allowed them to see organelles and other structures smaller than cells.
::直到20世纪50年代,科学家才能看到细胞内的东西。电子显微镜的发明使他们得以看到器官和其他小于细胞的结构。 -
There is variation in cells, but all cells have a plasma membrane, cytoplasm, ribosomes, and DNA. These similarities show that all life on Earth has a common ancestor in the distant past.
::细胞中存在差异,但所有细胞都有一个等离子膜、细胞图层、骨质和DNA。这些相似之处表明,地球上的所有生命在遥远的过去都有一个共同的祖先。
Review
::回顾1. Describe cells.
::1. 描述牢房。2. Explain how cells were discovered.
::2. 解释如何发现细胞。3. Outline the development of cell theory.
::3. 概述细胞理论的发展。4. Identify the structures shared by all cells.
::4. 查明所有细胞共有的结构。5. True or False: Cork is not a living organism.
::5. 真实或假:Cork不是活生物体。6. True or False: Some organisms are made of only one cell.
::6. 真实或假:有些生物只由一个细胞组成。7. True or False: Ribosomes are found outside of the cytoplasm of a cell.
::7. 真实的或假的:在细胞细胞的细胞图层外发现了有色体。8. Proteins are made on _____________ .
::8. 蛋白质的制造日期为_____________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________9. What are the differences between a light microscope and an electron microscope?
::9. 光显微镜和电子显微镜之间有什么区别?10. The first microscopes were made around
::10. 第一个显微镜是围绕a. 1965
::a. 1965年b. 1665
::b. 1665年c. 1950
::c. 1950年d. 1776
::d. 1776年11. Which of these scientists — Anton van Leeuwenhoek; Robert Hooke; Rudolf Virchow — made each of the below discoveries?
::11. 这些科学家中有哪一位——Anton van Leeuwenhoek、Robert Hooke、Rudolf Virchow——分别发现了下列发现?a. observed some of the first cells and first used the term “cell”
::a. 观测到一些第一个单元格,首先使用 " 细胞 " 一词。b. observed the first human cells
::b. 观测第一批人体细胞c. observed cells dividing
::c. 观测到的分离细胞12. Robert Hooke sketched what looked like honeycombs — or repeated circular or square units — when he observed plant cells under a microscope.
::12. Robert Hooke在用显微镜观察植物细胞时,描绘了蜂窝——或反复圆形或平方单元——的外形。a. What is each unit?
::a. 每个单位是哪个单位?b. Of the shared parts of all cells, what makes up the outer surface of each unit?
::b. 在所有电池的共享部分中,每个单元的外表由什么组成?c. Of the shared parts of all cells, what makes up the inside of each unit?
::c. 在所有细胞共有部分中,每个细胞单元的内部组成是什么?Explore More
::探索更多To learn more about cell theory and its history, watch the video below.
::为了更多了解细胞理论及其历史,Watch the video below for an introduction to cells. The video shows animations and microscopic footage of many different types of cells.
::影片展示了许多不同类型的细胞的动画片和微镜片段。 -
All organisms are made of one or more cells.
