案例研究结论:超出单纯的疲劳

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Case Study Conclusion: More Than Just Tired
::案例研究结论:超出单纯的疲劳

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Jasmin discovered that that her extreme fatigue, muscle pain, vision problems, and vomiting were due to problems in her mitochondria, like the damaged mitochondria shown in red in the picture above. Mitochondria are small, membrane-bound organelles found in eukaryotic cells that provide energy for the cells of the body. They do this by carrying out the final two steps of aerobic cellular respiration (the Krebs cycle and electron transport), which is the major way that the human body breaks down the sugar glucose from food into a form of energy cells can use, namely the molecule ATP. 
::Jasmin发现,她的极端疲劳、肌肉疼痛、视力问题和呕吐是由于她的米托乔德里亚问题,如上面图中红色显示的受损的米托乔德里亚,米托贡德里亚是小的,在为身体细胞提供能量的乳胶细胞中发现的含膜的有机体。他们这样做的方式是最后两步有氧细胞呼吸(Krebs循环和电子迁移),这是人体将糖糖糖从食物中分解为能用的一种能量细胞的主要方法,即分子ATP。

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Because mitochondria provide energy for cells, you can probably easily see why Jasmin was experiencing extreme fatigue, particularly after running. Her damaged mitochondria could not keep up with her need for energy, particularly after intense exercise, which requires a lot of additional energy. What is perhaps not so obvious are the reasons for her other symptoms, such as blurry vision, muscle spasms, and vomiting. All of the cells in the body require energy in order to function properly. Mitochondrial diseases can cause problems in mitochondria in any cell of the body, including muscle cells and cells of the nervous system, which includes the brain and nerves. The nervous system and muscles work together to control vision and digestive system functions, such as vomiting, so when they are not functioning properly, a variety of symptoms can emerge. This also explains why Jasmin’s niece, who has a similar mitochondrial disease, has symptoms related to brain function, such as seizures and learning disabilities. Our cells are microscopic, and mitochondria are even tinier — but they are essential for the proper functioning of our bodies. When they are damaged, serious health effects can occur.
::由于微粒体分体能为细胞提供能量,你可以很容易地看到为什么Jasmin特别在跑步后会经历极端疲劳。她受伤的微粒体分体无法满足她的能量需求,特别是在需要大量额外能量的密集锻炼之后。也许不太明显的原因是她的其他症状的原因,比如模糊视力、肌肉抽筋和呕吐。身体中的所有细胞都需要能量才能正常运转。米托松体型疾病可以在身体的任何细胞中引起微粒体分体力问题,包括肌肉细胞和神经系统的细胞,包括大脑和神经系统。神经系统和肌肉一起工作,以控制视觉和消化系统功能,例如呕吐,因此当它们不能正常运转时,就会出现各种症状。这也解释了为什么Jasmin的侄女患有类似的线形体疾病,有与大脑功能有关的症状,如癫痫和学习残疾。我们的细胞是微细胞,而微粒体分体细胞甚至微粒子体分分,而微体分体分体分体功能也更小 —但是当我们身体正常运转的时候,它们就变得很严重。

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One seemingly confusing aspect of mitochondrial diseases is that the type of symptoms, severity of symptoms, and age of onset can vary wildly between people — even within the same family! In Jasmin’s case, she did not notice symptoms until adulthood, while her niece had more severe symptoms starting at a much younger age. This makes sense, however, when you know more about how mitochondrial diseases work.
::线粒体疾病似乎令人困惑的一个方面是,人们之间的症状类型、症状的严重性和发病年龄可能大不相同,即使在同一个家庭也是如此。 在Jasmin的案例中,她直到成年才注意到症状,而她的侄女的症状从年纪更小开始就更为严重。 然而,当你更多地了解线粒体疾病是如何工作的时,这才有意义。

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Inherited mitochondrial diseases can be due to damage in either the DNA in the nucleus of cells or in the DNA in the mitochondria themselves. Recall that mitochondria are thought to have evolved from prokaryotic organisms that were once free-living, but were then infected or engulfed by larger cells. One of the pieces of evidence that supports this endosymbiotic theory is that mitochondria have their own, separate DNA. When the mitochondrial DNA is damaged (or mutated) it can result in some types of mitochondrial diseases. However, these mutations do not typically affect all of the mitochondria in a cell. During cell division, organelles such as mitochondria are replicated and passed down to the new daughter cells. If some of the mitochondria are damaged, and others are not, the daughter cells can have different amounts of damaged mitochondria. This helps explain the wide range of symptoms in people with mitochondrial diseases — even ones in the same family — because different cells in their bodies are affected to different extents. Jasmin’s niece was affected strongly and her symptoms were noticed early, while Jasmin’s symptoms were more mild and did not become apparent until adulthood.
::遗传性肾上腺硬化反应疾病可能是由于细胞核心的DNA或米托乔因德里亚本身的DNA的损伤。回顾一下,mitochondria被认为已经从曾经自由生存但后来被较大细胞感染或吞没的 prokary 生物体中演变而来。支持这一内分泌共生理论的证据之一是,mitochondria有他们自己的、独立的DNA。当细胞核心的DNA受损(或变异)时,它可能导致某些类型的线粒子硬化反应疾病。然而,这些突变通常不会影响细胞中的所有mitochondria。在细胞分裂期间,像mitochondria这样的器官被复制并传给新的女儿细胞。如果某些mostonchondria受到破坏,而另一些则不是,女儿细胞的受损程度会不同。这有助于解释患有线上腺硬体疾病的人的广泛症状 — 即使是同一家族的患者,这些突变异的症状通常不会影响。在细胞分裂的早期,因为不同的症状变得很深的症状,而其身体也受到影响。

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There is still much more that needs to be discovered about the different types of mitochondrial diseases. But by learning about cells, their organelles, how they obtain energy, and how they divide, you should now have a better understanding of the biology behind these diseases.
::还需要发现更多关于不同类型线粒体疾病的信息。 但是,通过了解细胞、其器官、如何获得能量以及它们是如何分化的,你现在应该更好地了解这些疾病背后的生物学。

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Apply your understanding of cells to your own life. Can you think of other diseases that affect cellular structures or functions. Do they  affect people you know? Since your entire body is made of cells, when cells  are damaged or not functioning properly, it can cause a wide variety of health problems.
::把对细胞的理解应用到自己的生活中。你能想到影响细胞结构或功能的其他疾病吗?它们是否影响你认识的人?由于你整个身体是由细胞组成的,当细胞受损或功能不正常时,它可能造成各种各样的健康问题。

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Chapter Summary
::章次摘要

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In this chapter you learned many facts about cells. Specifically, you learned that:
::在本章中,你了解了很多关于细胞的事实。

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• Cells are the basic units of structure and function of living things.
  ::细胞是生命结构和功能的基本单位。
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• The first cells were observed from cork by Hooke in the 1600s. Soon after, van Leeuwenhoek observed other living cells.
  ::胡克在1600年代从软木中观察了第一批牢房,不久之后,范·利乌文豪克又观察了其他生物牢房。
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• In the early 1800s, Schwann and Schleiden theorized that cells are the basic building blocks of all living things. Around 1850, Virchow saw cells dividing, and added his own theory that living cells arise only from other living cells. These ideas led to cell theory, which states that all organisms are made of cells, all life functions occur in cells, and all cells come from other cells.
  ::18世纪初,施瓦恩和施莱登认为细胞是所有生物的基本构件。 1850年左右,维尔克豪看到细胞分裂,并补充了他自己的理论,即生命细胞只来自其他生物细胞。 这些理论引出了细胞理论,指出所有生物都是由细胞组成的,所有生命功能都存在于细胞中,所有细胞都来自其他细胞。
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• The invention of the electron microscope in the 1950s allowed scientists to see organelles and other structures inside cells for the first time.
  ::1950年代电子显微镜的发明 使科学家能够第一次 看见细胞内的器官和其他结构
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• There is variation in cells, but all cells have a plasma membrane, cytoplasm, ribosomes, and DNA.
  ::细胞中存在差异,但所有细胞都有一个等离子膜、细胞托盘、血清和DNA。
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  • The plasma membrane is composed mainly of a bilayer of phospholipid molecules and forms a barrier between the cytoplasm inside the cell and the environment outside the cell. It allows only certain substances to pass in or out of the cell. Some cells have extensions of their plasma membrane with other functions, such as flagella or cilia.
    ::等离子膜主要由两层磷素分子组成,形成细胞内细胞顶板与细胞外环境之间的屏障,只允许某些物质进入或离开细胞,有些细胞的等离子膜有其他功能的延伸,如旗状或硅状。
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  • Cytoplasm is a thick solution that fills a cell and is enclosed by the plasma  membrane. It helps give the cell shape, holds organelles, and provides a site for many of the biochemical reactions inside the cell. The liquid part of the cytoplasm is called cytosol.
    ::Cytoplasm 是一个填充细胞的厚溶液, 由等离子膜封闭。 它有助于给定细胞形状, 握住风琴, 并为细胞内许多生化反应提供一个场所。 cytoplasm 的液态部分被称为 cytobram 。
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  • Ribosomes are small structures where proteins are made.
    ::Riboomes是制造蛋白质的小型结构。
  
  ::等离子膜主要由两层磷素分子组成,形成细胞内细胞细胞与细胞外环境之间的屏障,只允许某些物质进入或离开细胞,有些细胞有其等离子膜的延伸,具有其他功能,如旗形或硅状;相色素是一种填充细胞的厚溶液,并被血浆膜封闭。它有助于形成细胞形状,持有风琴,并为细胞内许多生物化学反应提供一个场所。细胞内液体部分称为细胞素。波纹体是产生蛋白质的小型结构。
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• Cells are usually very small, so they have a large enough surface area-to-volume ratio to maintain normal cell processes. Cells with different functions often have different shapes.
  ::单元格通常很小,因此其面积与体积的比例很大,足以维持正常的细胞过程。 功能不同的细胞往往有不同的形状。
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• Prokaryotic cells do not have a nucleus. Eukaryotic cells have a nucleus, as well as other organelles. An organelle is a structure within the cytoplasm of a cell that is enclosed within a membrane and performs a specific job.
  ::蛋白质细胞没有核。 蛋白质细胞有核和其他有机体。 有机体是细胞细胞细胞细胞内的一种结构,该细胞被封闭在膜内,并从事特定的工作。
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• The cytoskeleton is a highly organized framework of protein filaments and tubules that criss-cross the cytoplasm of a cell. It gives the cell shape  and helps to hold cell structures (such as organelles) in place.
  ::Citoskeleton是一个由蛋白丝和管状组成的高度有组织的框架,它穿过细胞的细胞的细胞图层,使细胞形状形成,并帮助维持细胞结构(如风琴)。
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• The nucleus is the largest organelle in a eukaryotic cell. It is considered to be the cell's control center, and it contains DNA and controls gene expression, including which proteins the cell makes.
  ::核是单体细胞中最大的有机体。 它被认为是细胞的控制中心, 它包含DNA和控制基因表达, 包括细胞产生的蛋白质。
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• The mitochondrion is an organelle that makes energy available to cells. According to the widely accepted endosymbiotic theory, mitochondria evolved from prokaryotic cells that were once free-living organisms that infected or were engulfed by larger prokaryotic cells.
  ::线粒体是向细胞提供能量的有机体。 根据广泛接受的内共生理论,米托昆德里亚从曾经是自由活生物体、感染或吞没较大蛋白细胞的蛋白细胞中演变而来。
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• The endoplasmic reticulum (ER) is an organelle that helps make and transport proteins and lipids. Rough endoplasmic reticulum (RER) is studded with ribosomes. Smooth endoplasmic reticulum (SER) has no ribosomes.
  ::内核内核内核润滑(ER)是一种有助于制造和运输蛋白质和脂质的有机体。 外核内核内核内核内核内核内核内核内核内核内核内核内核内核内核内核内核内核内核内核内核内核内核内核内核内核内核内核内核内核内核内核内核内核内核内核内核内核内核内核内核内核内核内核内核内核内核内核内核内核内核内核内核内核内核内核内核内核内核内核内核内核内核内核内核内核内核内核内核内核内核内核内核内核内核内核内核内核内核内核内核内核内核内核内核外核内核内核内核内核内核内核内核内核内核内核内核内核内核内核内核内核内核内核内核内核内核内核内核内核内核内核内核内核内核内核内核内核内核内核内核内核内核内核内核内核内核内核内核内核内核内核内核内核内核内核内核内核内核内核内核内核内核内核内核内核内核内核内核内核内核内核内核内核内核内核内核内核内核内核内核内核内核内核内核内核内核内核内核内核内核内核内核内核内核内核内核内核内核内核内核内核内核内核内核内核内核内核内核内核内核内核内有内核内核内核内核内核内核内核内核内核内核内核内核内核内核内核内核内核内核内核内核内核内核内核内核内核内核内核内核内核内核内核内核内核内核内核内核内核内核内核内核内核内核内核内核内核内核内核内核内
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• The Golgi apparatus is a large organelle that processes proteins and prepares them for use both inside and outside the cell. It is also involved in the transport of lipids around the cell.
  ::Golgi装置是一个大型有机体,处理蛋白质,准备在细胞内外使用,还参与细胞周围的脂肪运输。
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• Vesicles and vacuoles are sac-like organelles that may be used to store and transport materials in the cell or as chambers for biochemical reactions. Lysosomes and peroxisomes are vesicles that break down foreign matter, dead cells, or poisons.
  ::卵类和真空体是可被用于储存和运输细胞中材料或用作生化反应室的类似天然的有机物,而中性体和过氧体是分裂外物质、死细胞或毒物的卵体。
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• Centrioles are organelles located near the nucleus that help organize the chromosomes before cell division so each daughter cell receives the correct number of chromosomes.
  ::中子体是位于核心附近的有机体,有助于在细胞分裂之前组织染色体,因此每个女儿细胞得到正确的染色体数量。
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• There are two basic ways that substances can cross the cell’s plasma membrane: passive transport (which requires no energy expenditure by the cell) and active transport (which requires energy).
  ::物质可以穿越细胞等离子膜有两种基本途径:被动运输(细胞不需要能源支出)和主动运输(需要能源)。
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• No energy is needed from the cell for passive transport because it occurs when substances move naturally from an area of higher concentration to an area of lower concentration. Types of passive transport in cells include:
  ::被动运输不需要从电池中取用能量,因为当物质从高浓度地区自然移动到低浓度地区时,就不需要从电池中取用能量。

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  • Simple diffusion, which is the movement of a substance due to differences in concentration without any help from other molecules. This is how very small, hydrophobic molecules, such as oxygen and carbon dioxide, enter and leave the cell.
    ::简单的扩散,即一种物质由于浓度差异而在没有任何其他分子帮助的情况下移动。这就是氧和二氧化碳等微小的疏水分子进入和离开细胞的方式。
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  • Osmosis, which is the diffusion of water molecules across the membrane.
    ::骨质疏松,即水分子在膜上扩散。
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  • Facilitated diffusion, which is the movement of a substance across a membrane due to differences in concentration, but only with the help of transport proteins in the membrane (such as channel proteins or carrier proteins). This is how large or hydrophilic molecules and charged ions enter and leave the cell.
    ::便利扩散,即一种物质由于浓度差异而在膜上移动,但只有在膜上运输蛋白(如通道蛋白或载体蛋白)的帮助下,才能通过膜上移动,即物质在膜上移动,即大型或流体性分子和充电离子进入和离开细胞的方式。
  
  ::简单的扩散,即一种物质由于浓度差异而在没有任何其他分子帮助的情况下移动,这是一种物质由于浓度差异而产生的运动。这就是氧和二氧化碳等微小的疏水分子进入和离开细胞的方式。Osmosis,即水分子跨膜扩散。促进扩散,即一种物质由于浓度差异而在膜上移动,但只是在膜上运输蛋白的帮助下(如通道蛋白或载体蛋白)才能进入和离开细胞。这就是大型或流体分子和充电离子进入和离开细胞的方式。
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• Active transport requires energy to move substances across the plasma membrane, often because the substances are moving from an area of lower concentration to an area of higher concentration or because of their large size. Two examples of active transport are the sodium-potassium pump and vesicle transport.
  ::活性运输需要能量将物质通过等离子膜移动,这往往是因为这些物质正在从低浓度地区转移到高浓度地区,或者由于其体积大。
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  • The sodium-potassium pump moves sodium ions out of the cell and potassium ions into the cell, both against a concentration gradient, in order to maintain the proper concentrations of both ions inside and outside the cell and to thereby control membrane potential.
    ::钠-钾泵将钠离子从细胞中移出,将钾离子移入细胞中,两者都对着浓度梯度,以便保持细胞内外离子的适当浓度,从而控制膜潜力。
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  • Vesicle transport uses vesicles to move large molecules into or out of cells.
    ::输卵器运输使用输卵器将大分子运入或运出细胞。
  
  ::钠-钾泵将钠离子从细胞中移出,并将钾离子移入细胞中,两者都对着浓度梯度,以便保持细胞内外的离子的适当浓度,从而控制膜潜力。
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• Energy is the ability to do work. It is needed by every living cell to carry out life processes.
  ::能源是工作的能力,每个生物细胞都需要能源来执行生命过程。
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• The form of energy that living things need is chemical energy, and it comes from food. Food consists of organic molecules that store energy in their chemical bonds.
  ::生物需要的能量形式是化学能源,它来自食物。 食物由有机分子组成,它们将能量储存在化学链条中。
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• Autotrophs (producers) make their own food. Think of plants that make food by photosynthesis. Heterotrophs (consumers) obtain food by eating other organisms.
  ::自发(自发(productors))自制食物。 想想那些通过光合作用制造食物的植物。 食用其他生物来获取食物的食用者( 消费者 ) 。
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• Organisms mainly use the molecules glucose and ATP for energy. Glucose is the compact, stable form of energy that is carried in the blood and taken up by cells. ATP contains less energy and is used to power cell processes.
  ::有机体主要使用分子甘蔗和ATP作为能量,甘蔗是紧凑、稳定的能量形式,由血液携带,由细胞吸收。ATP含有较少的能量,用于电动细胞过程。
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• The flow of energy through living things begins with photosynthesis, which creates glucose. The cells of organisms break down glucose and make ATP.
  ::生物体的能量流动从光合作用开始,产生葡萄糖。 生物细胞分解葡萄糖,形成ATP。

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• Cellular respiration is the aerobic process by which living cells break down glucose molecules, release energy, and form molecules of ATP. Overall, this three-stage process involves glucose and oxygen reacting to form carbon dioxide and water.
  ::细胞呼吸是活细胞分解葡萄糖分子、释放能量和形成ATP分子的有氧过程。 总体而言,这三阶段过程包括葡萄糖和氧气反应以形成二氧化碳和水。
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  • The first stage of cellular respiration, called glycolysis, takes place in the cytoplasm. In this step, enzymes split a molecule of glucose into two molecules of pyruvate, which releases energy that is transferred to ATP.
    ::细胞呼吸的第一阶段,即所谓的淋巴解析,发生在细胞图层中。在这一步骤中,酶将葡萄糖的分子分裂成两个颗粒分子,释放能量,转移到ATP。
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  • The second stage of cellular respiration, called the Krebs cycle, takes place in the matrix of a mitochondrion. During this stage, two turns through the cycle result in all of the carbon atoms from the two pyruvate molecules forming carbon dioxide and the energy from their chemical bonds being stored in a total of 16 energy-carrying molecules (including four from glycolysis).
    ::细胞呼吸的第二阶段,即叫做Krebs循环的细胞呼吸的第二阶段,在米托昆德里翁的基质中进行。在这个阶段,两轮循环的结果是,形成二氧化碳的两个闪烁分子的所有碳原子及其化学键的能量都储存在总共16个含有能量的分子中(包括4个来自玻璃解析的分子)。
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  • The third stage of cellular respiration, called electron transport, takes place on the inner membrane of the mitochondrion. Electrons are transported from molecule to molecule down an electron-transport chain. Some of the energy from the electrons is used to pump hydrogen ions across the membrane, creating an electrochemical gradient that drives the synthesis of many more molecules of ATP.
    ::细胞呼吸的第三阶段,即所谓的电子传输,发生在米托昆德里翁的内膜上。电子从分子转移到电子运输链下的分子。电子产生的一些能量被用于泵打膜的氢离子,形成电化学梯度,驱动APT中更多分子的合成。
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  • In all three stages of aerobic cellular respiration combined, as many as 38 molecules of ATP are produced from just one molecule of glucose.
    ::在有氧细胞呼吸结合的所有三个阶段中,最多38个ATP分子仅从一个葡萄糖分子中产生。
  
  ::细胞呼吸的第一阶段,称为淋巴分解,在细胞图层中发生。在这一步骤中,酶将葡萄糖的分子分裂成两个颗粒分子,这些分子释放能量到ATP。细胞呼吸的第二阶段,称为Krebs循环,在线粒体的基体中发生。在这个阶段,两个循环过程的结果是,由形成二氧化碳和其化学联结的能量组成的两个颗粒分子形成的所有碳原子,储存在总共16个含有能量的分子中(包括4个来自玻璃解剖的分子)中。细胞呼吸的第三阶段,称为电子传输,在线粒体的内膜中发生。电从分子转移到分子到电子运输链下方的分子中。电子中的某些能量被用于在整个模子层泵氢离,产生一种电化学梯度,驱动着更多含有ATP的分子合成。在ATP的所有三个阶段中,称为电子迁移的细胞呼吸系统,作为ATP的一个分子分子混合体,在ATP生产的所有三个阶段中,电从一个分子分子分子的分子中,作为一个分子分子分子的分子的合成。
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• Some organisms can produce ATP from glucose by anaerobic respiration, which does not require oxygen. Fermentation is an important type of anaerobic process . There are two types: alcoholic fermentation and lactic acid fermentation. Both start with glycolysis.
  ::有些有机体通过厌氧呼吸而产生甘蔗糖的ATP,不需要氧气呼吸。发酵是厌氧过程的一个重要类型。有两种类型:酒精发酵和电酸发酵。这两种类型都以液解作用开始。
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  • Alcoholic fermentation is carried out by single-celled organisms, including yeasts and some bacteria. We use alcoholic fermentation in these organisms to make biofuels, bread, and wine.
    ::酒精发酵由单细胞生物进行,包括酵母和一些细菌,我们使用这些生物中的酒精发酵来制造生物燃料、面包和葡萄酒。
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  • Lactic acid fermentation is undertaken by certain bacteria, including the bacteria in yogurt, and also by our muscle cells when they are worked hard and fast.
    ::某些细菌,包括酸奶中的细菌,以及我们的肌肉细胞,在努力和快速工作时,进行法酸发酵。
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  • Anaerobic respiration produces far less ATP than does aerobic cellular respiration, but it has the advantage of being much faster.
    ::与有氧细胞呼吸相比,有氧呼吸产生的ATP 远远低于ATP,但它的优点是速度快得多。
  
  ::酒精发酵由单细胞生物进行,包括酵母和某些细菌。我们使用这些生物中的酒精发酵来制造生物燃料、面包和葡萄酒。 包括酸酸细菌在内的某些细菌在酸酸发酵时进行,以及我们肌肉细胞在辛勤和快速工作时进行。 厌氧呼吸比有氧细胞呼吸产生ATP要少得多,但它的优点是速度要快得多。
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• The cell cycle is a repeating series of events that includes growth, DNA synthesis, and cell division.
  ::细胞循环是一系列重复的事件,包括生长、DNA合成和细胞分裂。
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• In a eukaryotic cell, the cell cycle has two major phases: interphase and mitotic phase. During interphase, the cell grows, performs routine life processes, and prepares to divide. During mitotic phase, first the nucleus divides (mitosis) and then the cytoplasm divides (cytokinesis), which produces two daughter cells.
  ::在eukaryatic细胞中,细胞循环有两个主要阶段:间和线性阶段。在间阶段,细胞生长,进行正常的生活过程,并准备分裂。在线性阶段,先是核分裂(分裂 ) , 然后是细胞托盘分裂(细胞化 ) , 产生两个女儿细胞。
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  • Until  a eukaryotic cell divides, its nuclear DNA exists as a grainy material called chromatin. After DNA replicates and the cell is about to divide, the DNA condenses and coils into the X-shaped form of a chromosome. Each chromosome consists of two sister chromatids, which are joined together at a centromere.
    ::直到衣原体细胞分裂,其核DNA作为称为染色体的质状材料存在。在DNA复制和细胞即将分离后,DNA凝结和卷圈形成染色体的X形形式。每个染色体由两个姐妹染色体组成,在半色谱处结合。
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  • During mitosis, sister chromatids separate from each other and move to opposite poles of the cell. This happens in four phases: prophase, metaphase, anaphase, and telophase.
    ::在分裂期间,姐妹染色体彼此分离,移到细胞的对角,这分为四个阶段:前期、后期、后期、后期和调频。
  
  ::直到衣原体细胞分裂,其核DNA作为称为染色素的质状材料存在。在DNA复制和细胞即将分离后,DNA凝结和凝结将形成染色体的X形形式。每种染色体由两个姐妹染色体组成,两个姐妹染色体放在一个半色体内结合。在分裂症期间,姐妹染色体彼此分离并移动到细胞的对面极。这分四个阶段发生:预相、元相、止相和调相。
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• The cell cycle is controlled mainly by regulatory proteins that signal the cell to either start or delay the next phase of the cycle at key checkpoints.
  ::细胞循环主要由监管性蛋白质控制,这些蛋白质表示细胞要么在关键检查站开始,要么推迟周期的下一阶段。
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• Cancer is a disease that occurs when the cell cycle is no longer regulated, often  because the cell's DNA has become damaged. Cancerous cells grow out of control and may form a mass of abnormal cells called a tumor.
  ::癌症是一种在细胞循环不再受管制时发生的疾病,经常是因为细胞的DNA受损。 癌症细胞发展失控,并可能形成被称为肿瘤的异常细胞。

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In this chapter, you learned about cells and some of their functions, as well as how they pass genetic material in the form of DNA to their daughter cells. In the next chapter, you will learn how DNA is passed down to offspring, which causes traits to be inherited. These traits may be innocuous (such as eye color) or detrimental (such as mutations that cause disease). The study of how genes are passed down to offspring is called genetics, and as you will learn in the next chapter, this is an interesting topic that is highly relevant to human health.
::在本章中,你了解了细胞及其部分功能,以及它们如何以DNA的形式将遗传物质传递给后代细胞。在下一章中,你将了解如何将DNA传给后代,从而导致遗传特征的传承。这些特征可能是无害的(例如眼睛颜色)或有害(例如导致疾病的突变)。研究基因如何传递给后代的问题被称为遗传学,正如你将在下一章中了解到的那样,这是一个与人类健康高度相关的有趣话题。

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Chapter Summary Review
::" 概述 " 章次

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1. Choose whether each  description applies to eukaryotic cells, prokaryotic cells, or both:
::1. 选择每一说明是否适用于表情细胞、蛋白质细胞,还是两者兼有:

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a. has a nuclear membrane
::a. 具有核膜

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b. has a plasma membrane made of a phospholipid bilayer
::b. 由磷素双层人制成的等离子膜

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c. can be in a multicellular organism
::c. 可在多细胞有机体中

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d. has ribosomes
::d. 有血压

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e. has an endoplasmic reticulum
::e. 具有内层透镜性中心润滑剂

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f. DNA replicates before cell division
::f. 在细胞分裂之前复制DNA

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g. has a single circular chromosome
::g. 具有单环染色体

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h. has cytoplasm that splits into two daughter cells during cell division
::h. 具有细胞分裂期间分裂成两个女儿细胞的细胞细胞。

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i. has a cell cycle that includes interphase and mitosis
::i. 具有细胞循环,包括中继和分裂

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j. the type of cell that most likely evolved to become mitochondria
::j. 最有可能演变为米多支离子体的细胞类型

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2. Name one example of a prokaryotic organism and one example of a eukaryotic organism.
::2. 举一个蛋白质有机体的例子和一个蛋白质有机体的例子。

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3. Neurons are cells in the nervous system that transmit messages. They use energy to maintain the balance of sodium and potassium ions inside and outside of them, which is critical for their ability to send messages.
::3. 中子是神经系统中传递信息的细胞,它们利用能量来保持其内外钠离子和钾离子的平衡,这对于它们发送信息的能力至关重要。

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a. What kind of transport is this maintenance of sodium and potassium ion concentrations: active or passive? Explain your reasoning.
::a. 这种维持钠和钾离子浓度的运输方式是:主动还是被动?

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b. What creates the barrier between the inside and the outside of these cells?
::b. 是什么造成这些牢房内外之间的屏障?

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c. What molecule uses energy to maintain the balance of sodium and potassium ions inside and outside of neurons? Describe two reasons why a molecule like this is required.
::c. 哪些分子利用能量来维持神经元内外钠离子和钾离子的平衡?

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d. What form of energy is used in this process?
::d. 在这一过程中使用了何种能源形式?

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e. Briefly explain how the energy in the food you eat gets there, and how it provides energy for your neurons in the form necessary to power this process.
::e. 简要解释您所食食物的能量是如何到达那里的,以及如何以驱动这一进程所需的形式为您的神经元提供能量。

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4. Explain why the inside of the plasma membrane — the side that faces the cytoplasm of the cell — must be hydrophilic.
::4. 解释为什么等离子膜的内侧,即面对细胞的细胞顶板的侧面,必须是水利的。

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5. True or False:  Anaerobic and aerobic cellular respiration both produce ATP.
::5. 真实或假:有氧和有氧细胞呼吸均产生ATP。

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6. True or False:  The membrane surrounding a cell can also be called the plasma membrane.
::6. 真实或假:细胞周围的膜也可以称为等离子膜。

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7. True or False:  Each phospholipid molecule in the cell membrane has two heads and a tail.
::7. 真实或假的:细胞膜中的每种磷素分子都有两头和尾。

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8. True or False:  For cells, a smaller size is generally more efficient.
::8. 真实或假:对于细胞而言,较小尺寸一般更有效率。

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9. True or False:  DNA is located in the nucleus of prokaryotic cells.
::9. 真实或假:DNA位于蛋白质细胞核心。

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10. True or False:  Cilia and flagella stick out of the cell membrane, but are not made of cell membrane themselves.
::10. 真实或假:Cilia和Fangella坚持从细胞膜中出来,但不是细胞膜本身。

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11. Which of the below statements  about the plasma membrane is false?
::11. 以下关于等离子膜的哪些说明是虚假的?

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a. It encloses the cytoplasm.
::a. 含有细胞顶板。

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b. It protects and supports the cell.
::b. 它保护和支持电池。

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c. It keeps all external substances out of the cell.
::c. 将所有外部物质排除在细胞之外。

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d. none of the above
::d. 以上无任何内容

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12. During diffusion, substances move from an area of ____________ concentration to an area of ___________ concentration.
::12. 在扩散过程中,物质从浓度地区转移到浓度地区。

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a. higher, lower
::a. 高,低

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b. lower, higher
::b. 低,高

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c. higher, equal
::c. 更高、相等

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d. lower, equal
::d. 较低、相等

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13. Which process produces glucose?
::13. 哪种过程产生葡萄糖?

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a. anaerobic respiration
::a. 厌氧呼吸

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b. aerobic cellular respiration
::b. 有氧细胞呼吸

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c. photosynthesis
::c. 光合作用

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d. fermentation
::d. 发酵

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14.    a. Which type of respiration involves electron transport?
::14.a. 哪种类型的呼吸涉及电子运输?

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b. Where does this electron transport occur within the cell?
::b. 这种电子运输在电池内在何处?

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c. Energy from electron transport is used to pump hydrogen ions across a membrane. Is this active or passive transport of the hydrogen ions? Explain your answer.
::c. 电子运输产生的能量用于将氢离子泵过膜,这是氢离子主动或被动运输吗?解释你的答复。

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d. After the process described in part c, hydrogen ions then flow from a region of higher concentration to a region of lower concentration. Is this active or passive transport of the hydrogen ions? Explain your answer.
::d. 在C部分所述过程之后,氢离子从高浓度区域流向低浓度区域,这是氢离子主动还是被动迁移?解释你的答复。

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15. Explain the relationships between interphase, mitosis, and cytokinesis.
::15. 解释中间阶段、分裂症和细胞外科疾病之间的关系。