5.15 遗传工程
Section outline
-
Please Pass the Potatoes
::请过马铃薯You might want to pass on the potato plants on the right in this photo . They are infected with a , which is quickly killing them. The potato plants on the left are healthy and productive. Why aren't they infected with the same virus? The plants on the left have been genetically engineered to make them resistant to the virus.
::左边的马铃薯植物是健康和有生产力的。为什么他们没有感染同样的病毒?左边的马铃薯植物是经过基因改造的,以使它们抗病毒。What Is Genetic Engineering?
::什么是遗传工程?Genetic engineering is the use of technology to change the genetic makeup of living things for human purposes. Generally, the goal of genetic engineering is to modify organisms so they are more useful to humans. G enetic engineering, for example, may be used to create crops that yield more food or resist insect pests or viruses, such as the virus-resistant potatoes pictured above. Research is also underway to use genetic engineering to cure human with .
::基因工程是利用技术改变人类生物的基因构成,一般而言,基因工程的目标是改变生物体,使其对人类更有用。例如,基因工程可以用来创造作物,生产更多的食物或抵抗昆虫病虫害或病毒,如上面描绘的抗病毒土豆。 基因工程还正在进行研究,利用基因工程治疗人类。Genetic Engineering Methods
::遗传工程方法G enetic engineering uses a variety of techniques to achieve its aims. Two commonly used techniques are gene cloning and the polymerase chain reaction .
::遗传工程利用各种技术实现其目标,两种常用技术是基因克隆和聚合酶链反应。Gene Cloning
::Gene 克隆Gene cloning is the process of isolating and making copies of a gene . This is useful for many purposes. For example, gene cloning might be used to isolate and make copies of a normal gene for gene therapy. Gene cloning involves four steps: isolation, ligation , transformation, and selection.
::基因克隆是分离和复制基因的过程,对许多目的都有用,例如,基因克隆可用于分离和复制基因疗法的正常基因。基因克隆包括四个步骤:隔离、捆绑、转化和选择。-
In the
isolation
step, an
is used to break
at a specific base sequence. This is done to isolate a gene.
::在孤立步骤中, 使用 an 来打破特定的基数序列。 这是用来分离基因的 。 -
During
ligation
, the enzyme
DNA ligase
combines the isolated gene with
plasmid
DNA from
. (Plasmid DNA is circular DNA that is not part of a
and can replicate independently.) Ligation is illustrated in the figure
. The DNA that results is called
.
::在捆绑期间,酶DNA链将孤立的基因与来自......的颗粒式DNA结合起来。 (彩虹式DNA是圆形DNA,不是一种DNA的一部分,可以独立复制。 )解剖在图中说明。结果的DNA被称为 。 -
In
transformation
, the recombinant DNA is inserted into a living
, usually a bacterial cell.
::在转化过程中,重组DNA被插入活细胞,通常是细菌细胞。 -
Selection
involves growing transformed bacteria to make sure they have the recombinant DNA. This is a necessary step because transformation is not always successful. Only bacteria that contain the recombinant DNA are selected for further use.
::选择涉及生长变异细菌以确保它们拥有重组DNA。 这是必要的一步, 因为转换并不总是成功。 只有含有重组DNA的细菌才被选中供进一步使用 。
Ligation. DNA ligase joins together an isolated gene and plasmid DNA. This produces recombinant DNA.
::脱氧核糖核酸 DNA离子酶结合了一种孤立的基因 和颗粒的DNA 产生重组的DNAPolymerase Chain Reaction
::聚合酶链反应The polymerase chain reaction (PCR) makes many copies of a gene or other DNA segment. This might be done in order to make large quantities of a gene for genetic testing. involves three steps: denaturing , annealing , and extension . The three steps are illustrated in the figure . They are repeated many times in a cycle to make large quantities of the gene.
::聚合酶链反应(PCR)复制了许多基因或其他DNA部分,这可以是为了将大量基因用于基因测试。这涉及三个步骤:衰落、渗入和扩展。图中说明了这三个步骤。它们在一个周期中重复多次,以产生大量基因。-
Denaturing
involves heating DNA to break the bonds holding together the two DNA strands, yielding two single strands of DNA.
::拒绝使用涉及取暖DNA,以打破将两个DNA链捆在一起的纽带,产生两个单一的DNA线。 -
Annealing
involves cooling the single strands of DNA and mixing them with short DNA segments called
primers
. Primers have base sequences that are complementary to segments of the single DNA strands. As a result, bonds form between the DNA strands and primers.
::Annaling涉及冷却单一的DNA片段,并将其与称为基质的短DNA片段混为一谈。 基级序列与单一DNA片段相辅相成。 因此,DNA片段和基质之间形成了联系。 -
Extension
occurs when an enzyme (
Taq polymerase
or Taq DNA polymerase) adds
nucleotides
to the primers. This produces new DNA molecules, each incorporating one of the original DNA strands.
::当酶(Taq聚合酶或Taq DNA聚合酶)在基质中添加核素时,就会发生延展,从而产生新的DNA分子,每个分子都含有原有的DNA链。
The Polymerase Chain Reaction. The polymerase chain reaction involves three steps, and high temperatures are needed for the process to work. The enzyme Taq polymerase is used in step three because it can withstand high temperatures.
::聚合酶链反应。聚合酶链反应包括三个步骤,并且需要高温才能使过程起作用。酶Taq聚合酶在第三步使用,因为它能承受高温。Uses of Genetic Engineering
::利用遗传工程Methods of genetic engineering can be used for many practical purposes. They are used widely in both medicine and .
::遗传工程方法可用于许多实际用途,在医学和医学领域广泛使用。Applications in Medicine
::医学应用In addition to gene therapy for genetic disorders, genetic engineering can be used to transform bacteria so they are able to make human . The figure shows how this is done. Proteins made by the bacteria are injected into people who cannot produce them because of .
::基因工程除了基因疗法外,还可用于改造细菌,使其能成为人类。图中显示了如何做到这一点。细菌制造的蛋白被注射到无法生产的人身上。Genetically Engineering Bacteria to Produce a Human Protein. Bacteria can be genetically engineered to produce a human protein, such as a cytokine. A cytokine is a small protein that helps fight infections.
::细菌可以进行基因改造,生产人体蛋白质,如细胞基素。细胞基素是一种小蛋白,有助于防治感染。Insulin was the first human protein to be produced in this way. Insulin helps cells take up glucose from the . People with type 1 diabetes have a mutation in the gene that normally codes for insulin. Without insulin, their blood glucose rises to harmfully high levels. At present, the only treatment for type 1 diabetes is the injection of insulin from outside sources. Until recently, there was no known way to make human insulin outside the . The problem was solved by gene cloning. The human insulin gene was cloned and used to transform bacterial cells, which could then produce large quantities of human insulin.
::胰岛素是第一个以这种方式生产的人类蛋白质。胰岛素帮助细胞从细胞中取出葡萄糖。1型糖尿病患者在通常为胰岛素编码的基因中发生突变。没有胰岛素,他们的血糖会上升至有害水平。目前,对1型糖尿病的唯一治疗是从外部注射胰岛素。直到最近,还没有已知的方法将人类胰岛素从外引入。问题通过基因克隆得到解决。人类胰岛素基因被克隆并用于改造细菌细胞,然后可以产生大量的人类胰岛素。Applications in Agriculture
::农业应用Genetic engineering has been used to create transgenic crops . Transgenic crops are genetically modified with new genes that code for traits useful to humans. The diagram shows how a transgenic crop is created.
::转基因作物经过转基因作物转基因作物的基因改造,新基因编码了对人类有用的特性,图表显示了转基因作物是如何创造的。Creating a Transgenic Crop. A transgenic crop is genetically modified to be more useful to humans. The bacterium transfers the T-DNA (from the Ti plasmid) fragment with the desired gene into the host plant's nuclear genome.
::创建转基因作物。转基因作物经过基因改造,对人类更有用。细菌将T-DNA碎片(从Tiplasmid)与所希望的基因转移至宿主工厂的核基因组。Transgenic crops have been created with a variety of different traits. They can yield more food, taste better, survive drought, tolerate salty soil , and resist insect pests, among other things. Scientists have even created a transgenic purple tomato (pictured ) that contains high levels of cancer-fighting compounds called antioxidants.
::转基因作物是用各种不同的特性创造的。 它们可以生产更多的食物、更好的口味、在干旱中生存、忍受咸土和抗虫害等。 科学家甚至创造了一种转基因紫番茄(图象 ) , 含有高含量的抗癌化合物,叫做抗氧化剂。Transgenic Purple Tomato. A purple tomato is genetically modified to contain high levels of antioxidants. A gene for the compound was transferred into normal red tomatoes.
::紫色番茄经过基因改造,含有高剂量抗氧化剂,该化合物的基因被转移到正常的红番茄中。Ethical, Legal, and Social Issues
::伦理、法律和社会问题The use of genetic engineering has raised a number of ethical, legal, and social issues. Here are just a few:
::基因工程的使用引起了一些伦理、法律和社会问题。-
Who owns genetically modified organisms (such as bacteria)? Can such organisms be patented like inventions?
::谁拥有转基因生物(如细菌)?这种生物能否像发明一样获得专利? -
Are genetically modified foods safe to eat? Might they have unknown harmful effects on the people who consume them?
::转基因食品是否安全? 它们是否会对食用它们的人产生未知的有害影响? -
Are genetically engineered crops safe for the environment? Might they harm other organisms — or even entire
?
::基因工程作物对环境是否安全? 它们是否会伤害其他生物 — — 甚至整个? -
Who controls a person’s genetic information? What safeguards ensure that the information is kept private?
::谁控制一个人的遗传信息?什么保障措施确保信息是保密的? -
How far should we go to ensure that children are free of mutations? Should a
be ended if the
fetus
has a mutation for a serious genetic disorder?
::我们应该走多远才能确保儿童免受突变影响? 如果胎儿发生严重基因紊乱的突变,我们应该结束吗?
This example shows how complex such issues may be:
::这个例子说明此类问题可能有多复杂:A strain of corn has been created with a gene that encodes a natural pesticide. On the positive side, the transgenic corn is not eaten by , so there is more corn for people to eat. The corn also doesn’t need to be sprayed with chemical pesticides, which can harm people and other living things. On the negative side, the transgenic corn has been shown to cross-pollinate nearby milkweed plants. Offspring of the cross-pollinated milkweed plants are now known to be toxic to monarch butterfly caterpillars that depend on them for food. Scientists are concerned that this may threaten the monarch , as well as other species that normally eat monarchs.
::玉米已经用一种基因将天然杀虫剂编码成。 从积极的一面看,转基因玉米没有被吃掉,因此人们可以吃更多的玉米。 玉米也不需要喷洒化学杀虫剂,因为化学杀虫剂会伤害人和其他生物。 在消极的一面,转基因玉米被证明横跨了附近的奶草植物。 交叉授乳草植物的分泌现在已知对依赖它们购买食物的君主蝴蝶毛虫有毒。 科学家担心这可能威胁到君主以及其他通常吃君主的物种。As this example shows, the pros of genetic engineering may be obvious, but the cons may not be known until it is too late, and the damage has already been done. Unforeseen harm may be done to people, other species, and entire ecosystems. No doubt the ethical, legal, and social issues raised by genetic engineering will be debated for decades to come.
::正如这个例子所显示的,遗传工程的利弊可能是显而易见的,但是,除非为时已晚,而且损害已经发生,否则这些弊端可能不会为人所知。 人类、其他物种和整个生态系统可能会遭受意外的伤害。 毫无疑问,遗传工程引起的伦理、法律和社会问题将在未来几十年里辩论。Feature: Reliable Sources
::特征:可靠来源Genetically modified foods (or GM foods) are foods produced from genetically modified organisms. These are organisms that have had changes introduced into their DNA using methods of genetic engineering . Commercial sale of GM foods began in 1994, with a tomato that had delayed ripening. By 2015, three major crops grown in the U.S. were raised mainly from GM seeds , including field corn, soybeans, and cotton. Many other crops were also raised from GM seeds, ranging from a variety of vegetables to sugar beets. Other sources of GM foods in our diet include meats, eggs , and dairy products from that have eaten GM feed, as well as a plethora of food products that contain some form of soy or corn products, such as soybean oil, soybean flour, corn oil, corn starch , and corn syrup. A quick glance at the ingredients list of most processed foods shows that these products are added to many of the items in a typical American diet.
::转基因食品(或转基因食品)是转基因生物生产的食品,这些有机体已经采用基因工程方法将基因改变转化为DNA。1994年开始商业销售转基因食品,番茄推迟成熟。到2015年,美国种植的三大主要作物主要来自转基因种子,包括田间玉米、大豆和棉花。其他许多作物也从转基因种子中种植,从蔬菜到甜菜。我们饮食中的转基因食品的其他来源包括肉类、鸡蛋和食用转基因饲料的奶制品,以及含有某种豆类或玉米制品(如豆油、豆类面、玉米油、玉米淀粉、玉米淀粉和玉米糖浆)的多种食品产品。快速查看大多数加工食品的成分清单表明,这些产品是典型美国饮食中的许多产品。Most scientists think that GM foods are not necessarily any riskier to human health than conventional foods. Nonetheless, in many countries, including the U.S., GM foods are given more rigorous evaluations than conventional foods. For example, GM foods are assessed for toxicity, ability to cause allergic reactions, and stability of inserted genes. GM crops are also evaluated for possible environmental effects, such as outcrossing, which is the of genes from GM plants to conventional crops or wild plant species.
::大多数科学家认为,与传统食品相比,转基因食品不一定对人类健康构成任何风险。 然而,在许多国家,包括美国,转基因食品比传统食品得到更严格的评估。 比如,转基因食品被评估为毒性、引起过敏反应的能力和插入基因的稳定性。 转基因作物也被评估为可能的环境影响,比如外向效应,即转基因植物基因到传统作物或野生植物物种的基因。Despite the extra measures used to evaluate GM foods, there is a lot of public concern about them, including whether they are safe for human health, how they are labeled, and their environmental impacts. These concerns are based on a number of factors, such as the worrying belief that scientists are creating entirely new species, and a perceived lack of benefits to the consumer of GM foods. People may also doubt the validity of risk assessments, especially with regard to long-term effects. Lack of labeling of GM foods is also an issue because it denies consumers the choice of buying GM or conventional foods.
::尽管采取了额外措施来评估全球机制的食品,但公众仍然非常关注这些食品,包括这些食品是否对人类健康安全、标签如何以及对环境的影响。 这些担忧基于若干因素,例如令人担忧的科学家正在创造全新的物种,以及人们认为对全球机制食品的消费者缺乏好处。 人们还可能怀疑风险评估的有效性,特别是在长期影响方面。 缺乏全球机制食品标签也是一个问题,因为它剥夺了消费者购买全球机制食品或常规食品的选择权。Find reliable online sources about GM foods. Look for information to answer the questions below. Make sure you evaluate the nature of the sources when you assess the reliability of the information they provide. Consider whether the sources may have a vested interest in one side of the issue or another. For example, major chemical companies might promote the use of seeds for crops that have been genetically engineered to be herbicide tolerant. Why? Because it boosts the use of the weed-killing chemical herbicides they produce and sell.
::寻找可靠的关于 GM 食品的在线来源。 寻找信息以回答下面的问题 。 在评估所提供信息的可靠性时, 请确定您评估来源的性质 。 考虑来源是否在问题的一方或另一方具有既得利益 。 例如, 主要化学公司可能会提倡将种子用于基因改造后能耐用除草剂的作物 。 为什么? 因为它会促进使用它们生产和销售的除草剂的除草剂。-
In what ways are crops modified genetically? What traits are introduced, and what methods are used to introduce them?
::以什么方式改变作物的基因?采用什么特性,采用什么方法来引进这些特性? -
What are the main human safety questions about GM foods? How is the human safety of GM foods assessed?
::有关转基因食品的主要人类安全问题是什么?如何评估转基因食品的人类安全? -
What are the main environmental concerns about GM crops? How is risk assessment for the environment performed?
::全球机制作物的主要环境问题是什么?如何对环境进行风险评估? -
What are the major pros and
cons of GM crops and foods? Who is most affected by these pros and cons? For example, for pros, do growers and marketeers receive most of the benefits, or do consumers also reap rewards?
::转基因作物和粮食的主要利弊是什么? 谁受这些利弊的影响最大?例如,对利弊来说,种植者和市场主是获得大部分好处,还是消费者也获得回报?
Summary
::摘要-
Genetic engineering is the use of technology to change the genetic makeup of living things for human purposes.
::遗传工程是利用技术改变人类生物的遗传构成。 -
Genetic engineering methods include gene cloning and the polymerase chain reaction. Gene cloning is the process of isolating and making copies of a DNA segment, such as a gene. The polymerase chain reaction makes many copies of a gene or other DNA segment.
::遗传工程方法包括基因克隆和聚合酶链反应,基因克隆是分离和复制基因等DNA部分的过程,聚合酶链反应产生许多基因或其他DNA部分的复制品。 -
Genetic engineering can be used to transform bacteria so they are able to make human proteins, such as insulin. It can also be used to create transgenic crops,
like
crops that yield more food or resist insect pests.
::遗传工程可以用来改造细菌,以便它们能够制造人类蛋白质,如胰岛素,也可以用来制造转基因作物,如产生更多食物或抗虫害的作物。 -
Genetic engineering has raised a number of ethical, legal, and social issues. For example, are genetically modified foods safe to eat? Who controls a person’s genetic information?
::基因工程引发了一系列伦理、法律和社会问题。 比如,转基因食品是否安全饮食? 谁控制一个人的基因信息?
Review
::回顾1. Define genetic engineering
::1. 界定遗传工程2. What is recombinant DNA?
::2. 什么是重组DNA?3. Identify the steps of gene cloning.
::3. 确定基因克隆的步骤。4. What is the purpose of the polymerase chain reaction?
::4. 聚合酶链反应的目的何在?5. Make a flow chart outlining the steps involved in creating a transgenic crop.
::5. 绘制一个流程图,概述创造转基因作物的步骤。6. Explain how bacteria can be genetically engineered to produce a human protein.
::6. 解释如何对细菌进行基因改造,以生产人类蛋白质。7. Identify an ethical, legal, or social issue raised by genetic engineering . State your view on the issue, and develop a logical argument to support your view.
::7. 查明遗传工程引起的伦理、法律或社会问题,陈述你对这个问题的看法,并发展合乎逻辑的论据来支持你的看法。8. Explain what primers are and what they do in PCR.
::8. 解释开源器是什么以及它们在PCR中做什么。9. True or False: Transgenic crops can be created using recombinant DNA.
::9. 真实或假:可使用重组DNA来创造转基因作物。10 . True or False: Gene cloning is defined as the creation of an identical copy of an entire organism.
::10. 真实或假:基因克隆的定义是创造整个生物体的相同副本。11. The enzyme Taq polymerase was originally identified from bacteria that live in very hot environments, such as hot springs. Why does this fact make Taq polymerase particularly useful in PCR reactions?
::11. 酶Taq聚合酶最初是从生活在温泉等极热环境中的细菌中发现的,为什么这一事实使得Taq聚合酶在PCR反应中特别有用?12. A circular piece of DNA from bacteria that is often used to create recombinant DNA is called a _________ .
::12. 细菌的循环DNA通常用于产生重组DNA,称为。13. Which of the following is a possible use for genetic engineering , now or in the future?
::13. 以下哪些是现在或将来基因工程的可能用途?a. curing genetic disorders
::a. 治疗遗传疾病b. creating transgenic crops that are resistant to pests
::b. 创造抗虫害的转基因作物c. producing human proteins in non-human cells
::c. 在非人体细胞中产生人类蛋白质d. all of the above
::d. 以上所有情况13. Bacteria that contain a recombinant plasmid are said to be...
::13. 据说,含有再组合质谱的细菌是...a. transformed
::a. 转变b. translated
::b. 翻译c. transcripted
::c. 抄录d. a transgenic crop
::d. 转基因作物Explore More
::探索更多Learn more about genetic engineering and how it can be applied to science here:
::学习更多有关遗传工程的知识,Check out this video describing the use of genetically modified products in the home:
::这段影片描述家庭使用转基因产品的情况: -
In the
isolation
step, an
is used to break
at a specific base sequence. This is done to isolate a gene.
