1、2023-5-191Lesson fourFoundation of genetics遗传学的基础遗传学的基础2023-5-1921.Early theories of inheritance遗传学的早期理论遗传学的早期理论 Early ideas of inheritance included Hippocrates theory of pangenesis pndenisis and August Weismanns vaism:n .遗传学的早期理论包括希波克拉底（古希腊名医）遗传学的早期理论包括希波克拉底（古希腊名医）的泛生说和奥古斯特的泛生说和奥古斯特-魏斯曼魏斯曼(德国生物学家德国
2、生物学家)的种质的种质理论。理论。2023-5-193Based on experiments with mice,Weismann proposed that hereditary information in gametes mtz transmitted traits to progeny prdini.基于小鼠实验，魏斯曼提出配子中的遗传信息可以将遗基于小鼠实验，魏斯曼提出配子中的遗传信息可以将遗传特性传递给后代。传特性传递给后代。2023-5-194 Both of these early views incorporated ink:preitid the blending ble
3、ndi theory:they held that heritableheritbl traits of the two parents blend,so that the distinct characteristics krktristik of each are lost in offspring.这两个早期观点组合起来形成混合理论：两个亲本的遗这两个早期观点组合起来形成混合理论：两个亲本的遗传特征混合传特征混合,那么每个亲本的不同特征就在子代中丧失那么每个亲本的不同特征就在子代中丧失了了.2023-5-195The Mendel Theory-the most popular oneT
4、he Mendel Theory is,by far,the best known and universally accepted theory on genetics and inheritance.The theory deals with known factors and with a single trait and the manner in which these qualities are transmitted.What other theories of inheritance and genetics do you know?2023-5-1962.Gregor Men
5、del and the Birth of Genetics格里戈格里戈-孟德尔和遗传学的诞生孟德尔和遗传学的诞生2023-5-197Gregor Mendel,an Augustinian:gstinin monk mk in the monastery mnstri at Brunn,Austria,is known as the“father of genetics”.格里戈格里戈-孟德尔，是奥地利布鲁恩的修道院的一名奥古孟德尔，是奥地利布鲁恩的修道院的一名奥古斯丁修道士斯丁修道士,是众所周知的遗传学之父。是众所周知的遗传学之父。2023-5-198Having been exposed
6、to theories of the particular nature of matter while a university student and having a background in mathematics,Mendel carried out a series of carefully planned experiments that demonstrated the particulate ptikjulit nature of heredity hrediti.孟德尔曾在读大学时学习（接触）了物质的粒子属性孟德尔曾在读大学时学习（接触）了物质的粒子属性,并且，孟德尔有数
7、学基础，于是，他进行了一系列周并且，孟德尔有数学基础，于是，他进行了一系列周密安排的实验来证实遗传的颗粒属性。密安排的实验来证实遗传的颗粒属性。2023-5-199His revolutionary ideas were neither understood nor accepted until many years after Mendel died.直到他去世后若干年，他的创新性的理论才被理解和接直到他去世后若干年，他的创新性的理论才被理解和接受。受。2023-5-19103.Mendels Classic Experiments孟德尔的经典实验孟德尔的经典实验2023-5-1911Men
8、del studied genetics through plant-breeding experiments with the garden pea,a plant that is self-fertilizing and breeds bri:d true(each offspring is identical to the parent in the trait of interest).孟德尔通过豌豆育种实验来研究遗传学，豌豆是自花授孟德尔通过豌豆育种实验来研究遗传学，豌豆是自花授粉的粉的,并且是真实遗传的并且是真实遗传的(每个子代和亲本的遗传特征是每个子代和亲本的遗传特征是一样的一样
9、的)。2023-5-1912To test the blending theory,he focused his research on seven distinct characters.为验证混合理论，他的研究主要集中在为验证混合理论，他的研究主要集中在7个不同的特征个不同的特征上。上。2023-5-1913Each of these characters,such as seed color and plant height,present only two,clear-cut possibilities.每个特征如种子颜色，植株高度等，都只有两个明确的可每个特征如种子颜色，植株高度等，
10、都只有两个明确的可能性。能性。He also recorded the type and number of all progeny produced from each pair of parent pea plants,and followed the results of each cross for two generations.他也记录了来自于每一对亲本的所有子代的类型和数量，他也记录了来自于每一对亲本的所有子代的类型和数量，和两个子代杂交的结果。和两个子代杂交的结果。2023-5-1914 For each of the characters he studied,Mendel
11、found that one trait was dominant dminnt while the other was recessive risesiv.对于他研究的每个特征而言，孟德尔发现一个特征是显性对于他研究的每个特征而言，孟德尔发现一个特征是显性的的,那么另一个就是隐性的。那么另一个就是隐性的。In the second filial filjl (F2)generation,the ratio of dominant to recessive was 3:1.在子在子2代中代中,显性与隐性比为显性与隐性比为3 1。2023-5-1915Mendel deduced that th
12、is results was possible only if each individual possesses only two hereditary units,one from each parent.孟德尔推论孟德尔推论:只有在每个个体仅拥有两个遗传单元，并每只有在每个个体仅拥有两个遗传单元，并每个单元来自一个亲本时，实验结果才成立。个单元来自一个亲本时，实验结果才成立。2023-5-1916The units Mendel hypothesized haipisaiz are today known as alleles li:l,alternative forms of gene
13、s.孟德尔假设的遗传单元就是今天共识的等位基因孟德尔假设的遗传单元就是今天共识的等位基因,基因的基因的两种形式。两种形式。Genes are the basic units of heredity.基因是遗传的基本单元基因是遗传的基本单元.2023-5-1917An organism that inherits identical alleles for a trait from each parent is said to be homozygous hmzaigs for that trait;if different alleles for a trait are inherited,t
14、he organism is heterozygous hetruzaigs for that trait.从亲本遗传而来的是一个特征的两个相同的等位基因的从亲本遗传而来的是一个特征的两个相同的等位基因的个体被认为是纯合的。反之个体被认为是纯合的。反之,遗传而来的是两个不同的等遗传而来的是两个不同的等位基因的个体，就是杂合的。位基因的个体，就是杂合的。2023-5-1918 When an organism is heterozygous for a trait,the resulting phenotype for that trait expresses only the dominant
15、 allele.对某一个特征而言对某一个特征而言,当个体是杂合时，它的表型仅由显性基因决定当个体是杂合时，它的表型仅由显性基因决定。Thus,the organisms phenotype fi:ntaip its physical appearance and propertiesdiffers from its genotype dentaip,which may include both a dominant and a recessive allele.因此，生物的表型与基因型是不同的因此，生物的表型与基因型是不同的,表型是个体的物理特征和品质表型是个体的物理特征和品质,而基因型包括一
16、个显性基因和一个隐性基因。而基因型包括一个显性基因和一个隐性基因。2023-5-1919 A pictorial representation of all possible combination of a genetic cross is known as a Punnett square.遗传杂交的所有可能的组合图表被称为旁纳特方格。遗传杂交的所有可能的组合图表被称为旁纳特方格。Punnett square：a method used to determine the probabilities of combination in a zygote zaigut.2023-5-1920T
17、he results of Mendels experiments on dominant and recessive inheritance led to Mendels first law:the law of segregation.基于显性和隐性遗传的实验结果基于显性和隐性遗传的实验结果,孟德尔提出孟德尔提出了分离定律分离定律。2023-5-1921This law states that for a given trait an organism inherits one allele from each parent.该定律认为该定律认为:对一个给定的特征而言对一个给定的特征而言,
18、个体从每个亲本获个体从每个亲本获得一个等位基因。得一个等位基因。Together these alleles form the allele pair.这些等位基因一起形成等位基因对。这些等位基因一起形成等位基因对。2023-5-1922 When gametes gmi:t are formed during meiosis,the two alleles become separated(halving of chromosome number).减数分裂期形成配子时两个等位基因分离减数分裂期形成配子时两个等位基因分离(染色体数目的减半染色体数目的减半)。2023-5-1923Test c
19、ross：a cross between a heterozygote of unknown genotype and an individual homozygous for the recessive genes in question.To gain evidence for his theory Mendel performed test crosses,mating plants of unknown genotype to plants that were homozygous hmzaigus recessive risesiv for the trait of interest
20、.为验证此理论，他做了测交实验，即基因型未知的植物个体与纯为验证此理论，他做了测交实验，即基因型未知的植物个体与纯合隐性的个体杂交。合隐性的个体杂交。2023-5-1924The ratio of dominant phenotypes(if any)in the progeny makes clear whether the unknown genotype is heterozygous hetruzaigs,homozygous dominant,or homozygous recessive.子代显性表型的比例可以明确测得该未知基因型是杂合子代显性表型的比例可以明确测得该未知基因型是杂
21、合的的,纯合显性的纯合显性的,还是纯合隐性的。还是纯合隐性的。2023-5-19254.Mendels ideas and the law of independent assortment2023-5-1926 Mendel also performed dihybrid daihaibrid crosses,which enabled him to consider how two traits are inherited relative to one another.孟德尔也进行了双因子杂交试验，该实验说明了两个特征孟德尔也进行了双因子杂交试验，该实验说明了两个特征相互间是如何遗传的。
22、相互间是如何遗传的。2023-5-1927This work led to the law of independent assortment,which states that the alleles of genes governing different characters are inherited independently.试验结果产生了自由组合定律，即控制不同性状的等位基试验结果产生了自由组合定律，即控制不同性状的等位基因是独立遗传的。因是独立遗传的。2023-5-1928An apparent exception to Mendels law is incomplete do
23、minance,a phenomenon in which offspring of a cross exhibit a phenotype that is intermediate between those of the parents.孟德尔定律的一个特例是，不完全显性，即杂交后子代的孟德尔定律的一个特例是，不完全显性，即杂交后子代的表型是父母亲本的中间类型。表型是父母亲本的中间类型。2023-5-1929However,incomplete dominance reflects the fact that both alleles for the trait in question e
24、xert an effect on the phenotype.但是，不完全显性说明了两个等位基因可能对表型有影响但是，不完全显性说明了两个等位基因可能对表型有影响。The alleles themselves remain separate.等位基因本身仍然是分离的。等位基因本身仍然是分离的。2023-5-1930 Mendel presented his ideas in 1866 in a scientific paper published by the Brunn Society for Natural History.1866年，孟德尔将其想法发表在由布鲁恩自然历史学会出版的科学年
25、，孟德尔将其想法发表在由布鲁恩自然历史学会出版的科学论文上。论文上。Unfortunately,the meaning of his research was not understood by other scientists of the day.不幸运的是，他的研究没被当时科学家所接受。不幸运的是，他的研究没被当时科学家所接受。His work was rediscovered in 1900 by Carl Correns and Hugo de Vries.在在1900年，他的著作再次被年，他的著作再次被Carl Correns and Hugo de Vries（科（科伦斯和德弗里
26、斯）发现。伦斯和德弗里斯）发现。2023-5-19315.Chromosomes and Mendelian Genetics2023-5-1932Soon after Mendels work was rediscovered,Walter Sutton and Theodor Boveri independently proposed that the hereditary units might be located on chromosomes.孟德尔著作再次被发现不久，孟德尔著作再次被发现不久，Walter Sutton 和和Theodor Boveri（萨顿和鲍维里）提出，遗传单位
27、可能定位在染色体上。（萨顿和鲍维里）提出，遗传单位可能定位在染色体上。Experiments to prove this hypothesis were carried out by Thomas Hunt Morgan and his students at Columbia University,in research on the sex chromosomes of fruit flies.哥伦比亚大学的哥伦比亚大学的Thomas Hunt Morgan（摩尔根）（摩尔根）和他的学生和他的学生进行的果蝇伴性遗传的研究证明了这一观点。进行的果蝇伴性遗传的研究证明了这一观点。2023-5-
28、1933Morgons studies were also the first exploration of sex-linked traits.同时，同时，Morgan也是研究伴性性状的第一位科学家。也是研究伴性性状的第一位科学家。It also led to the discovery in 1916 by Calvin Bridges of the phenomenon of nondisjunction nndisdnkn,in which a chromosome pair fails to segregate during meiosis.1916年，伴性遗传也导致了年，伴性遗传也
29、导致了Calvin Bridges（C.布里奇斯）的不布里奇斯）的不分离现象的发现，即在减数分裂中，染色体对不分离。分离现象的发现，即在减数分裂中，染色体对不分离。2023-5-1934pangenesis pndenisis泛生说泛生说gametes mtzcharacteristics krktristikprogeny prdinidominant dminntrecessive risesiv.filial filjlexert英英gz:talleles li:lhomozygous hmzaigsheterozygous hetruzaigsphenotype fi:ntaipgen
30、otype dentaipgametes gmi:tdihybrid daihaibrid2023-5-1937Chemical Abstract Servicewww.cas.org2023-5-1938化学文摘服务社化学文摘服务社CAS（Chemical Abstract Service）美国化学学会（）美国化学学会（ACS）旗下所出版的）旗下所出版的Chemical Abstract化学文摘的在线版数据库化学文摘的在线版数据库.“化学文摘化学文摘”是化学和生命科学研究领域是化学和生命科学研究领域中不可或缺的参考和研究工具，也是资料中不可或缺的参考和研究工具，也是资料量最大，最具权威的出版
31、物量最大，最具权威的出版物。About CAS2023-5-19392023-5-1940The CAS Source Index(CASSI)Search Tool is another free online resource intended to support researchers and librarians who need accurate bibliographic information.Use this free tool to quickly identify or confirm journal titles and abbreviations for public
32、ations indexed by CAS since 1907,including serial and non-serial scientific and technical publications.2023-5-1941SciFinder is a research discovery tool,suitable for both professional searchers and research scientists.You do not have to be an expert searcher to use SciFinder.Many organizations aroun
33、d the world use SciFinder to give their scientists direct access to CAS databases.SciFinder offers a one-stop shop experience with flexible search and discover options based on user input and workflow.You can search for substances,reactions,and patent and journal references anytime,anywhere.2023-5-19422023-5-19432023-5-19442023-5-19452023-5-19462023-5-1947是被引用次数最多的综合学科文献之一，周刊。它是美国科学院的院刊，亦是公认的世界四大名刊之一。美国国家科学院院刊（PNAS）由美国国家科学院创建于1914年，每周出版一次，是目前世界上引用率最高的科学期刊之一。Proceedings of the National Academy of Sciences2023-5-19482023-5-19492023-5-19502023-5-19512023-5-19522023-5-1953
