1、Foundations of Genetics（遗传学的建立）,Allele:等位基因alternative forms of a gene for a particular characteristic (e.g. attached earlobe(耳垂) genes and free earlobe genes are alternative alleles for ear shape)nonallelic genes:非等位基因,dihybrid cross: 双因子杂种杂交AaBb*AaBbtest cross：测交 F1*aa 确定F1是纯合子还是杂合子a cross between
2、 a heterozygote(异质结合体) of unknown genotype and an individual homozygous(同型的) for the recessive genes in question,Dominant:显性的 dominance the member of a pair of alleles that shows its effect in the phenotype whatever other allele is present.recessive:隐性的 recessiveness the member of a pair of alleles
3、that does not shows its effect in the presence of any other allelic partner.,Genotype:基因型the catalog of genes of an organism, whether or not these genes are expressed.Karyotype:核型，染色体组型phenotype:表现型the physical, chemical, and psychological 心理的expression of genes possessed by an organism.,Germ(种子,胚)
4、plasm theory:种质学说a substance thought to be transmitted in the gametes配子(germ cells) in an unchanged form from generation to generation. The germ plasm was believed to be unaffected by the environment and to give rise to the body cells.,种质学说：德国生物学家A.魏斯曼1892年提出的有关遗传物质的学说，认为多细胞的生物体可截然地区分为种质和体质两部分。种质是亲代
5、传递给后代的遗传物质，存留在生殖细胞的染色体上,种质可以发育为新个体的体质,但有一部分仍保持原来的状态作为后代发育的基础，体质可以通过生长和发育而形成为新个体的各个组织和器官，但它不能产生种质。体质受环境影响而获得的变异性状也不能遗传给后代。体质随个体死亡而消失；只有种质才能世代传递，连续不绝。所以这一学说又称为种质连续学说。为后来T.H.摩尔根开创的细胞遗传学和对遗传物质的深入探索奠定了理论基础。,Homozygous:纯合的a diploid organism that has two identical alleles for particular characteristicheter
6、ozygous:杂合的a diploid organism that has two different allelic forms of a particular gene.,Incomplete dominance:不完全显性the condition in which two allelic genes have a different effect when they are together as a heterozygote in a diploid cell than either of them have in the homozygous state.Codominance:
7、共显性杂合体中一对等位基因的作用都表现,Law of independent assortment:独立分配定律members of one gene pair will separate from each other independently of the members of other gene pairs.,Law of segregation:分离定律 when gametes are formed by a diploid organism, the alleles that control a trait(特征) separate from one another into
8、different gametes, retaining their individuality(个性,个体状态),Nondisjunction:不分离the failure of separation of paired chromosomes at metaphase, resulting in one daughter receiving both and the other daughter cell none of the chromosomes in question. Nondisjunction can occur during a meiotic or mitotic div
9、ision.,Pangenesis:泛生论，泛生说the theory of heredity postulating(假设) that germs, humours(体液), or essences migrate from individual body cells to the sex organs and contribute to the gametes.,Punnett square:庞纳特方格a method used to determine the probabilities of combination in a zygote(受精卵),Text1. early theor
10、ies of inheritanceearly ideas of inheritance included Hippocrates theory of pangenesis and August Weismanns germ plasm theory. 遗传学的早期理论包括Hippocrates的泛生说和A.Weismann的种质学说。,希波克拉底(希腊文 英文Hippocrates of Cos II 或者 Hippokrates of Kos，约前460前377)被西方尊为“医学之父”的古希腊著名医生，欧洲医学奠基人，古希腊医师，西方医学奠基人。提出“体液(humours)学说”，认为人体
11、由血液(blood)、粘液(phlegm)、黄胆(yellow bile)和黑胆(black bile)四种体液组成，这四种体液的不同配合使人们有不同的体质。他把疾病看作是发展着的现象，认为医师所应医治的不仅是病而是病人；从而改变了当时医学中以巫术和宗教为根据的观念。主张在治疗上注意病人的个性特征、环境因素和生活方式对患病的影响。重视卫生饮食疗法，但也不忽视药物治疗，尤其注意对症治疗和预后。他对骨骼、关节、肌肉等都很有研究。他的医学观点对以后西方医学的发展有巨大影响。,August Weismann，(18341914)德国动物学家 。1834 年1月17日生于法兰克福 ，1914年11月5日
12、卒于弗赖堡 。1856年入格丁根大学学医 。先后在巴登和奥地利当过军医和私人开业医生。1861年在吉森大学从师于德国动物学家K.G.洛伊卡尔特，学习动物发生学及形态学，1863年完成了关于双翅目昆虫变态的论文。1866年担任弗赖堡大学医学系动物学和比较解剖学副教授，1868年在该校创办动物研究所，任第一任所长，1871年升任教授。60年代中期以后因眼疾不得不终止显微镜下的研究而转向遗传、发生和进化问题的理论探讨。他讲授达尔文进化论多年 ，直至1912年退休。,Based on experiments with mice, Weismann proposed that hereditary in
13、formation in gametes transmitted traits to progeny.基于小鼠实验，维丝曼提出遗传信息储存在配子中并将遗传信息传递给后代。,Both of these views incorporated the blending theory: they held that heritable traits of the two parents blend, so that the distinct characteristics of each are lost in offspring.这两个早期观点合起来形成融合理论：子代拥有父母本混合的遗传特征，而不完
14、全象亲代。,2. Gregor Mendel and the birth of GeneticsGregor Mendel, an Augustinian monk in the monastery at Brunn, Austria, is known as the “father of genetics”.孟德尔（公元1822公元1884 ），一名奥地利修道士，众所周知的遗传学之父,Having been exposed to theories of the particulate nature of matter while a university student and having
15、 a background in mathematics, Mendel carried out a series of carefully planned experiments that demonstrated the particulate nature of heredity. 当他还是大学生时就提出了物质的粒子属性理论，同时他学习数学。孟德尔进行了一系列周密安排的实验来证实遗传的颗粒性。,His revolutionary ideas were neither understood nor accepted until many years after Mendel died.直到
16、他去世后，他的创新性理论才被理解和接受。,孟德尔于1822年出生在海因珍多弗镇，1843年他进入奥地利布鲁恩一家奥古斯都修道院。1847年他被任命为牧师。从1851年到1853年在维也纳大学学习数学和自然科学。从1854年到1868年在布鲁恩现代学校担任自然科学代课教师。与此同时，孟德尔从1856年起开始进行他的著名的植物育种实验。1865年他推导出了著名的遗传学定律，他将定律用一篇论文表述出来，并将论文呈交给布鲁恩自然历史学会。1866年他的成果被发表在该学会学报上，题目是“植物杂交实验”。三年后又在同一杂志上发表了第二篇论文。1868年孟德尔被任命为牧师会会长，专职行政事务。1900年，孟
17、德尔的研究成果被发现。,3.Mendels classic experimentsMendel studied genetics through plant-breeding experiments with the garden pea, a plant species that is self-fertilizing(施肥、使受精) and breeds true(each offspring is identical to the parent in the trait of interest利益利害).孟德尔通过豌豆实验研究遗传学，豌豆是自花授粉植物和纯品系。,Breed true(t
18、o type):生出后代酷似其双亲breed in and in: 近亲交配繁殖breed out and out: (动物的)异种繁殖breed out:在人工繁殖过程中消除(品种的特性)breed up:养育，教育，养成,To test the blending theory, he focused his research on seven distinct characters. Each of these characters, such as seed color and plant height, present only two, clear-cut possibilities
19、.为验证融合理论，他的研究主要集中在7个明显特征上。例如，种子颜色，植株高度，这些特征只有两个明确的可能性。,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.他记录了每一对父母本豌豆产生的所有子代类型和数量，以及再杂交产生子2代的结果。,For each of the characters he studied, Mendel fo
20、und that one trait was dominant while the other was recessive. In the second filial子女的(F2) generation, the ration of dominant to recessive was 3:1.孟德尔发现对于每个特征而言，要么显性，要么隐性。在F2代中显性与隐性比为31。,Mendel deduced that this result was possible only if each individual possesses only two hereditary units, one fro
21、m each parent. The units Mendel hypothesized are today known as alleles, alternative forms of genes.孟德尔推论只有在每个个体仅拥有两个研究遗传单元，并且每个单元来自一个亲代时，实验结果才成立。此遗传单元就是今天共识的等位基因。,Genes are the basic units of heredity. An organism that inherits identical alleles for a trait from each parent is said to be homozygous
22、 for that trait; if different alleles for a trait are inherited, the organism is heterozygous for that trait.基因是遗传的基本单元，两个一样的等位基因决定一个特征，称纯合;相反，称杂合。,When an organism is heterozygous for a trait, the resulting phenotype for that trait expresses only the dominant allele.当生物是杂合时，它的表型由显性基因决定。,Thus, the o
23、rganisms phenotype its physical appearance and properties differs from its genotype, which may include both a dominant and a recessive allele因此，生物的表型(物理外表和属性)与基因型是不同的，其可同时含有一个显性基因和一个隐性基因。,A pictorial(形象化的生动的) representation表现 of all possible combinations of a genetic cross is known as a Punnett squa
24、re.旁纳特方格可以陈列所有可能的遗传组合。,The results of Mendels experiments on dominant and recessive inheritance led to Mendel s first law: the law of segregation. 孟德尔关于显性和隐性遗传的实验结果导致了孟德尔第一定律-分离定律的产生。,This law states that for a given trait an organism inherits one allele from each parent.这个定律说的是生物只遗传父母本等位基因对的一个等位基因。
25、,Together these alleles form the allele pair. When gametes are formed during meiosis, the two alleles become separated(halving of chromosome number).这些基因一起形成基因对。减数分裂期形成配子时两个等位基因分离。,To gain evidence for his theory Mendel performed test crosses, mating(使配对使交配) plants of unknown genotype to plants that
26、 were homozygous recessive for the trait of interest.为验证此理论，他做了测交实验，即基因型未知的植物与纯合的隐性基因植物杂交。,The ratio of dominant phenotype(if any) in the progeny makes clear whether the unknown genotype is heterozygous, homozygous dominant, or homozygous recessive.通过子代中显性表型的比率可以明确测得未知基因型是杂合的或纯合显性的或者纯隐性的。,4. Mendels
27、 ideas and the law of independent assortmentMendel also performed dihybrid cross, which enabled him to consider how traits are inherited relative to one another.孟德尔还进行了双因子杂合子杂交试验，这个实验使他仔细考虑两个特征是如何相互影响遗传的。,This work led to the law of independent assortment, which states that the alleles of genes gove
28、rning different characters are inherited independently.试验结果产生独立分配定律，即控制不同特征的等位基因独立遗传。,An apparent exception to Mendels laws is incomplete dominance, a phenomenon in which offspring of a cross exhibit a phenotype that is intermediate中间的 between those of the parents.特例是不完全显性。子代的表型是父母本的中间类型。,Mendel pre
29、sented his ideas in 1866 in a scientific paper published by the Brunn Society for Natural History. 1866年，孟德尔在由布鲁恩自然历史学会出版的期刊上发表了他的科学论文，陈诉了他的观点。,Unfortunately, the meaning of his research was not understood by other scientists of the day.His work was rediscovered in 1900 by Carl Correns and Hugo de V
30、ries.不幸的是，他的研究不被当时科学家理解在1900年，他的著作被发现利用。,荷兰Dutch ：Hugo de Vries德国German：Carl Erich Correns 奥地利Austrian：Erich von Tschermak -Sevsenegg,5. Chromosomes and Mendelian GeneticsSoon after Mendels work was rediscovered, Walter Sutton and Theodor Boveri independently proposed that the hereditary units might
31、 be located on chromosomes.孟德尔著作被再发现不久，Walter Sutton 和Theodor Boveri各自独立提出，遗传单位可能定位在染色体组上。,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. Thomas Hunt Morgan和他的学生在哥伦比亚大学进行了验证这个假设的实
32、验，他们的研究对象是果蝇的性染色体。,Morgans studies were also the first exploration of sex-linked traits. Morgan的论文第一次探索了伴性遗传现象。,It also led to the discovery in 1916 by Calvin Bridges of the phenomenon of nondisjunction, in which a chromosome pair fails to segregate during meiosis.导致了1916年Calvin Bridges发现不分离现象，即在减数分裂中，染色体对不分离。,
