lesson-four-foundations-of-geneticsPPT演示課件

1、1,Foundations of Genetics（遺傳學的建立,2,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,3,dihybrid cross: 雙因子雜種雜交AaBb*AaBbtest cross：測交 F1*aa 確定F1是純合子還是雜合子a cross be

2、tween a heterozygote(異質(zhì)結合體) of unknown genotype and an individual homozygous(同型的) for the recessive genes in question,4,Dominant:顯性的 dominance the member of a pair of alleles that shows its effect in the phenotype whatever other allele is present.recessive:隱性的 recessiveness the member of a pair of a

3、lleles that does not shows its effect in the presence of any other allelic partner,5,Genotype:基因型the catalog of genes of an organism, whether or not these genes are expressed.Karyotype:核型，染色體組型phenotype:表現(xiàn)型the physical, chemical, and psychological 心理的expression of genes possessed by an organism,6,Ge

4、rm(種子,胚) plasm theory:種質(zhì)學說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,7,種質(zhì)學說：德國生物學家A.魏斯曼1892年提出的有關遺傳物質(zhì)的學說，認為多細胞的生物體可截然地區(qū)分為種質(zhì)和體

5、質(zhì)兩部分。種質(zhì)是親代傳遞給后代的遺傳物質(zhì)，存留在生殖細胞的染色體上,種質(zhì)可以發(fā)育為新個體的體質(zhì),但有一部分仍保持原來的狀態(tài)作為后代發(fā)育的基礎，體質(zhì)可以通過生長和發(fā)育而形成為新個體的各個組織和器官，但它不能產(chǎn)生種質(zhì)。體質(zhì)受環(huán)境影響而獲得的變異性狀也不能遺傳給后代。體質(zhì)隨個體死亡而消失；只有種質(zhì)才能世代傳遞，連續(xù)不絕。所以這一學說又稱為種質(zhì)連續(xù)學說。為后來T.H.摩爾根開創(chuàng)的細胞遺傳學和對遺傳物質(zhì)的深入探索奠定了理論基礎,8,Homozygous:純合的a diploid organism that has two identical alleles for particular characte

6、risticheterozygous:雜合的a diploid organism that has two different allelic forms of a particular gene,9,Incomplete dominance:不完全顯性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.

7、Codominance:共顯性雜合體中一對等位基因的作用都表現(xiàn),10,Law of independent assortment:獨立分配定律members of one gene pair will separate from each other independently of the members of other gene pairs,11,Law of segregation:分離定律 when gametes are formed by a diploid organism, the alleles that control a trait(特征) separate from

8、one another into different gametes, retaining their individuality(個性,個體狀態(tài),12,Nondisjunction:不分離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 mei

9、otic or mitotic division,13,Pangenesis:泛生論，泛生說the theory of heredity postulating(假設) that germs, humours(體液), or essences migrate from individual body cells to the sex organs and contribute to the gametes,14,Punnett square:龐納特方格a method used to determine the probabilities of combination in a zygote(

10、受精卵,15,Text1. early theories of inheritanceearly ideas of inheritance included Hippocrates theory of pangenesis and August Weismanns germ plasm theory. 遺傳學的早期理論包括Hippocrates的泛生說和A.Weismann的種質(zhì)學說,16,希波克拉底(希臘文 英文Hippocrates of Cos II 或者 Hippokrates of Kos，約前460前377)被西方尊為“醫(yī)學之父”的古希臘著名醫(yī)生，歐洲醫(yī)學奠基人，古希臘醫(yī)師，西方醫(yī)

11、學奠基人。提出“體液(humours)學說”，認為人體由血液(blood)、粘液(phlegm)、黃膽(yellow bile)和黑膽(black bile)四種體液組成，這四種體液的不同配合使人們有不同的體質(zhì)。他把疾病看作是發(fā)展著的現(xiàn)象，認為醫(yī)師所應醫(yī)治的不僅是病而是病人；從而改變了當時醫(yī)學中以巫術和宗教為根據(jù)的觀念。主張在治療上注意病人的個性特征、環(huán)境因素和生活方式對患病的影響。重視衛(wèi)生飲食療法，但也不忽視藥物治療，尤其注意對癥治療和預后。他對骨骼、關節(jié)、肌肉等都很有研究。他的醫(yī)學觀點對以后西方醫(yī)學的發(fā)展有巨大影響,17,August Weismann，(18341914)德國動物學家 。

12、1834 年1月17日生于法蘭克福 ，1914年11月5日卒于弗賴堡 。1856年入格丁根大學學醫(yī) 。先后在巴登和奧地利當過軍醫(yī)和私人開業(yè)醫(yī)生。1861年在吉森大學從師于德國動物學家K.G.洛伊卡爾特，學習動物發(fā)生學及形態(tài)學，1863年完成了關于雙翅目昆蟲變態(tài)的論文。1866年擔任弗賴堡大學醫(yī)學系動物學和比較解剖學副教授，1868年在該校創(chuàng)辦動物研究所，任第一任所長，1871年升任教授。60年代中期以后因眼疾不得不終止顯微鏡下的研究而轉向遺傳、發(fā)生和進化問題的理論探討。他講授達爾文進化論多年 ，直至1912年退休,18,Based on experiments with mice, Weism

13、ann proposed that hereditary information in gametes transmitted traits to progeny.基于小鼠實驗，維絲曼提出遺傳信息儲存在配子中并將遺傳信息傳遞給后代,19,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.這兩

14、個早期觀點合起來形成融合理論：子代擁有父母本混合的遺傳特征，而不完全象親代,20,2. Gregor Mendel and the birth of GeneticsGregor Mendel, an Augustinian monk in the monastery at Brunn, Austria, is known as the “father of genetics”.孟德爾（公元1822公元1884 ），一名奧地利修道士，眾所周知的遺傳學之父,21,Having been exposed to theories of the particulate nature of matter

15、 while a university student and having a background in mathematics, Mendel carried out a series of carefully planned experiments that demonstrated the particulate nature of heredity. 當他還是大學生時就提出了物質(zhì)的粒子屬性理論，同時他學習數(shù)學。孟德爾進行了一系列周密安排的實驗來證實遺傳的顆粒性,22,His revolutionary ideas were neither understood nor accept

16、ed until many years after Mendel died.直到他去世后，他的創(chuàng)新性理論才被理解和接受,23,孟德爾于1822年出生在海因珍多弗鎮(zhèn)，1843年他進入奧地利布魯恩一家奧古斯都修道院。1847年他被任命為牧師。從1851年到1853年在維也納大學學習數(shù)學和自然科學。從1854年到1868年在布魯恩現(xiàn)代學校擔任自然科學代課教師。與此同時，孟德爾從1856年起開始進行他的著名的植物育種實驗。1865年他推導出了著名的遺傳學定律，他將定律用一篇論文表述出來，并將論文呈交給布魯恩自然歷史學會。1866年他的成果被發(fā)表在該學會學報上，題目是“植物雜交實驗”。三年后又在同一雜志

17、上發(fā)表了第二篇論文。1868年孟德爾被任命為牧師會會長，專職行政事務。1900年，孟德爾的研究成果被發(fā)現(xiàn),24,3.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

18、).孟德爾通過豌豆實驗研究遺傳學，豌豆是自花授粉植物和純品系,25,Breed true(to type):生出后代酷似其雙親breed in and in: 近親交配繁殖breed out and out: (動物的)異種繁殖breed out:在人工繁殖過程中消除(品種的特性)breed up:養(yǎng)育，教育，養(yǎng)成,26,To test the blending theory, he focused his research on seven distinct characters. Each of these characters, such as seed color and plant

19、height, present only two, clear-cut possibilities.為驗證融合理論，他的研究主要集中在7個明顯特征上。例如，種子顏色，植株高度，這些特征只有兩個明確的可能性,27,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.他記錄了每一對父母本豌豆產(chǎn)生的所有子代類型和數(shù)量，以及再雜交產(chǎn)生子2代的結

20、果,28,For each of the characters he studied, Mendel found 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.孟德爾發(fā)現(xiàn)對于每個特征而言，要么顯性，要么隱性。在F2代中顯性與隱性比為31,29,Mendel deduced that this result was possible only if each

21、individual possesses only two hereditary units, one from each parent. The units Mendel hypothesized are today known as alleles, alternative forms of genes.孟德爾推論只有在每個個體僅擁有兩個研究遺傳單元，并且每個單元來自一個親代時，實驗結果才成立。此遺傳單元就是今天共識的等位基因,30,Genes are the basic units of heredity. An organism that inherits identical alle

22、les for a trait from each parent is said to be homozygous for that trait; if different alleles for a trait are inherited, the organism is heterozygous for that trait.基因是遺傳的基本單元，兩個一樣的等位基因決定一個特征，稱純合;相反，稱雜合,31,When an organism is heterozygous for a trait, the resulting phenotype for that trait expresse

23、s only the dominant allele.當生物是雜合時，它的表型由顯性基因決定,32,Thus, the organisms 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(物理外表和屬性)與基因型是不同的，其可同時含有一個顯性基因和一個隱性基因,33,A pictorial(形象化的生動的) representation表現(xiàn) of all poss

24、ible combinations of a genetic cross is known as a Punnett square.旁納特方格可以陳列所有可能的遺傳組合,34,The results of Mendels experiments on dominant and recessive inheritance led to Mendel s first law: the law of segregation. 孟德爾關于顯性和隱性遺傳的實驗結果導致了孟德爾第一定律-分離定律的產(chǎn)生,35,This law states that for a given trait an organis

25、m inherits one allele from each parent.這個定律說的是生物只遺傳父母本等位基因?qū)Φ囊粋€等位基因,36,Together these alleles form the allele pair. When gametes are formed during meiosis, the two alleles become separated(halving of chromosome number).這些基因一起形成基因?qū)Αp數(shù)分裂期形成配子時兩個等位基因分離,37,To gain evidence for his theory Mendel performed

26、 test crosses, mating(使配對使交配) plants of unknown genotype to plants that were homozygous recessive for the trait of interest.為驗證此理論，他做了測交實驗，即基因型未知的植物與純合的隱性基因植物雜交,38,The ratio of dominant phenotype(if any) in the progeny makes clear whether the unknown genotype is heterozygous, homozygous dominant, or

27、 homozygous recessive.通過子代中顯性表型的比率可以明確測得未知基因型是雜合的或純合顯性的或者純隱性的,39,4. Mendels ideas and the law of independent assortmentMendel also performed dihybrid cross, which enabled him to consider how traits are inherited relative to one another.孟德爾還進行了雙因子雜合子雜交試驗，這個實驗使他仔細考慮兩個特征是如何相互影響遺傳的,40,This work led to t

28、he law of independent assortment, which states that the alleles of genes governing different characters are inherited independently.試驗結果產(chǎn)生獨立分配定律，即控制不同特征的等位基因獨立遺傳,41,An apparent exception to Mendels laws is incomplete dominance, a phenomenon in which offspring of a cross exhibit a phenotype that is i

29、ntermediate中間的 between those of the parents.特例是不完全顯性。子代的表型是父母本的中間類型,42,Mendel presented his ideas in 1866 in a scientific paper published by the Brunn Society for Natural History. 1866年，孟德爾在由布魯恩自然歷史學會出版的期刊上發(fā)表了他的科學論文，陳訴了他的觀點,43,Unfortunately, the meaning of his research was not understood by other scientists of the day.His work was r