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

1、1,Foundations of Genetics（遺傳學(xué)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(jié)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(xué)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(xué)說：德國生物學(xué)家A.魏斯曼1892年提出的有關(guān)遺傳物質(zhì)的學(xué)說，認(rèn)為多細(xì)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(xì)胞的染色體上,種質(zhì)可以發(fā)育為新個(gè)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(chǔ)，體質(zhì)可以通過生長和發(fā)育而形成為新個(gè)體的各個(gè)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(gè)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(xué)說又稱為種質(zhì)連續(xù)學(xué)說。為后來T.H.摩爾根開創(chuàng)的細(xì)胞遺傳學(xué)和對遺傳物質(zhì)的深入探索奠定了理論基礎(chǔ),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(dú)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(gè)性,個(gè)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(shè)) 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(xué)的早期理論包括Hippocrates的泛生說和A.Weismann的種質(zhì)學(xué)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(xué)之父”的古希臘著名醫(yī)生，歐洲醫(yī)學(xué)奠基人，古希臘醫(yī)師，西方醫(yī)

11、學(xué)奠基人。提出“體液(humours)學(xué)說”，認(rèn)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(rèn)為醫(yī)師所應(yīng)醫(yī)治的不僅是病而是病人；從而改變了當(dāng)時(shí)醫(yī)學(xué)中以巫術(shù)和宗教為根據(jù)的觀念。主張?jiān)谥委熒献⒁獠∪说膫€(gè)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(yù)后。他對骨骼、關(guān)節(jié)、肌肉等都很有研究。他的醫(yī)學(xué)觀點(diǎn)對以后西方醫(yī)學(xué)的發(fā)展有巨大影響,17,August Weismann，(18341914)德國動(dòng)物學(xué)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(xué)學(xué)醫(yī) 。先后在巴登和奧地利當(dāng)過軍醫(yī)和私人開業(yè)醫(yī)生。1861年在吉森大學(xué)從師于德國動(dòng)物學(xué)家K.G.洛伊卡爾特，學(xué)習(xí)動(dòng)物發(fā)生學(xué)及形態(tài)學(xué)，1863年完成了關(guān)于雙翅目昆蟲變態(tài)的論文。1866年擔(dān)任弗賴堡大學(xué)醫(yī)學(xué)系動(dòng)物學(xué)和比較解剖學(xué)副教授，1868年在該校創(chuàng)辦動(dòng)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(zhuǎn)向遺傳、發(fā)生和進(jìn)化問題的理論探討。他講授達(dá)爾文進(jìn)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(shí)驗(yàn)，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(gè)早期觀點(diǎn)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(xué)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(dāng)他還是大學(xué)生時(shí)就提出了物質(zhì)的粒子屬性理論，同時(shí)他學(xué)習(xí)數(shù)學(xué)。孟德爾進(jìn)行了一系列周密安排的實(shí)驗(yàn)來證實(shí)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(jìn)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(xué)學(xué)習(xí)數(shù)學(xué)和自然科學(xué)。從1854年到1868年在布魯恩現(xiàn)代學(xué)校擔(dān)任自然科學(xué)代課教師。與此同時(shí)，孟德爾從1856年起開始進(jìn)行他的著名的植物育種實(shí)驗(yàn)。1865年他推導(dǎo)出了著名的遺傳學(xué)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(xué)會(huì)。1866年他的成果被發(fā)表在該學(xué)會(huì)學(xué)報(bào)上，題目是“植物雜交實(shí)驗(yàn)”。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(huì)會(huì)長，專職行政事務(wù)。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(shí)驗(yàn)研究遺傳學(xué)，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(dòng)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(yàn)證融合理論，他的研究主要集中在7個(gè)明顯特征上。例如，種子顏色，植株高度，這些特征只有兩個(gè)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(jié)

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(gè)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(gè)個(gè)體僅擁有兩個(gè)研究遺傳單元，并且每個(gè)單元來自一個(gè)親代時(shí)，實(shí)驗(yàn)結(jié)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(gè)一樣的等位基因決定一個(gè)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(dāng)生物是雜合時(shí)，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(shí)含有一個(gè)顯性基因和一個(gè)隱性基因,33,A pictorial(形象化的生動(dòng)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(guān)于顯性和隱性遺傳的實(shí)驗(yàn)結(jié)果導(dǎo)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(gè)定律說的是生物只遺傳父母本等位基因?qū)Φ囊粋€(gè)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)?。減數(shù)分裂期形成配子時(shí)兩個(gè)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(yàn)證此理論，他做了測交實(shí)驗(yàn)，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(jìn)行了雙因子雜合子雜交試驗(yàn)，這個(gè)實(shí)驗(yàn)使他仔細(xì)考慮兩個(gè)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(yàn)結(jié)果產(chǎn)生獨(dú)立分配定律，即控制不同特征的等位基因獨(dú)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(xué)會(huì)出版的期刊上發(fā)表了他的科學(xué)論文，陳訴了他的觀點(diǎn),43,Unfortunately, the meaning of his research was not understood by other scientists of the day.His work was r