物理化學(xué)老師遺傳學(xué)lecture one

1、GeneticsYueping CAOPlant Science一.受精的過程(一) 胚珠的結(jié)構(gòu)珠孔珠被卵細(xì)胞極核子房壁果皮和種子分別由子房的哪部分發(fā)育而來?子房2n子房壁胚珠果皮2n種子果實(shí)種子的這些結(jié)構(gòu)又是由胚珠的哪些部位發(fā)育而成的?胚珠珠被受精卵受精極核種皮2n胚2n胚乳3n種子Mitosis(有絲分裂) and Meiosis（減數(shù)分裂）-The transmission and segregation of genes is determined by the movement of chromosomes through mitosis and meiosis. 基因的傳遞和分離決

2、定于染色體在有絲分裂和減數(shù)分裂中的行為-Mitosis and meiosis only occur in eukaryotes, not present in prokaryotes. 有絲分裂和減數(shù)分裂只發(fā)生在真核生物Prokaryotic cellsEukaryotic cellsTaxonomic groupBacteriaAll plants, fungi, animals, Protists（原生生物）Sizetypically 5 mNucleusno true nuclear membranenuclear membraneGenetic materialOne circula

3、r molecule of DNA, little proteinLinear molecule of DNA and proteinMitosis and meiosisAbsentPresentDifferences between prokaryotic and eukaryotic cells.真核細(xì)胞和原核細(xì)胞的區(qū)別Eukaryotic cells are of two types:Somatic cells - Any cell in a higher organism that is not a reproductive cell. 2n designates the somat

4、ic chromosome complement. 在高等生物中，除了生殖細(xì)胞以外的任何細(xì)胞都是體細(xì)胞。Examples: cells in the skin, muscle cells, cells in roots.Gametic cells - Reproductive cells. Gametic cells have 1/2 the chromosome complement of somatic cells. Examples: Plants egg and pollen cellsAnimals - egg and sperm cells.Examples of the numb

5、er of chromosome in various species -Most animal somatic cells are _Diploid_. Diploid cells have _2_ sets of chromosomes. Most animal gametic cells are _Haploid_. Haploid cells have _1_ set of chromosomes.-Plant species vary in the number of sets of chromosomes. For example, wheat is a _Hexaploid_ w

6、ith _6_ sets of chromsomes. No. of chromosomesSpecies2n nHumans4623Maize2010Dog7839Indian fern1260630Australian ant21Homologous chromosome（同源染色體）Chromosomes -During mitosis and meiosis, stained chromosomes are visible with a light microscope.在有絲分裂列和減數(shù)分裂過程中在光學(xué)顯微鏡下可以看到染色體。 -What are chromosomes compos

7、ed of? 染色體的組成是: DNA, protein and RNAHomologous chromosomes - a pair (in diploids) of essentially identical chromosomes that join and bine DNA in meiosis. 同源染色體是是在減數(shù)分裂中可以重新結(jié)合在一起的大小形態(tài)相同的染色體（體條來自父本，一條來自母本）。 -Humans have 23 pairs of homologous chromosomes. -Chromosomes can be classified based on size an

8、d position of centromere. -Homologous chromosomes are the same size with the exception of the sex chromosomes.Homologous chromosomes-Chromosomes can be classified based on size and position of centromere. -Homologous chromosomes are the same size with the exception of the sex chromosomes.Below are 2

9、 homologous chromosomes. One of these chromosomes would be from this individuals mother and the other from the father. Each homologous chromosome consists of two chromatids. The two chromatid on a chromosome contain identical genetic information. This information was recently replicated during the S

10、 phase of the cell cycle. The two homologous chromosomes would carry alternative alleles for genes. For example, if the individual is heterozygous Aa, one homologous chromosome would carry the A allele and the other chromosome would carry the a allele. Because two chromatids on the same chromosome c

11、arry identical genetic information, both chromatid 1 and 2 would carry the A allele and chromatids 3 and 4 would carry the a allele.Humans have 23 pairs of homologous chromosomesChromatid 2Chromatid 3Chromatid 4Chromatid 1 Chromatid 1Homologous chromosomes of humanMitosis（有絲分裂）Mitosis - Nuclear divi

12、sion with each daughter cells receiving an identical complement of chromosomes. 有絲分裂-核分裂每個(gè)子細(xì)胞得到一套完整相同的染色體-Mitosis is only a part of the cell cycle. 有絲分裂僅僅是細(xì)胞周期的一部分Mitosis（有絲分裂）Mitosis is about 10% of the time of the cell cycle. This is when cell division occurs. During G1, metabolic activity occurs

13、and this stage takes about 25% of the time of the cell cycle. During the S stage, DNA replication occurs and this takes about 40% of the cell cycle time. Metabolic activity occurs during G2 and this stage takes the remaining 25% of the cell cycle.Rapidly dividing eukaryotic cells can go through the

14、entire cycle in 16 hours.Synthesis stage (S)G1 stage MitosisG2 stageCell CycleStages of Mitosis（有絲分裂的時(shí)期） Mitosis is a continuous process but it can be divided into four stages（有絲分裂是一個(gè)連續(xù)的過程，分4個(gè)時(shí)期）.1. Prophase（前期） Chromosomes condense, nuclear membrane disintegrates.2. Metaphase（中期） - Mitotic spindle

15、forms, chromosomes e attached to the spindle and the chromosomes line up at the central plane.3. Anaphase （后期）- Chromosomes divide longitudinally. One sister chromatid moves to each pole.4. Telophase（末期） - Nuclear membrane reforms, cell division occurs. Stages of Mitosis- Interphase Interphase (間期)

16、Stages of Mitosis- prophase Prophase （前期） . Chromosomes condense, nuclear membrane disintegrates. Stages of Mitosis- Metaphase centromereMetephase（中期） Mitotic spindle forms, chromosomes e attached to the spindle and the chromosomes line up at the central planeStages of Mitosis- Anaphase Anaphase （后期

17、）- Chromosomes divide longitudinally. One sister chromatid moves to each pole.Stages of Mitosis- TelophaseTelophase（末期） - Nuclear membrane reforms, cell division occursMeiosis（減數(shù)分裂）Meiosis - The process in gametogenesis or sporogenesis during which one replication of the chromosomes is followed by t

18、wo nuclear divisions to produce four haploid cells. 減數(shù)分裂-在配子體形成過程中，染色體復(fù)制1次進(jìn)行2次核分裂，形成4個(gè)單倍體細(xì)胞。Stages of Meiosis（減數(shù)分裂的時(shí)期）Prophase I - Chromosomes condense and pair, crossing over between homologous chromosomes occurs（染色體濃縮，同源染色體配對(duì)，交換）.Metaphase I - Homologous chromosomes line up at the metaphase plane.

19、 The orientation of the chromosomes is random.同源染色體排列在赤道板兩側(cè)，染色體的朝向（被分配到哪極）是隨機(jī)的Anaphase I - Homologous chromosomes separate. This is referred to as a reductional division.同源染色體分離，即所說的減數(shù)分裂。Telophase I - Cells divide.細(xì)胞分裂。There is no chromosome replication between meiosis I and meiosis II.減數(shù)分裂的第一次分裂和第二

20、次分裂之間沒有染色體的復(fù)制Prophase II -This is brief as the chromosomes are already condensed from meiosis I.Metaphase II - Chromosomes line up on the metaphase plane.Anaphase II - Chromosomes divide. This is referred to as the equational division.Telophase II - Cells divide.Prophase I - As prophase progresses,

21、chromosomes are pairing and crossing over occurs.Stages of meiosis- Prophase I Chromatid 1 細(xì)線期偶線期粗線期？雙線期？終線期Metaphase IAnaphase ITelophase I減數(shù)分裂的意義形成雌雄配子時(shí)染色體減半n，雌雄配子結(jié)合形成新的合子，恢復(fù)原來的染色體數(shù)2n,保持物中的穩(wěn)定在減數(shù)分裂的第一次分裂的前期，部分同源染可以發(fā)生交換，另外在后期同源染色體的分到兩極是獨(dú)立的，隨機(jī)，因此使后代產(chǎn)生變異，給予物種豐富的多樣性。Meiosis produces genetic variability

22、 two ways減數(shù)分裂產(chǎn)生遺傳變異有兩個(gè)來源 How does this create genetic variability?Independent assortment of chromosomes. （染色體的獨(dú)立分配） This creates new combinations of genes on chromosomes.(染色體上的基因產(chǎn)生了新組合)Crossing over.（交換：非姊妹染色單體之間） Creates new combinations of chromosomes.新組合的染色體產(chǎn)生How do genes segregate during meiosis

23、?（減數(shù)分裂中基因的分離）Genes segregate independently during meiosis. What happens is that if an individual has the genotype AaBb, it will produce the following gametes: 1/4 AB, 1/4 Ab, 1/4 aB, 1/4 ab assuming that A and B are on different chromosomes. The reason we have the four different gametes products is

24、that whether the chromosome carrying A or a are on the left side of the metaphase plate is random. The same is true for B and b. The following are two possible orientations of the chromosomes.如果基因型是AaBb ，減數(shù)分裂后將產(chǎn)生下列4種配子：1/4 AB, 1/4 Ab, 1/4 aB, 1/4 ab 。原因如下： 假設(shè)A和B在不同的染色體上， 攜帶A 或 a的染色體在赤道板的左側(cè)或右側(cè)是隨機(jī)的，因此

25、染色體的分配朝向有兩種可能（2），同樣攜帶 B 和 b的染色體也是這樣（2）。2*2=4After meiosis II, the gametes AB and ab would be produced from the cell on the left and the gametes Ab and aB would be produced from the cell on the right. 減數(shù)分裂后，配子AB 和 ab將產(chǎn)生于細(xì)胞的左側(cè)， Ab 和 aB將產(chǎn)生于細(xì)胞的右側(cè)。 Differences between Mitosis and Meiosis有絲分裂和減數(shù)分裂的區(qū)別Mitos

26、isMeiosisCell typeSomaticReproductiveFunctionGrowth and repairGamete formationDaughter cell chromosome no.DiploidHaploidDaughter cell genotypesIdenticalDifferDo homologspair?NoYesDoes crossing over occur?NoYes遺傳信息的傳遞規(guī)律和物質(zhì)基礎(chǔ) 孟德爾定律孟德爾實(shí)驗(yàn) 用32個(gè)品種,觀察了7對(duì)性狀,經(jīng)8年研究， 發(fā)現(xiàn)了2個(gè)定律: 獨(dú)立分配,自由組合定律 創(chuàng)立了“ 遺傳學(xué) ”表 11 孟德爾的豌豆雜

27、交實(shí)驗(yàn)7對(duì)性狀的結(jié)果 2.84:1277矮787高高植株高植株矮植株3.14:1207頂生651腋生腋生花腋生花頂生2.82:1152黃428綠綠色綠色黃色豆莢2.95:1299癟882鼓鼓脹膨大縊縮豆莢3.15:1224白705紫紫花 紫花白花3.01:12001綠6022黃黃色黃葉綠色子葉2.96:11850皺5474圓圓形圓形皺縮子葉F2比例 F2F1 豌豆表型 2. 雜種1代的觀察： （filial generation 1，F(xiàn)1 ) 確定了 顯性（dominate）性狀 隱性 (recessive)性狀From these experiments, Mendel derived th

28、e following postulates of inheritance:1. Traits are controlled by unit factors that are in pairs. Genetic characters are controlled by unit factors that exist in pairs in individual organisms.形狀是由一對(duì)遺傳因子控制。2. Dominance/Recessiveness. When two unlike unit factors responsible for a single character are

29、 present in a single individual, one unit factor is dominant to the other.兩個(gè)相似的遺傳因子控制一個(gè)形狀，一個(gè)對(duì)另一個(gè)是顯性。3. Segregation. During the formation of gametes, the paired unit factors separate or segregate randomly so that each gamete receives one or the other with equal likelihood.在形成配子的時(shí)候，這對(duì)遺傳因子隨機(jī)分離，每個(gè)配子得到一份

30、。（三）精確驗(yàn)證 創(chuàng)用測(cè)交方法對(duì)推論加以驗(yàn)證 測(cè)交（test cross）： 是指將雜種后代和隱性親本進(jìn)行雜交， 回交（back cross）： 是指雜種后代和任一親本雜交。 第二節(jié) 孟德爾定律（Mendels laws） 對(duì)一對(duì)性狀的觀察得出了三條規(guī)律 （1）F1代的性狀一致，通常和一個(gè)親 本相同。得以表現(xiàn)的性狀為顯性， 未能表現(xiàn)的性狀稱隱性，此稱F1一 致性法則。（2）在雜種F2代中，初始親代的二種 性狀（顯性和隱性）都能得到表達(dá)；（3）這兩性狀的比例總為 3：1。一 分離律（Law of segregation） 1分離律的實(shí)質(zhì) 控制性狀的一對(duì)等位基因在產(chǎn)生配子時(shí) 彼此分離，并獨(dú)立地分配

31、到不同的性細(xì) 胞中。 2分離律的意義 具有普遍性 遺傳病約有4344種（1988年） 侏儒（先天性軟骨發(fā)育不全） 顯性 裂手裂足 舞蹈?。℉untington） 白化 半乳糖血癥 隱性 苯丙酮尿癥 全色盲 早老癥 自毀容貌綜合征 Learning Objectives for Unit 1.1) Understand the following terms: gene, allele, gamete, heterozygous, homozygous, genotype, phenotype, dominant, recessive, hybrid, backcross, testcross,

32、 homologous chromosomes, chromatids, crossing-over, centromere, haploid, diploid, somatic cell, gametic cell2) Know the stages of mitosis and meiosis and understand what happens during each stage.3) Understand the results of mitosis and meiosis.4) Understand the results and implications of independe

33、nt assortment and be able to diagram independent assortment of chromosomes during meiosis.Definitions:Gene - A physical unit of heredity whose existence can be confirmed by allelic variants and which occupies a specific chromosomal locus. Allele - Alternative forms of a given gene.Gamete A specialized reproductive cell with a haplo