第八章核外遗传打印稿

1、nOrganelle heredity（细胞器遗传）nInfectious heredity（感染型遗传）nMaternal effect（母性影响）第八章 核外遗传核外遗传 Extranuclear Inheritance第一节 细胞器遗传 Organelle heredityCytoplasmic inheritance（细胞质遗传）一、叶绿体遗传叶绿体遗传(chloroplast heredity)1. Variegation（花斑） in Four Oclock Plant 2. Drug resistance in Chlamydomonas 衣藻抗性的遗传 15N mt+ 14N

2、mt Zygote（chloroplast DNA is 15N） 14N mt+ 15N mt Zygote（chloroplast DNA is 14N） The chloroplast DNA of the mt parent is lost after matingnThe shape of most cpDNAs is a circle ncpDNAs range in size from 120 to 217kb, most are between 120 and 160 kb longncpDNAs present in many copies per cellnGenes ar

3、e closely packednGenes contain intron3. The genome of chloroplast 叶绿体基因组二、线粒体遗传(Mitochondrial heredity)1. The poky mutation in Neurospora 链孢霉缓慢生长突变型（poky）2. Petite in Saccharomyces（酿酒酵母）nSegregational petites 分离型小菌落 results from nuclear gene mutationnNeutral petites 中性型小菌落 lost nearly complete mtDNA

4、nSuppressive petites 抑制型小菌落 nHypotheses for suppressive petite Mutant mtDNA replicates more rapidly, thus dominate by numbersRecombination occurs between the mutant and the wildtype mtDNA, and disrupts the normal mtDNAnmtDNAs of most species are circularnThe size of mtDNA differs greatly among organ

5、ismsnWith only rare exceptions, no introns present in mitochondrial genes and gene repetitions are few or nonenExpression of mitochondrial genes uses several modifications of genetic code.nMtDNA encodes some of the proteins that constitute the oxidative phosphorylation氧化磷酸化 system and encodes tRNAs,

6、 rRNAs, and some proteins used in mitochondrial protein synthesis3. Mitochondrial genome 线粒体基因组 4. Mutations in mtDNA cause human diseases Criteria for mitochondrial disease: Maternal inheritance Deficiency in bioenergetic function Mutation of mitochondrial gene Myoclonic epilepsy and ragged red fib

7、er disease，MERRF肌阵挛性癫痫与破损性红肌纤维病The proportion of mutant mitochondria determines the severity of the MERRF phenotype and the tissue that are affectedlebers hereditary optic neuropathy，LHONleber氏遗传性视神经病Keams-Sayre SyndromeKSS综合征 Mitochondrial inheritance in identical twins 2000 mtDNAs in an egg cell T

8、he mutant mitochondria in twins may end up in different cells Mitochondrial mutations and aging nMt DNA accumulate much more mutations than nuclear DNAnThe mutations result in an age-related decline in oxidative phosphorylation（氧化磷酸化反应）， which accounts for some symptomes of aging5. Mt DNA in genetic

9、 analysis Characteristics of mtDNAnMaternal inheritancenA lack of recombinationnA high variable non-coding region of 331bpnA large number of mtDNAs per cell mtDNA tests are used as evidence in kinship mtDNA and human emerged and evolved Summary of Organelle heredity Non-Mendelian inheritancenThe seg

10、regation ratio of parental alleles is 4 0 rather than 2 2 nUniparental inheritance（单亲遗传）, mainly maternal inheritance （母系遗传）nMitotic segregation 第二节 感染性遗传 Infectious Heredity Symbiotic bacteria and virus in the cytoplasm of certain cellsnKiller nKappa particle : 100200 in one cell, contain DNA and p

11、rotein, their maintenance depends on a dominant nuclear gene, K nKappa particles are bacterialike and may contain temperate bacteriophages. 1. Kappa in Paramecium 草履虫卡巴粒的遗传2. Infective particles in DrosophilanCO2 sensitivity: caused by a virus nSex-ratio（性比因子） : protozoan（原生动物） 第三节 母性影响 Maternal eff

12、ect An offsprings phenotype for a particular trait is under the control of nuclear gene products present in the egg.1. Ephestia pigmentation 欧洲麦蛾幼虫色素的遗传 2. Limnaea（椎实螺） coiling 3. Embryonic development in Drosophila 果蝇胚胎发育中的母性影响果蝇胚胎发育中的母性影响 第四节 植物细胞质雄性不育 Cytoplasmic Male Sterility in PlantsnMale ste

13、rility in plants is often cytoplasmically based and maternally inherited. nMale sterile plants produce no functional pollen, but do produce viable eggs. nCytoplasmic male sterility is used in agriculture to facilitate the production of hybrid seed（杂交种）.nS: male sterility cytoplasm（雄性不育细胞质）nN: normal cytoplasm（正常细胞质）nRf: a nuclear restorer/suppressor gene of S （雄性不育的恢复/抑制