第八章核外遺傳打印稿

1、nOrganelle heredity（細(xì)胞器遺傳）nInfectious heredity（感染型遺傳）nMaternal effect（母性影響）第八章 核外遺傳核外遺傳 Extranuclear Inheritance第一節(jié) 細(xì)胞器遺傳 Organelle heredityCytoplasmic inheritance（細(xì)胞質(zhì)遺傳）一、葉綠體遺傳葉綠體遺傳(chloroplast heredity)1. Variegation（花斑） in Four Oclock Plant 2. Drug resistance in Chlamydomonas 衣藻抗性的遺傳 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 葉綠體基因組二、線粒體遺傳(Mitochondrial heredity)1. The poky mutation in Neurospora 鏈孢霉緩慢生長(zhǎng)突變型（poky）2. Petite in Saccharomyces（釀酒酵母）nSegregational petites 分離型小菌落 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 線粒體基因組 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肌陣攣性癲癇與破損性紅肌纖維病The proportion of mutant mitochondria determines the severity of the MERRF phenotype and the tissue that are affectedlebers hereditary optic neuropathy，LHONleber氏遺傳性視神經(jīng)病Keams-Sayre SyndromeKSS綜合征 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（氧化磷酸化反應(yīng)）， 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（單親遺傳）, mainly maternal inheritance （母系遺傳）nMitotic segregation 第二節(jié) 感染性遺傳 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 草履蟲(chóng)卡巴粒的遺傳2. Infective particles in DrosophilanCO2 sensitivity: caused by a virus nSex-ratio（性比因子） : protozoan（原生動(dòng)物） 第三節(jié) 母性影響 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 歐洲麥蛾幼蟲(chóng)色素的遺傳 2. Limnaea（椎實(shí)螺） coiling 3. Embryonic development in Drosophila 果蠅胚胎發(fā)育中的母性影響果蠅胚胎發(fā)育中的母性影響 第四節(jié) 植物細(xì)胞質(zhì)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（雜交種）.nS: male sterility cytoplasm（雄性不育細(xì)胞質(zhì)）nN: normal cytoplasm（正常細(xì)胞質(zhì)）nRf: a nuclear restorer/suppressor gene of S （雄性不育的恢復(fù)/抑制