遺傳學(xué)課件13第十三章細(xì)胞質(zhì)遺傳-文庫吧
2025-09-15 15:50 本頁面
【正文】 nglecopy region, SSC ( ~ 20 kb ) Inverted repeat, IRA and IRB ( 5 ~ 76kb ) SSC IR A IR B S S C : s h o r t s i n g l e c o p y s e q u e n c e L S C : l o n g s i n g l e c o p y s e q u e n c e I R : i n v e r t e d r e p e a t s L S C F i g . 1 9 T h e c h l o r o p l a s t g e n o m e i s a c i r c l e , d i v i d e d b y t w o i n v e r t e d r e p e a t s i n t o t h e s h o r t s i n g l e c o p y s e q u e n c e a n d l o n g s i n g l e c o p y s e q u e n c e ( G E N E S Ⅵ F i g 2 4 . 3 )葉綠體基因組編碼的總基因數(shù)目 : 100 ~ 120 個 分為三類主要基因 : 遺傳系統(tǒng)基因 光合系統(tǒng)基因 物質(zhì)合成基因 1. ctDNA與核 DNA復(fù)制相互獨(dú)立，但都是半保留 復(fù)制方式； 2. 葉綠體核糖體為 70S、而細(xì)胞質(zhì)中核糖體為 80S； 3. 葉綠體中蛋白質(zhì)合成需要的 20種氨基酸載體 tRNA分別由核 DNA和 ct DNA共同編碼。 4. 葉綠體的半自主性：有一套完整的復(fù)制、轉(zhuǎn)錄和翻譯系統(tǒng)，但又與核基因組緊密聯(lián)系。 如葉綠體中 RuBp羧化酶的生物合成 8個大亞基（由葉綠體基因組編碼） 8個小亞基（由核基因組編碼） ㈢ 、葉綠體 DNA的復(fù)制、轉(zhuǎn)錄和翻譯系統(tǒng) 第四節(jié) 線粒體遺傳 一、線粒體遺傳的表現(xiàn) 鏈孢霉生長緩慢型 酵母小菌落的遺傳 衣藻的線粒體遺傳 人類的線粒體病 線粒體夏娃 1. The poky Mutant of Neurospora ?1952年 Mary Mitchell分離了粗糙鏈胞霉菌(Neurospora)的小菌落（ poky): a slowgrowing strain ?poky♀ 野生型 ♂ → 后代全部為 poky。 ?野生型 ♀ poky♂ → 后代全部為野生型。 ?核外突變（ extranuclear mutaation） ?或細(xì)胞質(zhì)突變（ cytoplasmic mutation） 生長緩慢型 Explanation of the different results from reciprocal crosses of poky and normal Neurospora. The parent contributing most of the cytoplasm of the progeny cells is called female. Brown shading represents cytoplasm with the poky determinants. The nuclear locus with the alleles ad+ and ad is used to illustrate the segregation of the nuclear genes in the expected 1:1 Mendelian ratio. The Poky mutation resides in the mitochondrial genome . It disrupts the production of cytochromes, it is slow growing (as mentioned earlier), and it has abnormal amounts of mitochondrial cytochrome proteins. Like most anisms, wildtype Neurospora has three main types of cytochrome: a, b, and c . Poky, however, lacks cytochromes a and b and has an excess of cytochrome c. which results in defects in electron transport (energy deficiency). ? 1956， Boris Ephrussi 發(fā)現(xiàn) 小菌落酵母細(xì)胞缺少細(xì)胞色素 a和 b、缺少細(xì)胞色素氧化酶 ， 不能有氧呼吸，不能有效利用有機(jī)物，因此產(chǎn)生小菌落。 ? 分類 (1) 核基因突變型－ 孟德爾分離型 (2) 線粒體基因突變型－ 細(xì)胞質(zhì)遺傳型 2. Yeast petite Mutants 小菌落 正常線粒體 小菌落線粒體 Petite gene in Saccharomyces w Slow growth w Not able to do aerobic respiration w There is an interaction of the petites with various genotypes in the nucleus Cytoplasmic inheritance of the petite mutation in yeast. Petitestrain mitochondria are defective in oxidative phosphorylation due to a deletion in mtDNA. (a) Haploid cells fuse to produce a diploid cell that undergoes meiosis, during which random segregation of parental chromosomes and mitochondria containing mtDNA occurs. Since yeast normally contain 50 mtDNA molecules per cell, all products of meiosis usually contain both normal and petite mtDNAs and are capable of respiration. (b) As these cells grow and divide mitotically, the cytoplasm (including the mitochondria) is randomly distributed to the daughter cells. Occasionally, a cell is generated that contains
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