染色體畸變結(jié)構(gòu)改變(參考版)
2025-05-04 22:58本頁(yè)面
【正文】 。 ) 理論意義：首次證實(shí)了一種染色體畸變與一種特異性腫瘤的關(guān)系，為 Boveri提出的“腫瘤染色體理論”提供了實(shí)驗(yàn)證據(jù) , 是腫瘤遺傳學(xué)研究的里程碑。22) (22pter→22q11::9q34→9qter) 1973年， Rowley 采用顯帶技術(shù)證實(shí) Ph染色體 der(22)(9。 （ 2）易位雜合體半不育 ?出現(xiàn)假連鎖現(xiàn)象 —— 因易位改變了基因間的連鎖關(guān)系，使本應(yīng)獨(dú)立遺傳的基因出現(xiàn)連鎖 —— 假連鎖。相鄰式分離：產(chǎn)生 可育配子 ?(2)相互易位純合體：同源染色體聯(lián)會(huì)一切正常 。 (2)相互易位 (reciprocal translocation)： 指兩個(gè)非同源染色體都被折斷，兩個(gè)斷片交換重接到兩條被折斷的非同源染色體上的現(xiàn)象。 倒位純合的同源染色體聯(lián)會(huì)完全正常 ， 但會(huì)產(chǎn)生 “ 位置效應(yīng) ” 。 ? 倒位的 遺傳效應(yīng) （ 2） 對(duì)育性的影響：倒位雜合體倒位環(huán)內(nèi)發(fā)生交換后 ，產(chǎn)生的交換型配子 (50%)含重復(fù)缺失染色單體 ， 這類配子不育 。 Inversion Loop ? Inversions do not change the geic content of a cell, however they have consequences for meiotic products (gametes) ? Top: diagram of inversion loop ? Bottom: EM micrograph of inversion loop during meiosis in a mouse cell Inversion Loop （倒位環(huán)） Chromosomes with inverted regions can form “inversion loops” when pairing occurs during meiosis. Paracentric Inversion Crossover A crossover involving a paracentric inversion (when the centromere is not in the inverted region) produces altered chromosomes. One product has no centromere (acentric), one has two centromeres (dicentric). Pericentric Inversion Crossover A crossover involving a pericentric inversion (when the centromere is in the inverted region) produces altered chromosomes. One product has gained geic material (a duplication), one has lost geic material (a deletion). Dicentric Chromosomes are Unstable ? Dicentric chromosomes can be formed from crossover
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