染色體畸變結構改變(編輯修改稿)
2025-05-28 22:58 本頁面
【文章內(nèi)容簡介】 ct)”。 果蠅復眼的小眼組成數(shù)目的 劑量效應 Duplication may be caused by unequal crossover in meiosis. （三） Inversion (1)臂內(nèi)倒位 (Paracentric inversion)： 指倒位發(fā)生在染色體的某一臂內(nèi)，又稱為一側倒位。 (2)臂間倒位 (Pericentic inversion)： 指倒位發(fā)生在兩臂之間（含著絲粒），又稱為兩側倒位。 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 crossovers involving inversions, or in mitotic cells by “healing” of broken ends. ? Dicentrics undergo a cyclic “breakagefusionbridge” during repeated cell divisions. ? 倒位的細胞學鑒定 ?細胞學特征 同源染色體聯(lián)會時： 倒位區(qū)段過長 —— 倒過來，其余游離 倒位區(qū)段較短 —— 正常部分配對，其余不配對
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