导致的声带发育不全课件

《导致的声带发育不全课件》由会员上传分享，免费在线阅读，更多相关内容在教育资源-天天文库。

1、Invdup(15)导致的声带发育不全、智障、发育迟缓、脊椎弯曲、孤独症6.1.3Inversions(倒位)Inversionsturnpartofthechromosomearound,reversingitspolarity.Achromosomewithaninversioncanpairwithanormalchromosomeinmeiosisinaheterozygoteandformaninversionloop.倒位纯合体完全正常，不影响个体生活力。倒位杂合体同源配对形成倒位环“i

2、nversionloop”，倒位片段上的基因在连锁群中的排序也改变了。Meioticrecombinationwithinaninversionloopduplicatesoneendofeachchromatidanddeletestheotherendinareciprocalmanner.Theserecombinedchromatidsarethereforenotviable,anddonotreachthenextgeneration.6.1.3.1Paracentricinversio

3、ns(臂内倒位）jihefgdcbaabcbadcdjihefgcbaParacentricinversions(臂内倒位）Thesedonotincludethecentromere.Meioticrecombinationinaparacentricinversionloopgeneratesadicentricchromatid(twocentromeres)andanacentric(nocentromere)fragment.Mostdipterans(truetwo-wingedflie

4、s)cantoleratethisbecausetheyhavenorecombinationinmalessospermallcontaincompletechromosomes,andfemaledipteranshavemechanismstoensurethatonlyunrecombinedchromatidsreachtheeggcell,sozygotesareviable.臂内倒位（paracentricinversions）：着丝粒在倒位环外，环内发生片段交换重组，减数分裂后期出现

5、“桥”和“断片”——一条染色单体含双着丝粒，另一条无着丝粒6.1.3.2Pericentricinversions(臂间倒位）Pericentricinversions(臂间倒位）Theseinvertthecentromericregion.Theeffectsofmeioticrecombinationintheloopduplicatinganddeletingtheendsofthechromatidcannotbeavoidedbecauseallchromatidshaveonecent

6、romere.Manyzygoteswillhaveunbalancedgenomes.Pericentricinversionsonlypersistaspolymorphismsinspecieswheretheydonotrecombineatmeiosis.臂间倒位（pericentricinversions）:着丝粒在倒位环內，环内发生交换重组，染色单体产生缺失或重复，形成不平衡配子，无生活力。遗传效应：染色单体发生交换后产生缺失和重复的不育配子，存活的配子应是未发生交换重组的。倒位可以抑

7、制和大大降低倒位环内的基因重组。6.1.4Translocations易位是非同源染色体间的片段交换Flash-Robertsonian双语课件中纯合体易位没有明显的细胞学特征，与未易位相似。杂合体易位体同源配对出现十字形图，随着着丝点趋向两极，成圆形或8字，各50%概率倒“8”字交替式不育上下相邻可育“O”型交替式可育相邻不育Translocationsinvolveexchangeofdistalregionsofnonhomologouschromosomes.Itisnecessarytha

8、teitherbothrearrangedorbothoriginalchromosomesoccurinthesamegametetoensuregeneticbalance.Iftwoadjacentchromosomessegregatetothesamepole,geneticallyunbalancedgameteswillbeproduced,butifalternatedchromosomesgotogether,thegameteswillcontai