實(shí)驗(yàn)七果蠅的雜交試驗(yàn)

實(shí)驗(yàn)七果蠅的雜交試驗(yàn)一、實(shí)驗(yàn)?zāi)康牧私獍樾赃z傳和常染色體遺傳的區(qū)別；進(jìn)一步理解和驗(yàn)證伴性遺傳和分離、連鎖交換定律；學(xué)習(xí)并掌握基因定位的方法。二、實(shí)驗(yàn)原理紅眼與白眼是一對(duì)相對(duì)性狀，控制該對(duì)性狀的基因（W）位于X染色體上，且紅眼（W）對(duì)白眼（w）為完全顯性。當(dāng)紅眼雌蠅與白眼雄蠅雜交時(shí)，無(wú)論雌雄均為紅眼，F(xiàn)2中紅眼:白眼=3:1，但雌蠅全為紅眼，雄蠅中紅眼:白眼=1:1；反交時(shí)F1中雌蠅為紅眼，雄蠅為白眼，F(xiàn)2中紅眼:白眼=1:1，雌蠅和雄蠅中的紅眼與白眼的比例均為1:1。 正常翅（Sn3）對(duì)小翅（sn3）為顯性，正常剛毛（M）對(duì)焦剛毛（m）為顯性，與紅眼（W）和白眼（w）一樣，均位于（X）染色體上。利用三點(diǎn)測(cè)交的方法只需通過(guò)一次雜交和一次測(cè)交就能同時(shí)確定三個(gè)基因在染色體上的位置順序和基因的相對(duì)距離，繪出連鎖圖。 讓白眼小翅焦剛毛♀蠅與野生型♂蠅雜交，F(xiàn)1雌蠅是三雜合體：表型為野生型。F1♂蠅是白眼焦剛毛小翅。F1代的雌雄蠅互交實(shí)際上相當(dāng)于三雜合體雌蠅與三隱性雄蠅的測(cè)交。通過(guò)對(duì)互交后代中各種表型比例的分析，就可進(jìn)行w、sn3和m等基因的定位。三、實(shí)驗(yàn)材料

野生型雄蠅、雌蠅、白眼焦剛毛小翅雌雄蠅。

四、實(shí)驗(yàn)器具和藥品

1.器具：放大鏡、顯微鏡、麻醉瓶、白瓷板、毛筆、記錄本。2.藥品：乙醚、酒精棉球、培養(yǎng)基。

五、實(shí)驗(yàn)步驟

1.選處女蠅

選白眼焦剛毛小翅處女蠅5～10只，同時(shí)選野生型處女蠅5～10只。方法:將野生型和白眼焦剛毛小翅果蠅培養(yǎng)瓶?jī)?nèi)的成蠅全部趕去，12小時(shí)內(nèi)將重新孵化出的雌雄果蠅分開(kāi)，即可得所需處女蠅和雄蠅。

2.雜交

將白眼焦剛毛小翅處女蠅麻醉，并挑取野生型♂蠅5～10只麻醉后放入培養(yǎng)瓶，此雜交組合可用作伴性遺傳和基因定位的觀察統(tǒng)計(jì)。將野生型處女蠅5～10只麻醉，同時(shí)將同樣數(shù)量的白眼焦剛毛小翅雄蠅麻醉，放入培養(yǎng)瓶，此組合用于分離定律和伴性遺傳實(shí)驗(yàn)的反交。貼好標(biāo)簽。注明雜交組合和日期，學(xué)生姓名。接種一天后檢查成活情況，死亡應(yīng)及時(shí)補(bǔ)充。

3.25℃條件下培養(yǎng)7～8天后，趕去親本蠅。

4.觀察F1

11～13天后，F(xiàn)1代羽化，用放大鏡對(duì)正交組合的F1進(jìn)行觀察，看F1雌蠅是否為野生型，雄蠅是否全為三隱性，若不是，表明處女蠅是非處女蠅，實(shí)驗(yàn)失敗。

5.F1互交

正、反交各選5～10對(duì)F1雌雄蠅麻醉，轉(zhuǎn)入新的培養(yǎng)瓶，貼好標(biāo)簽。6.放飛F1

7～8天后趕去F1。

7.觀察F2

11～13天后，F(xiàn)2羽化，將其麻醉后于白瓷板上用放大鏡觀察，或用解剖鏡、顯微鏡觀察各種表型的果蠅并統(tǒng)計(jì)數(shù)目，每隔2天觀察一次，連續(xù)3～4次，統(tǒng)計(jì)總數(shù)約200～300只。統(tǒng)計(jì)后的果蠅倒入死蠅盛留器中。六、實(shí)驗(yàn)結(jié)果

1.分離定律：只觀察一對(duì)相對(duì)性狀的遺傳情況，并對(duì)觀察結(jié)果進(jìn)行遺傳分析。2.伴性遺傳：只觀察一對(duì)相對(duì)性狀（如紅眼和白眼）伴隨性別的遺傳情況，并填表?；蚨ㄎ唬和瑫r(shí)觀察三對(duì)相對(duì)性狀，但只用正交組合的F2代數(shù)據(jù)，并將觀察結(jié)果填表。七、作業(yè)及思考題

1.分析和解釋分離規(guī)律的實(shí)驗(yàn)結(jié)果。2.分析和解釋伴性遺傳的實(shí)驗(yàn)結(jié)果。3.計(jì)算X染色體上三個(gè)基因之間的重組值，確定它們的位置，作出連鎖圖。4.寫(xiě)出實(shí)驗(yàn)報(bào)告。5.你在實(shí)驗(yàn)中有什么新的發(fā)現(xiàn)？如何進(jìn)行解釋？

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