问答题
用枯草杆菌的一个a+b+c+作为供体，提取其DNA向受体a-b-c-菌株进行转化，结果如下：
试问：
(1)三个基因的连锁次序如何?
(2)各基因之间的连锁距离为多少?
(3)请作出连锁图。
| 座位 | 转化类别 | ||||||
| a b c | - - + | - + - | + - - | - + + | + - + | + + - | + + + |
| 700 | 400 | 2600 | 3600 | 100 | 1200 | 12000 | |
(1)三个基因的连锁次序如何?
(2)各基因之间的连锁距离为多少?
(3)请作出连锁图。
【正确答案】三基因连锁顺序为：abc
R(a—b)=(400+2600+3600+100)/[(400+2600+3600+100)+(1200+12000)]×100%
=6700/19900×100%
=0.3366×100%
=34%
R(b—c)=(700+400+100+1200)/[(700+400+100+1200)+(3600+12000)]×100%
=2400/18000×100%
=0.1333×100%
=13%
R(a—c)=(700+2600+3600+1200)/[(700+2600+3600+1200)+(100+12000)]×100%
=8100/20200×100%
=0.4×100%
=40%
R(a—b)=(400+2600+3600+100)/[(400+2600+3600+100)+(1200+12000)]×100%
=6700/19900×100%
=0.3366×100%
=34%
R(b—c)=(700+400+100+1200)/[(700+400+100+1200)+(3600+12000)]×100%
=2400/18000×100%
=0.1333×100%
=13%
R(a—c)=(700+2600+3600+1200)/[(700+2600+3600+1200)+(100+12000)]×100%
=8100/20200×100%
=0.4×100%
=40%
【答案解析】