支持突变的实验 雄成对培养繁育成100对 100个家系(每个家系中200对) 将每个家系分为2份(2×100家系) 份接触药物 份不接触药物 淘汰死亡率高的家系99个 选出与接触药物对应的死 亡率低的家系1个, 繁衍成100个家系,一分为二 一份接触药物 一份不接触药物 循环挑选、淘汰 得到抗性家系
一 雌、一雄成对培养繁育成100对 100个家系（每个家系中200对） 将每个家系分为2份（2×100家系） 一份接触药物 一份不接触药物 淘汰死亡率高的家系99个 循环挑选、淘汰 得到抗性家系 选出与接触药物对应的死 亡率低的家系1个， 一份接触药物 一份不接触药物 繁衍成100个家系，一分为二 支持突变的实验
老虎机与基因突变 The Luria-Delbruck experiment Hy pothesis 1: Resistance is a physiological response to a bactericide 1500d0d6 Hy pothesis 2: Resistance arises from random mutation 6000000000600000000000000 b Cultures ( Time of exposure to selective agent Salvador luria和 Max Delbruck的突变实验(1943年)
Salvador Luria和Max Delbruckd的突变实验（1943年） 老虎机与基因突变
影印培养法 无 Lederberg,1952年 用例压向平板里 再压向新鲜的 生长的克隆 培养基平板 图4-3细菌的影印培养装置图 给世界 平板 平板3
影印培养法 Lederberg, 1952年
Replica plating Make three replica 1. Invert master plate; 2. Invert second plate plates. Incubate to pressing against velvet replica plate); pressing allow penicillin surface leaves an imprint against velvet surface 107 colonies of resistant colonies of colonies. Save plate icks up colony imprint. penicillin-sensitive bacteria to grow s Master plate Penicillin Master plate Penicllin No penicillin in medium No penicillin in medium In medium 3. Incubate Velvet PenicillIn in medium 4. Only penicillin-resistant colonies grow. Compare position of colonies on original plate in medium Penicillin-resistant s= penicillin-sensitive bacteria colonies grow in the R= penicillin-resistant bacteria same position on all three plates
二、基因究变的概念和特 概念及其类别 1概念 point mutation Mutations: Are heritable changes in base sequences that modify the information content of DNA 2类另 Number of umber of Mutation Locus gametes tested mutations ate(X10-6) 根据基因突变的起源 a(albino 67,39 44 a自发突变 spontaneous mutation c (moag)1s b诱发突变 induced mutation2出 335045 33 332 119 根据突变后不同的表现型改变 2.220.376 12 (average a Mutation is from wildtype to the recessive allele shown a可见突变 Figure 6.3 Rates of spontaneous mutation. (a) Mutant mouse b条件致死突变 oat colors: albino(left ), brown(right).(b) Mutation rates from wildtype to recessive alleles of live coat-color genes Geneticists took C致死突交 animals from highly inbred strains with wildtype coat colors and mated therm with mice homozygous for recessive alleles of the five d生化突变 coat-color genes. The appearance of progeny with mutant coat colors indicated the presence of recessive mutations in gametes produced by the inbred mice
二、基因突变的概念和特征 概念及其类别 1 概念 point mutation Mutations:Are heritable changes in base sequences that modify the information content of DNA. 2 类别 * 根据基因突变的起源 a 自发突变 spontaneous mutation b 诱发突变 induced mutation * 根据突变后不同的表现型改变 a 可见突变 b条件致死突变 c 致死突变 d 生化突变