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微生物出与高等动植物一样,能在没有人为的外界条件下自然发生突变,即自发突变。一、突变的种类从突变引起生物体表型的变化情况来看,可以把突变分成下列三类:(一)形态学的变化:如细菌细胞形态的改变,菌落形态的改变;(二)生理反应的变化:如原来能在合成培养基上生长的野生型的菌株,突变后的个体则要在培养基上添加某种生长因子才能生长了,说明细菌体内的生理反应发生了变化;(三)致死突变:由于微生物是单倍营养体的生物,虽然大多数的致死突变是隐性的,也不象高等生物那样能把隐性的致死突变基因保存下来,所以微生物在这类突变上的研究无法进行。但以后发现了一种条件性的致死突变,即这类突变个体在这一条件下是致死的,存另一条件下是能存活的。如某一微生物原来在20—40℃的温度范围内都能生长,但突变后的个
Like higher animals and plants, microorganisms can spontaneously mutate spontaneously without human external conditions. First, the type of mutation from the mutation caused by changes in the phenotype of the organism, the mutation can be divided into the following three categories: (A) morphological changes: such as bacterial cell morphology changes, changes in colony morphology; (B) Physiology Changes in the reaction: such as the original wild-type strains can be grown in synthetic medium, mutated individuals in the medium to add a growth factor to grow, indicating that bacterial physiological response has changed; (tris ) Lethal Mutations: Since organisms are haplogroups of organisms, most lethal mutations are recessive and are not preserved as lethal mutagenic genes, as higher organisms do Research can not be done. But later found a conditional lethal mutation, that such mutant individuals in this condition is lethal, save the other is able to survive. Such as a microorganism in the original 20-40 ℃ temperature range can grow, but after a mutation