高中生物学遗传育种、基因工程、单克隆抗体制备、微生物的分离等教学内容都涉及到筛选的问题,近年高考也常以其作为命题素材,现对筛选问题简要归纳并结合例题分析如下。一、遗传育种中的筛选问题为获得所需要的生物类型,在杂交育种、诱变育种、单倍体育种及利用基因工程育种过程中都要进行筛选。例如,杂交育种过程中,为选育出符合要求的显性纯合子,要让具有显性性状的个体连续自交,直到不再发生性状分离为止。杂交育种往往要经历很多代筛选才能获得所需要的类型。基因突变具有 High school biology genetics and breeding, genetic engineering, monoclonal antibody preparation, separation of microorganisms and other teaching content involves the screening of the college entrance examination in recent years often use it as a proposition material, are now briefly summarized the screening problems and combined with the following example analysis. I. Screening in Genetics and Breeding In order to obtain the desired type of organism, screening should be carried out in crossbreeding, mutagenesis, haploid breeding and genetic engineering breeding. For example, during the breeding process, in order to breed the qualified dominant homozygote, individuals with dominant traits should be selfed continuously until no trait separation occurs. Hybrid breeding often go through many generations of screening to get the type you want. Gene mutation has