5.1
Scientists can inactivate or knock out a gene in animals, commonly mice, to learn more about the function of the gene, usually by replacing it with a targeting vector, an engineered piece of DNA.
The targeting vector has sequences that are homologous, identical to the sequences before and after the gene. It usually also has a positive selection marker such as the gene for neomycin resistance NeoR in the middle and a negative selection marker like the gene for thymidine kinase TK at one end.
When introduced into embryonic stem cells it replaces the gene through homologous recombination which occurs naturally between stretches of DNA with similar sequences. Cells where the gene has been correctly replaced will contain the positive marker but not the negative one allowing them to be identified in culture. These cells are then inserted into a mouse embryo and implanted into the uterus of a female. The resulting mouse has a combination of normal cells and cells with the gene knocked out on one chromosome.
These mice are then bred to generate so-called knockout mice that are homozygous for the knockout in all cells.
유전자의 기능에 대해 더 배우기 위해 과학자들은 유전적으로 조작된 유전자제거(knock-out; 넉아웃) 동물을 만들어 유전자가 활성화되지 않거나 “넉아웃”되었을 때 어떤 일이 일어나는지 관찰할 수 있습니다. 유전자제거 쥐는 특히 암, 파킨슨병, 그리고 당뇨병과 같은…