Bacterial colonies in DNA cloning?

sameeralord

If there is some identical bacteria in petri dish and you insert plasmids containing different DNA fragemnts. When bacteria that takes it up grows, do they grow in separate colonies. I mean does all bacteria that took plasmid A grow into one colony, and all bacteria that got plasmid B into one colony. But at the beginning all the bacteria was identical so why do they grow into separate colonies. Basically in other words I don't understand how bacterial colonies work. Thanks

Ygggdrasil

The way you isolate bacterial colonies is by diluting the bacteria down to a low concentration and then spreading them out on a petri dish. This way, individual bacterial cells are spread out throughout the petri dish and relatively far away from their neighbors. As the bacteria divide, the progeny of each individual bacteria are spatially separated from each other and form colonies on the plate.

sameeralord

Thanks Does this mean, let's say some bacteria took plasmid A and some took plasmid B. Then dilute as you said. Then can there be like 2 or more colonies contaning plasmid A or B.

Ygggdrasil

Yes. The number of colonies with the plasmid will reflect the number of bacteria that took up the plasmid.