Recombinations that can lead to rearrangements of loci require transposable elements. Transposons and insertion sequences are not the only forms of DNA that qualify as transposable. Recombination arising from transposition using plasmid vectors is a major tool of the molecular biologist. You need to be familiar with plasmid nomenclature to be able to identify the following types: 1) Fertility-F-plasmids, which contain tra-genes making them capable of conjugation. This means that they can form a sex pilus enabling the exchange of bacterial genes. 2) Resistance-R-plasmids, which contain genes that can build a resistance against antibiotics or poisons. 3) Col-plasmids, which contain genes that code for proteins called colicines that can kill other bacteria. Plasmids contain their own origins of replication.

For the MCAT you also need to be familiar with the use of phages as vectors for recombinant DNA experiments including the lysogenic phages (Lambda and Mu).

Definitely take the time to get a good feel for this material with its confusing and overlapping nomenclature. This is at the heart of the MCAT'ís newly increased emphasis on genetics and molecular biology.