| Some bacteria exchange parts of their Instruction Books in a way that resembles sexual reproduction. This process, called conjugation, is very different from sexual reproduction. First of all, conjugation isn't reproduction; it produces no new organisms. Secondly, since it's not reproduction, conjugation acts on the bacteria involved, rather than their offspring. What conjugation does do is allow bacteria to quickly pass Instructions among themselves. | ||
| Conjugation happens like this: some bacteria have Instructions that allow them to form tubes that permit them to dock with other bacteria and send them the Instructions that build the tubes. The tube-building Instructions, taken together, are called the F-factor, and any bacteria that have the F-factor are called "male". (Even though this isn't sexual reproduction, the bacteria that starts with the F-factor is called male and the recipient is called female.) The F-factor is usually found in a plasmid. | The F-factor and its workers act much like transposons and transposases. | |
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If conjugation only copied the Instructions for conjugation, it
wouldn't be very useful. Sometimes, though, the F-factor plasmid
recombines with other plasmids in the bacterium or even with the whole
bacterial Instruction Book. In these cases, when the bacterium with
the F-factor conjugates with a female bacterium, it passes on a number
of other Instructions with the F-factor.
Conjugation takes much less energy and raw materials than either asexual or sexual reproduction. Since bacteria that can conjugate don't need to be mature in order to exchange Instructions, they can undergo genetic change much more rapidly than other organisms. This explains, for example, the ability of some bacteria to quickly develop resistance to new antibiotics. Some bacteria go even further to try to get new Instructions. If they bump into DNA, they'll import it and try to carry out the Instructions it specifies. While this gives them the opportunity to try out many new Instructions, not all of the Instructions they come across are good for them, and this sometimes kills the bacterium. No eukaryotes conjugate or pick up DNA from the outside world. Since they create new Instructions only through recombination, and pass them on only during reproduction, eukaryotes' Instruction Books change much more slowly than do bacteria's. |
Part Two: Copying the Book
Part Three: Improving the Book
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