Genetic recombination in bacteria can occur in a few different ways. This video lesson will explore those methods, providing you with good understanding of how genetic information may be exchanged between these types of cells.
What Is Recombination?
Have you ever gone to a clothing swap? These are fun events where you take old clothes that you don’t want anymore and hopefully pick up some new clothes from someone else’s ‘old’ pile that they brought with them. It’s a great way to add variety to your wardrobe by creating new ways to mix and match your outfits.Bacteria don’t have clothing swaps, but they do have ‘DNA swaps’ where something similar happens. Genetic recombination is when genes from two different sources are combined to form a new genetic combination. Like swapping a shirt with your friend, genetic information can be swapped between bacteria.
This occurs for a few different reasons. For example, it creates genetic diversity in a population of bacteria, much like genetic mutations do for other organisms. What’s better about recombination though, is that this process is less likely to cause harm to a gene’s function than a mutation and can even lead to new functions and processes for the bacteria.
There are three main ways that genetic recombination occurs in bacteria, the first of which is called transformation. This is when a piece of donor DNA is taken up by a recipient bacterium. Imagine that you brought nothing to the clothing swap but still went home with a new shirt.
That’s not really a ‘swap’ per se, but new DNA is taken up into the recipient bacterium cell and incorporated into its chromosome.The donor DNA fragment is called a plasmid, and this method of recombination is useful for a number of different applications. Sometimes, scientists can determine the effects of different DNA segments and create ‘designer’ bacteria. For example, a protein harvested from bacteria that underwent transformation was used to give the jeans you picked up at the swap that ‘stone-washed’ look.
The second method of genetic recombination in bacteria is called transduction. This is when DNA is transferred between bacteria through viruses.
It’s true – even bacteria can catch a cold! Here’s how it works: when a virus infects a bacterium it inserts its DNA, and in turn, uses the bacterium to reproduce that DNA. Some of the virus’ genetic material might get mixed up with the DNA of its host, so when the virus is done using the bacterium, and the virus’ DNA is released from its host, some of the bacterial DNA can end up tagging along.Eventually, the host cell will rupture from this process, releasing all of that newly replicated viral DNA out into the world. And, if some of the host DNA is hitchhiking, it will go right along with it. This is pretty sneaky, like mixing your clothes into your friend’s ‘take-home’ pile at the swap, hoping they didn’t notice that you threw in a few extras that they may not have wanted.
Bacteria don’t actually have sex, but if they did it might look like our third and final method, conjugation. This is when genetic information is exchanged through physical contact between two cells.
Two bacteria lie next to each other and, over time, genetic material is slowly passed from one bacterium to the other.Here’s the trick though – the donor has to have something called an F-plasmid and the recipient has to lack it. From the F-plasmid, the donor bacterium transfers a single DNA strand to the recipient, which is then copied by the recipient and incorporated into its own DNA. Voila! A new genetic combination. While this works for bacteria, I’m not sure that lying on the ground next to my friend is the easiest way to swap clothes. But hey, maybe it’s time to try something new!
There are lots of ways to exchange genetic information, but if you’re a bacterium you’re likely going to employ genetic recombination. This is when genes from two different sources are combined to form a new genetic combination.
This may occur through transformation, when a piece of donor DNA is taken up by a recipient bacterium; transduction, when DNA is transferred between bacteria through viruses; or conjugation, when genetic information is exchanged through physical contact between two cells. In all three of these processes, genetic information from one source is combined with that of a recipient cell, and a new genetic combination is created from the two.