In this video, we're going to begin our lesson on horizontal gene transfer. Recall from our previous lesson videos that horizontal gene transfer occurs between two organisms that are not direct descendants of one another. These two organisms are going to be transferring genes between each other. Horizontal gene transfer allows cells to quickly acquire new traits and it also drives genetic diversity among organisms. Now there are three known mechanisms of horizontal gene transfer in bacteria.
Notice that we have those three mechanisms numbered down below: 1, 2, and 3. The first mechanism is transformation. The second mechanism is transduction. The third mechanism of horizontal gene transfer is conjugation. What you'll notice is that these numbers correspond with the numbers in our image.
For the first mechanism of horizontal gene transfer, we have transformation. Transformation is horizontal gene transfer via the uptake of free or naked DNA in the environment by a cell. If we take a look at our image down below at number 1 on the left-hand side, notice it's showing you transformation. Transformation occurs when a cell brings in free or naked DNA from the environment. When the free or naked DNA is brought into the cell and incorporated into the cell, we refer to this as transformation.
Later in our course, we'll be able to talk more about transformation. Transduction is, again, going to be a form of horizontal gene transfer. It occurs between cells and is mediated specifically by a bacteriophage virus. A bacteriophage is a specific type of virus that infects bacteria. If we take a look at number 2 down below, notice that this is showing us transduction, which is not to be confused with transformation because they sound similar, but they are different.
It is showing you a bacteriophage or just a phage for short. The bacteriophage is responsible for transferring DNA into the cell. You can see that donor cell DNA is being transferred by the bacteriophage, and the recipient can receive that DNA. Again, we'll get to talk more about transduction later in our course. This is just the introduction to it.
The third and final mechanism of horizontal gene transfer is conjugation. This refers to the direct horizontal DNA transfer between cells during direct cell-to-cell contact. Notice that the final image over here is focusing on conjugation. We have two neighboring cells and they end up forming direct cell-to-cell contact where DNA and genes can be transferred from one organism over to a neighboring organism. Notice that the green molecule originally was not in this cell on the right, but now at the end, both cells have the green molecule.
This is an example of conjugation, the transfer of genes via direct cell-to-cell contact. Again we'll be able to talk more about conjugation later in our course. This is just the introduction. You can see that this is really our map of our lesson on horizontal gene transfer and moving forward we'll get to talk more about each of these mechanisms in more detail. Starting with transformation, then we'll move on to transduction, and last but not least, we'll move on to conjugation.
This concludes our brief intro to horizontal gene transfer, and I'll see you all in our next video.