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 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, and the third mechanism of horizontal gene transfer is conjugation. You'll notice that these numbers also correspond with the numbers in our image below.
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, where 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 going to be a form of horizontal gene transfer 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. While they sound similar, transduction is different from transformation. Here, a bacteriophage or phage is responsible for transferring DNA into the cell. You can see donor cell DNA being transferred by the bacteriophage, and then the recipient cell can receive that DNA. 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, referring to the direct horizontal DNA transfer between cells during direct cell-to-cell contact. Notice in the final image over here focusing on conjugation. You will see two neighboring cells 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 not in the cell on the right, is now in both cells at the end. This is an example of conjugation, the transfer of genes via direct cell-to-cell contact. We'll be able to talk more about conjugation later in our course. This is just the introduction.
This concludes our brief introduction to horizontal gene transfer, and I'll see you all in our next video.