In this video, we're going to begin our lesson on genome variability. Scientists have discovered over the years that different strains of a single species can have some genome variability. In other words, different strains of a single species can have some differences in their genome or their DNA sequences. Now, in order to better understand this genome variability, we need to introduce these two terms that you see down below. The genome of all strains within a species is composed of 2 elements. The first element is called the pangenome, and the second element is called the conserved genome, or in other words, the core genome.
The pangenome refers to all of the genes in every strain of the species. This includes the genes that are unique across different strains as well as the genes that are consistent across different strains. The pangenome refers to all of the genes in every strain of a species. On the other hand, the conserved genome or the core genome does not refer to all of the genes. Instead, it only refers to the genes that are conserved, shared, or consistent across every strain of that species.
In order to better understand these two terms, we have this image down below. This image represents the pangenome of a specific species that has 3 different strains. Strain number 1 is represented by this green circle. Strain number 2 is represented by a blue circle. And then strain number 3 is represented by a pink circle. These are 3 different strains of the same species. When we're collectively looking at all of the genes in every strain of the species, we're looking at the pangenome. This here represents the pangenome; the genes of strain 1, strain 2, and strain 3.
The core genome, the conserved or core genome, only refers to the genes that are conserved, shared, or consistent. In this image, the core genome is represented right here within the shaded area because there's overlap between all three strains. This can be labeled as the conserved genes, otherwise known as the core genome. As we can see, the conserved genome is always going to be consistent across every strain of that species, but each strain will also have unique genes. This here concludes our brief introduction to genome variability.
As we move forward in our course, we're going to talk about some of the elements that contribute to genome variability. I'll see you all in our next video.