Gene duplication can lead to multi-gene families, which is a set of several similar genes formed through gene duplication. Sometimes these can be gene clusters, which are genes that are near each other on the chromosome and part of the same family. We have an example of a gene cluster here, showing us the formation; here we have this hybrid gene, and it's evolving, and we wind up with a 3-member gene family with 3 versions of this b gene. It's worth noting that sometimes in multi-gene families, the genes are not actually in close proximity and they can be quite far apart. That happens through other processes.
When talking about gene clusters, we cannot fail to mention the hox genes, which are a highly conserved gene family that determines the body plan of an embryo, and we're going to revisit this idea when we talk about development. For now, let's think about this as a gene cluster, and you can see here that all of the individual genes in this gene family help define the different parts of the embryo's body. These genes are highly conserved and they are used by many different types of organisms. Again, we will be revisiting this idea of Hox genes when we talk about development.
So, let's flip the page and talk about what all that non-coding DNA is for.