Kate: Welcome to the Sound of Science on WNIJ. I’m Kate Powers from NIU STEM Outreach. Today we have a question from Marcella. She wants to know what percentage of our genes come from our parents. Marcella, it depends on who bought the denim pants and how many pairs you already have.
Sam: That’s not what she had in mind. She wants to know about DNA, not dungarees. Obviously we get 50 percent of our genes from our biological mothers and 50 percent from our biological fathers.
Kate: And 8 percent from viruses.
Sam: Viruses?
Kate: Viruses. These weird quasi-alive chunks of proteins hijack cells in order to produce and distribute copies of themselves. Viruses include the common cold, the flu, measles, zika, and HIV. They jump in line when the cells replicate DNA, getting a free ride and a free copy. For some types of viruses, this means they have an army to break loose and attack other cells.
Sam: And what about the others? They just quietly lurk in the cell waiting to strike?
Kate: Yeah, pretty much. They let the cell reproduce entirely.
Sam: Don’t we have systems in place to block this?
Kate: Yes, there are proteins that spot foreign DNA and kinda lock them in place. The viruses still replicate, but not enough to wreak havoc upon our bodies. They eventually become part of us as we pass our newly modified DNA from parent to child to grandchild. It takes a long time, but eventually their DNA spreads among the population, adding to the species’ genome.
Sam: They get a free ride for the rest of time? They don’t contribute to humanity?
Kate: Scientists and researchers are still working out the details, but it looks like these viruses -- called endogenous viruses -- have helped in a lot of ways. For example, viruses are quick to mutate, so they’ve helped in the creation of different types of cells.
Sam: They’re also good at hiding from our immune system. Does that benefit us in any way?
Kate: Oh, incredibly so! Evidence shows that endogenous viruses helped in the evolution of the placenta in mammals. A fetus can look like a foreign invader to a mother’s body. Endogenous virus DNA hides the fetus cells from the mom’s immune system, so it can grow and develop.
Sam: So that 8 percent we get from viruses is a pretty important 8 percent! Keep sending us your questions by emailing STEMOutreach@niu.edu.
Kate: This has been the Sound of Science on WNIJ
Sam: Where you learn something new everyday.
