Is a Gene Harmful or Helpful? Depends on the Context

Why do organisms have “bad” genes even after millions of years of evolution? Why do genes that are detrimental to an organism’s health – genes that linger but never quite disappear from a population – remain in an organism’s genome after generations? According to Science Daily, these so-called “harmful” genes may be helpful – in certain situations. Historically, the concept of antagonistic pleiotrophy – the idea that certain genes that could be beneficial in some situations and harmful in others – is often used to explain why genetic disorders still exist in human populations.

Previously, this theory was used to explain a few types of genes, such as those that control aging and those that may lead to cancer. However, scientists at the University of Michigan have discovered that antagonistic pleiotrophy can be very influential in an organism’s lifetime. A University of Michigan research team lead by Dr. George Zhang discovered that yeast, a single-celled eukaryotic organism, displayed “widespread antagonistic pleiotrophy”. Yeast is very important in global culture and economy – it is used for making bread and brewing lagers, among other things.

The experiment showed that yeast cells had a capability to activate certain genes based on their growing conditions. For his experiment, he used six different environments, one of which included ethanol. From his conclusions, Zhang and his colleagues learned that yeast was able to choose which genes to turn on to fit its specific environment.

This experiment is interesting because it shows that organisms are very adaptable. It also explains why organisms have “good” and “bad” genes. The idea that the environment can control what genes are expressed is a very powerful concept. It won’t be long until scientists learn more about antagonistic pleiotrophy in humans.