1. Explore

Living organisms can have many different kinds of mutations. Some mutations cause clear and serious changes, while others do not cause any noticeable effect at all. To understand this better, we can again use the house blueprint example. A random change in a carefully designed plan can lead to very different results (Alberts et al., 2015).

For instance, a small change might create a gap between a window and a wall, allowing cold air to enter the house. Another change could damage the plumbing system, making everyday life uncomfortable. In biology, similar small mutations can slightly affect how a protein works or how efficiently it is produced.

Sometimes, a large random change can cause serious problems. Removing a load-bearing wall from a house could cause the whole building to collapse. In the same way, some mutations strongly disrupt essential genes and can lead to diseases or developmental problems (Strachan & Read, 2018).

However, not all changes are harmful. Some mutations have no effect at all, such as replacing one roof tile with another identical one. In genetics, these are called neutral mutations. Very rarely, a mutation can even be beneficial. An example is lactose tolerance in humans—the ability of adults to digest milk—which became advantageous after the domestication of cattle (Griffiths et al., 2019).

The effect of a mutation mostly depends on:

• whether it changes a gene that codes for a protein or RNA,
• how important that gene is for the organism,
• and how strongly the gene is expressed (how much it is “turned on”).

Because genes interact in complex networks, even a small mutation can sometimes have wide effects, while other mutations remain unnoticed (National Human Genome Research Institute, 2023).