ELi5: what causes genes to mutate?
In: Biology
Sometimes there’s a specific thing that causes genetic mutations, like exposure to ionizing radiation or other environmental exposure to things like toxins, but most of the time it’s just random chance. These random mutations occur when DNA is making copies of itself and sometimes it just makes a mistake. Sort of like how if you were to type out a really long essay, you’re almost certain to make a couple of typos that you didn’t notice. There’s no rhyme or reason why you made *those specific* typos, and if you typed the same essay again, you’d probably make different ones.
[https://youtu.be/X_tYrnv_o6A?t=75](https://youtu.be/X_tYrnv_o6A?t=75)
This is a simulation of how DNA is copied. This is one protein machine copying 1 strand. There are countless machines like this, copying DNA all the time. When you are copying billions of things, billions of times, over billions of cells, you are going to get some errors. Nothing is perfect. Even those protein machines break down.
The enzymes that make copies of DNA rarely make mistakes. But like 0.00001% (or something) of the time they insert the wrong base into the new DNA copy. Since genomes can be hundreds of millions of base pairs long, those mistakes happen all the time.
Even so, it’s really rare that the mutation actually affects a gene, since genes only make up about 2% of the total genome. And even if it does, it rarely has any affect on the product of the gene. But once in a really really long while, a beneficial mutation to a gene gives the organism some kind of advantage compared to other organisms.
Mutagens are things (like sunlight or idk, nicotine?) that increase the number of mistakes made by DNA-copying enzymes. If mutations have any effect on the organism, it’s almost always a bad thing. Beneficial mutations are incredibly rare.
Latest Answers