Biology
Mutations
Small errors in the genetic code can harm, do nothing, or create something new. They are the raw material of evolution.
The genetic code is like a long text that sits in every cell and holds the blueprint of the living thing. When this text is copied, tiny errors sometimes happen. Such a change in the genetic code is called a mutation. At first it sounds like a problem, yet it is also the source of all the variety of life.
An error in the blueprint
The genetic code, called DNA by scientists, is built from four building blocks that sit in a certain order. In a mutation a block gets swapped, drops out, or is added on top. Even a small change can alter the meaning of the text, just as a wrong letter changes a word.
Click a rung to change the left base.
Rule: A pairs with T, G pairs with C.
A T G → T A CCauses of mutations
Some mutations arise simply by chance when the genetic code is copied. Others are triggered, for example by strong sunlight, certain substances, or radioactive radiation. Such influences raise the number of errors during copying.
Harmful, neutral, or useful
A mutation can have three effects. Most often it is neutral and changes almost nothing, because it hits a spot that does not matter. Often it is harmful and disturbs the blueprint. Only rarely is it useful and gives the living thing an advantage. Which effect happens depends on which spot in the genetic code is hit.
The raw material of evolution
Without mutations there would be no variety and no change over time. Only a mutation in a cell, that is in an egg or sperm cell, gets passed on. An error in a skin cell stays there and never reaches the offspring. Useful mutations in germ cells, on the other hand, can spread over many generations. In this way random errors provide the material from which evolution shapes new traits.
Exercises
0 of 6 solvedTime to try it yourself. You can't break anything, every attempt counts.
What is a mutation?
Which effect does a mutation have only rarely?
How many different building blocks is the genetic code made of?
Match each kind of mutation to the change it makes to a building block.
A mutation can have three effects: harmful, neutral, useful. How many effects is that?
Useful mutations can be passed on. That is why mutations are the … of evolution.