ELI5: Explain Like I'm 5

Heterocyst

A heterocyst is a special type of cell that lives in some types of bacteria. These bacteria are called cyanobacteria, and they are very important because they can turn sunlight into food through a process called photosynthesis.

Now, even though cyanobacteria can make their own food, they still need nitrogen to grow properly. Nitrogen is an important element that helps make things like proteins and DNA.

But here's the thing: the kind of nitrogen that cyanobacteria need isn't always available in their environment. That's where heterocysts come in.

Heterocysts are like little nitrogen factories. They are able to take nitrogen from the air and turn it into a form that cyanobacteria can use. This is really important, because it means that cyanobacteria can survive in places where other organisms can't, like in soil or in water.

But there's a catch: when heterocysts are working hard to convert nitrogen, they're not able to do photosynthesis as well. So, in order to make up for this, other cells in the cyanobacteria take over the job of making food for the whole group.

So, to sum it up: heterocysts are special cells in some bacteria that turn nitrogen from the air into a form that the bacteria can use. They're like tiny factories that help keep the whole group alive, even in places where food and nutrients are scarce.