Virus

Real World Example

Imagine you have a locked smartphone but no charger, so you need to find a compatible charger to power it up and use it. Similarly, a virus is like this smartphone; it can't do much on its own and needs to find a suitable host cell to "charge" or replicate itself. Just as the smartphone relies on a charger to function, the virus depends on infecting a living cell to reproduce, using its protein coat to access the cell's machinery and replicate its DNA or RNA.