Feeling frayed at the edges?

That's because you probably are. This is a representation of a pair of chromosomes. Like all of them, they have to be replicated thousands of times during your lifetime. Inevitably the bits at the ends become frayed. Evolution has kindly allowed some leeway whereby the ends don't have any meaningful function, and can be eroded without causing you heavy grief.

[Think of photocopying the same bundle of papers over and over again. The first and last pages would become crumpled and jam everything up, so you put a few blank pages at the beginning and end to protect the important pages.]

Eventually however even this protection wears down, replication gets less and less accurate, our cells malfunction, disease may occur. This is, I suppose, our built-in obsolescence.

More here telomeres.