Does our tiny organelles with their own DNA cause harm when something goes wrong during replication? If so what are the effects.
It’s called mutation. If the DNA is damaged in some way, be it radiation or bad devision, then those cells devide, and those cells devide, and you eventually have nine purple heads. If you’re young, the risk is high. If the mishap happens when you’re older, the bad cells won’t have time to devide much, and no harm done. But those damn babies…
Yes, mitochondria do have their own (very small) genomes, and mutations to genes in mitochondria can cause disease. For instance myoclonic epilepsy associated with ragged-red fibers is caused by a mutation in a mitochondrial gene, as are several other disorders. Most mitochondrial genes play roles in mitochondrial function, so all the disorders I’m aware of are a result of abnormal mitochondrial function. I’m not aware of any cancers caused by mitochondrial genes, but I didn’t do a really intensive search. Since mitochondria are passed almost exclusively from the mother, mitochondrial diseases have an unusual inheritance pattern where (generally speaking) all of the children of and affected woman will be affected, but non of the children of an affected male will be affected.