The nucleus is not the only source of DNA, besides it, DNA is also found in the mitochondria of all eukaryotic cells, as well as in the chloroplasts of plant cells and such DNA is called extrachromosomal DNA.
The DNA from the mitochondria (mtDNA) and chloroplasts are small and circular, which are similar to the prokaryotic DNA.
mtDNA contains its own genes that encode proteins that are part of the electron transport chain.
Chloroplast DNA encodes for the components of the photosynthetic pathway.
