In mitochondria, the inner membrane space is filled with a matrix which contains dense granules along with ribosomes and mitochondrial DNA. The mitochondrial DNA is circular in nature. There number varies from 2-6. Besides DNA, a mitochondrion has RNA and its ribosomes also. Thus, a complete protein synthesizing machinery is present in mitochondria, which suggests the semi-autonomous nature of mitochondria. Dictyosome, lysosome and peroxisome do not have their own DNA.