Medical Genetics 1. Mitochondrial dna Mitochondria have some of their own dNa, ribosomes and can make many of their own proteins. The dNa is circular and lies in the matrix. in punctate structures called nucleoids". Each nucleoid may contain 4-5 copies of the mitochondrial DNa (mtDNA)Medical Genetics 1. Mitochondrial DNA Mitochondria have some of their own DNA, ribosomes, and can make many of their own proteins. The DNA is circular and lies in the matrix.in punctate structures called "nucleoids". Each nucleoid may contain 4-5 copies of the mitochondrial DNA (mtDNA)