Nuclear DNA is found within the nucleus of our cells. It is linear in shape and it makes up 99.9% of the total DNA in our body.
Within the cell, the Nuclear DNA is packaged up into structures called chromosomes. Humans have 46 chromosomes per cell which are arranged in pairs (23 of these come from your mother and 23 from your father). These chromosomes contain between 20,000-25,000 genes.
Nuclear DNA (and the genes that it holds) are responsible for providing the basis for how human bodies are built and work, as well as determining all our characteristics.
This is a special circular type of DNA that is only found within the mitochondria themselves and it makes up only 0.1% of the total DNA in our bodies.
Mitochondrial DNA contains only 37 genes, all of which are essential for normal mitochondrial function (13 of these genes provide instructions for making enzymes involved in the Electron Transport Chain and the remaining genes provide instructions for making molecules which help put proteins together.)
Mitochondrial DNA is inherited only from your mother (as the fathers mDNA is destroyed during fertilization). Humans contain between 100-1000's copies of mitochondrial DNA per cell.