Humans have 46 chromosomes in their DNA; an extra pair would mean they have Down Syndrome. 

She has 50 chromosomes. 46 of them construct her human characteristics while 4 of them contains high levels of Beryllium, Gold, Titanium and a special chromosome that encourages mitosis; thus she is indistructable. She is a weapon.

Mitosis occurs slowly in humans hence why healing wounds are slow.

Since mitosis happens in her faster than the normal pace, she heals. She can never break.

Oh, and humans have a respiratory muscle.

She does not.

She is the Impossible.

I know I should be updating 'Crossroad' instead of creating a new story, but this plot has been lingering in my mind for quite a while now and it bugged me so much that I had to release it. 

*I do not specialise in Biology! There will be a heavy mixture of fact and fiction in some of my explanations. The ratio between the two will not always be on par! Please cope with the heavily fictionalised fragments; I manipulated Science in order to form what I think is fit to explain whatever I may be during that time, but other than that reason I did not manipulate Science to prove anything.