Question

How does a universal genetic code relate to the hypotheses about the origin of life on Earth?

Answer 1

All organisms on earth have one genetic code (except
mitochondrias i think). The
universal genetic code is prooof that all organisms
(prokaryotes and eukaryotes) evolved from one common ancestor,
because otherwise organisms would have different genetic codes.....

Answer 2

That's right - just thought I'd say something about the mitochondria you mentioned. They have the same genetic code as other cells in that their nucleic acids are formed with combinations of A, T, C, and G. In fact, mitochondria are thought to have arisen when prokaryotes infiltrated eukaryotic cells and formed a symbiotic relationship with them. In humans, mitochondrial DNA is inherited from the mother and is different from nuclear DNA. It overlaps in coding for some proteins, but notably contains genes for tRNA and mitochondrial enzymes (e.g. ones involved in the electron transport chain). Mitochondria cannot exist on their own as they need enzymes produced by the nuclear DNA to transcribe, translate, and regulate their own genes.

In short, yes, even mitochondria share the universal genetic code.

Answer 3

for exceptions you might want to look at http://www2.oakland.edu/biology/chaudhry/pics/Chapter7.pdf