Question 3
Why can a bacterium read a human gene and make the human protein?
The right answer is the one marked above.
Because the genetic code is essentially the same in all living things. A gene is a sequence of the same four bases wherever it sits, and a bacterium reads it the same way a human cell does.
That shared chemistry is what the whole technology rests on — and it is also strong evidence that all life on Earth has a common origin.