Am I correct that the DNA does not determine the shape of the organism, but DNA just codes for proteins, which determines certain traits? In many experiments scientists inject the DNA of the glowing jellyfish that makes them glow into another organism, they now make the protein that glows but they do not turn into jellyfish.
DNA determines everything (if you include mitochondrial DNA, which is separate from the chromosomes in the nucleus, and if you exclude bacteria which have RNA instead of DNA). HOX genes are the ones that determine major body areas; some of them are similar in organisms as different as insects and humans.
An error in this kind of gene is how you get flies with legs where antennae should be, and that sort of thing.
In the jellyfish example they are not injecting ALL of the jellyfish's DNA, only the small strand that is related to the glowing.