QUESTION: Morphological structures (e.g. bones, etc.) are good for comparing evolutionary relatedness of similar organisms, like humans to monkeys or birds. But we generally need to use molecular targets (gene sequences) to compare very different organism

QUESTION: Morphological structures (e.g. bones, etc.) are good for comparing evolutionary relatedness of similar organisms, like humans to monkeys or birds. But we generally need to use molecular targets (gene sequences) to compare very different organisms, like humans and bacteria. What is a good example of a specific gene you could use to compare ANY living organism - there are several genes that are conserved (shared) in all known life. ...And I mean identify a SPECIFIC gene and give reason(s) why it is a good choice!