didnt they make doctor pulaski younger using a hair they found and the transporter one time? could they do that for anyone else? like keep a hair on file and make people young again when they start getting too old? could they use someone elses hair to make you look like the other person?
1) Contrary to the episode's premise, generally speaking, a person's DNA does not change as they age. Therefore, it's not very useful to keep a copy of one's DNA for age regression purposes. 2) Replacing a person's DNA would not have any effect on their appearance. Think about it. You'd only be exchanging DNA molecules, not the quantity, shape, arrangement, or health of the cells. 3) If a person's DNA did change as they aged, and if a person's DNA could be replaced with the transporter, what would happen to all the cells currently undergoing mitosis / DNA replication? I tend to think they would either die or become mutated (potentially cancerous).
To be sure, the episode doesn't really state that aging involves the alteration of the DNA. Rather, it states that an alteration of DNA brought about the aging-like effects in Pulaski, which is a very different thing. So the heroes knew for sure that her DNA had been altered, and that this was the cause of the eerily aging-like woes. They could only hope that removal of the cause would restore the original state. And for that purpose, cross-comparison between the current Pulaski and a sample of her former DNA would be very relevant. This is made clearer in the penultimate script (see TrekCore) than in the aired version, but the story logic still works for the aired version as well. So no instant youth. Just instant de-wrinkling and de-arthritising, things that Pulaski or even Crusher can do at their leisure without the transporter. (The transporter was only needed to stop the process that was causing the pseudo-aging in Pulaski, and only incidentally used for reversing the symptoms after that.) But at some point, age still gets you, even if you happen to be de-wrinkled. So most 24th century people don't bother with such treatments. Howzzat sound? Timo Saloniemi
I just always assumed that there's some "component" to DNA, RNA, or something else entirely that we don't know about yet that they do in the 24c. Or that could be the logic in the Trek Universe, and not necessairly ours. It does seem to suggest that it is possible to keep a transporter trace or a hair sample of your younger self and you should be able to then use the transporter as a "fountain of youth."