Given the state of knowledge at the time of the Avery, MacLeod, a...

Question

Given the state of knowledge at the time of the Avery, MacLeod, and McCarty experiment, why was it difficult for some scientists to accept that DNA is the carrier of genetic information?

Accepted Answer

Hi everyone here's our next question Before the 1940s what was believed to be the source of genetic material? Well we can go ahead and eliminate D. N. A. Which is choice A. Um even if we weren't sure the way the question is phrased since we now know the source of genetic materials D. N. A. We know that presumably before the 19 forties there was another idea and our answer here is actually choice C proteins. And the reason they were thought to be the source of genetic material is for two reasons. One um proteins are found in the nucleus in almost equal amounts to D. N. A. So you've got them in the right place where this genetic action goes on. And more importantly um proteins had more structural diversity. So scientists found it much more convincing to imagine a genetic language having 20 letters per se. So the 20 amino acids proteins versus D. N. A. With just its four bases so that more structural diversity equaling 20 will say letters In its alphabet. So as you can imagine if you're saying we need something that stores all the genetic information for every kind of living thing. Um you would imagine that something that has so much more diversity these 20 different amino acids um which seems like a much more likely candidate than something with just four base pairs. So proteins were believed to be the source of genetic material. Um RNA was looked at but of course same limitations as D. N. A. With its four bases and A T. P. Has no variation whatsoever. It's a single molecule. Um, There's no way to store material with it so we can eliminate choice D. So again, that's choice C proteins believed early on to be the source of genetic material. See you in the next video.

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Given the state of knowledge at the time of the Avery, MacLeod, and McCarty experiment, why was it difficult for some scientists to accept that DNA is the carrier of genetic information?