What are the exceptions to the general rule that DNA is the genetic material in all organisms? What evidence supports these exceptions?

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Hi everyone. Welcome back. Let's look at our next question. Which of the following organisms does not have DNA as its genetic material and were given four answer choices that are four different types of viruses. So let's just work our way through them. Choice A is bacteriophages. Bacteriophages are those viruses that infect bacteria very very very prevalent in the world. They can use D. N. A. Or RNA for their genomes. So that's a little bit tricky. But since our question says does not have DNA as the genetic material we can go ahead and eliminate this. Since it does bacteriophages can use DNA for their genomes. Then we have choice B papilloma viruses. Papilloma viruses are D. N. A viruses so they are not our correct answer. Since they do use G. D. N. A. For their genome papilloma viruses. Um Maybe the most famous one is HPV. Um In certain strains of HPV they can become cause cancerous tumors. Um They also can cause benign small tumors or warts or be asymptomatic. Um Now we move on to choice. See retro viruses and retroviruses are definitely our answer because the characteristic of retroviruses is that they use R. N. A. For their genetic material. Um Retrovirus is super super common caused tons of disease is probably the most infamous ones these days. Of course Covid 19 is a retrovirus HIV. Another notorious retrovirus but things like polio measles, mumps the common cold influenza. All those are retroviruses. And the reason there are so many is that by using RNA as their genome. They can mutate very very very quickly. Um And that allows them to evade our immune system very easily. Also makes it difficult to design vaccines for them. Um You can remember retroviruses of course you've got R. And R. RNA retroviruses. Also that retro um prefix implies sort of backwards. So I'm gonna start with RNA once they invade the host cell the host cell um creates D. N. A. From the RNA genome of the virus then that DNA gets incorporated into the host cell genome but they go backwards in storing their genetic material in RNA. Finally our last choices answer. D. Herpes viruses. Um These are also D. N. A viruses so we can eliminate them as our answer. And of course these do cause herpes. They also cause chickenpox and shingles, Epstein barr virus mono. Other things like that. But D. N. A viruses. So not our answer. So which of the following organisms does not have DNA as its genetic material. And the answer is choice C retroviruses. You in the next video

What are the exceptions to the general rule that DNA is the genetic material in all organisms? What evidence supports these exceptions?

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Key Concepts

DNA as the Genetic Material

RNA as Genetic Material in Some Viruses

Experimental Evidence Supporting RNA as Genetic Material