In this video, we're going to continue to talk about animal viruses and animal virus infections by focusing specifically on DNA virus synthesis and replication. And so most DNA viruses that contain D. N. A. As their genome will replicate inside of the host cell's cytoplasm and it will replicate inside of the host cell's cytoplasm using the host cell's components and hijacking the host cells cellular machinery. However, most DNA viruses will actually encode their own viral DNA preliminary race and the viral DNA prelim arrays allows the viral DNA genome to replicate even when the host cell is not replicating. Now, moving forward in our course, we're going to talk more details about the synthesis and replication of double stranded DNA viruses. And then later we'll talk about the synthesis and replication of single stranded DNA viruses. And so I'll see you all in our next video.

in this video we're going to talk more details about the synthesis and replication specifically of double stranded DNA viruses or Ds. DNA viruses. And so double stranded DNA virus replication and expression actually follows the same steps as the central dogma of biology as we talked about it in our previous lesson videos. And so that makes a double stranded DNA virus synthesis and replication much easier to understand because we kind of already talked about this in our previous lesson videos. And so recall that the complementary strands of double stranded DNA are referred to as the plus coding strand and the minus template strand. And so we referred to the double stranded DNA molecule as a plus minus D. S. D. N. A. Where again the plus strand indicates that there is a coding strand and the minus strand indicates that there is a template strand in this double stranded DNA molecule. And so of course this double stranded DNA molecule we know it's going to follow the same steps of the central dogma of biology. And so transcription is going to be able to produce the messenger RNA. And recall that the messenger RNA A. Is the same exact thing as plus S. S. R. N. A. Or plus single stranded RNA. And it is plus because it is encoding messages. And so this M. R. N. A. Or S. S. S. R. N. A. Or S. S. RNA. That's made via transcription is then gonna be translated to make viral proteins. And so if we take a look at our image down below, which you'll notice is on the far left hand side, we're showing you the double stranded DNA virus genome. And so it's a plus minus double stranded DNA. And so when this double stranded viral genome is uh in the cell's cytoplasm uh the cells uh machinery is going to allow for protein synthesis which is this entire top pathway. And that's going to occur via transcription where the double stranded DNA is used as a template for building plus S. S. RNA. Or messenger RNA. And of course this plus S. RNA. Or messenger RNA is going to encode. The message is uh allowing for translation to occur and translation will build the viral proteins. Now these viral proteins can also include viral DNA polymerase races that will allow for genome replication of the double stranded DNA virus genome. And so genome replication is always going to entail recreating the original viral genome. And so the viral genome must be recreated. And so of course it's going to lead to even more plus minus double stranded DNA. And so basically the result here is that it's replicating the original genome and it's synthesizing viral proteins. And so once these viral proteins have been synthesized and the original genome has been replicated, then it can move on to the fourth stage of an animal virus infection which is going to be assembly of these components. And we'll get to talk more about the assembly later in our course. But for now this year concludes our brief lesson on the synthesis and replication of double stranded DNA, or DS. DNA viruses. And we'll be able to get some practice applying these concepts. And then we'll talk about the synthesis and replication of single stranded DNA viruses. So I'll see you all in our next video.

in this video, we're going to talk more details about the synthesis and replication of single stranded DNA viruses or S. S. DNA viruses. And so the good thing is is that the replication of single stranded DNA viruses is actually quite similar to the synthesis and replication of double stranded DNA viruses. And really there's only just the addition of an extra step. And so ultimately what happens is that single stranded DNA viruses or s. S. DNA viruses are going to have a single stranded DNA genome. Either a plus single stranded D. N. A. Of a coding strand or a minus single stranded DNA. Of a template strand. And so regardless of its plus or minus, this single stranded DNA is going to be converted to a plus minus double stranded DNA or D. S. D. N. A. And then at that point, once the double stranded DNA molecule has been generated, it is going to be very similar to the synthesis and replication that we saw with double stranded DNA viruses. And so what that means is that this double stranded DNA can be transcribed to form the messenger RNA or the plus S. S. R. N. A. Which of course can go on to be translated to make viral proteins. And this double stranded DNA molecule can also be used to replicate the original genome. And so it is going to be used to replicate this single stranded DNA genome. And so if we take a look at our image down below, we can get a better understanding of the synthesis and replication of single stranded DNA viruses. And so notice on the far left over here that we're showing you the original genome of the virus as it enters into the cell is going to be a single stranded or an S. S. D. N. A molecule. Now notice here we're indicating that it is a plus S. S. DNA molecule but it could also be a minus S. S. DNA molecule. Now regardless if it is a plus or minus single stranded DNA molecule, it is going to be converted to a double stranded DNA molecule, a plus minus double stranded DNA molecule. And then once the plus minus double stranded DNA molecule has been generated then synthesis and replication is going to be very similar to what we saw with double stranded DNA viruses. And so this double stranded DNA can be used as a template for transcription to build the plus S. S. R. N. A. Or the messenger RNA. And of course we know that the messenger RNA can be directly translated to form these viral proteins and that includes the formation of viral enzymes which can be used in genome replication. And genome replication is always going to replicate the original genome as it entered into the south. And so what you'll see is that it is going to be Plus S. S. D. N. A. That is going to be replicated here. And so once again uh here in this image we're showing you plus S. S. D. N. A. But it could also be minus S. S. D. N. A. And uh the of course it's going to regenerate minus S. S. DNA if that were the case. But ultimately, once these viral proteins have been synthesized and the original viral genome has been replicated, these components can then assemble with each other, which is the next stage of an animal virus infection that we'll get to talk more about later in our course. But for now, this year concludes our brief lesson on the synthesis and replication of single stranded DNA viruses or S. S. DNA viruses. And we'll be able to get some practice applying these concepts as we move forward in our course. So I'll see you all in our next video.