[Script Info]
Title: 
[Events]
Format: Layer, Start, End, Style, Name, MarginL, MarginR, MarginV, Effect, Text
Dialogue: 0,0:00:00.00,0:00:00.47,Default,,0000,0000,0000,,
Dialogue: 0,0:00:00.47,0:00:03.21,Default,,0000,0000,0000,,Considering that I have a cold\Nright now, I can't imagine a
Dialogue: 0,0:00:03.21,0:00:08.11,Default,,0000,0000,0000,,more appropriate topic to make\Na video on than a virus.
Dialogue: 0,0:00:08.11,0:00:09.93,Default,,0000,0000,0000,,And I didn't want to\Nmake it that thick.
Dialogue: 0,0:00:09.93,0:00:11.38,Default,,0000,0000,0000,,A virus, or viruses.
Dialogue: 0,0:00:11.38,0:00:14.76,Default,,0000,0000,0000,,
Dialogue: 0,0:00:14.76,0:00:19.08,Default,,0000,0000,0000,,And in my opinion, viruses are,\Non some level, the most
Dialogue: 0,0:00:19.08,0:00:21.45,Default,,0000,0000,0000,,fascinating thing in\Nall of biology.
Dialogue: 0,0:00:21.45,0:00:25.56,Default,,0000,0000,0000,,Because they really blur the\Nboundary between what is an
Dialogue: 0,0:00:25.56,0:00:27.44,Default,,0000,0000,0000,,inanimate object and\Nwhat is life?
Dialogue: 0,0:00:27.44,0:00:30.08,Default,,0000,0000,0000,,
Dialogue: 0,0:00:30.08,0:00:33.41,Default,,0000,0000,0000,,I mean if we look at ourselves,\Nor life as one of
Dialogue: 0,0:00:33.41,0:00:35.21,Default,,0000,0000,0000,,those things that you know\Nit when you see it.
Dialogue: 0,0:00:35.21,0:00:39.30,Default,,0000,0000,0000,,If you see something that,\Nit's born, it grows, it's
Dialogue: 0,0:00:39.30,0:00:40.46,Default,,0000,0000,0000,,constantly changing.
Dialogue: 0,0:00:40.46,0:00:41.51,Default,,0000,0000,0000,,Maybe it moves around.
Dialogue: 0,0:00:41.51,0:00:42.26,Default,,0000,0000,0000,,Maybe it doesn't.
Dialogue: 0,0:00:42.26,0:00:44.40,Default,,0000,0000,0000,,But it's metabolizing things\Naround itself.
Dialogue: 0,0:00:44.40,0:00:46.31,Default,,0000,0000,0000,,It reproduces and\Nthen it dies.
Dialogue: 0,0:00:46.31,0:00:48.30,Default,,0000,0000,0000,,You say, hey, that's\Nprobably life.
Dialogue: 0,0:00:48.30,0:00:50.96,Default,,0000,0000,0000,,And in this, we throw most\Nthings that we see-- or we
Dialogue: 0,0:00:50.96,0:00:52.82,Default,,0000,0000,0000,,throw in, us.
Dialogue: 0,0:00:52.82,0:00:55.36,Default,,0000,0000,0000,,We throw in bacteria.
Dialogue: 0,0:00:55.36,0:00:57.12,Default,,0000,0000,0000,,We throw in plants.
Dialogue: 0,0:00:57.12,0:01:00.83,Default,,0000,0000,0000,,I mean, I could-- I'm kind of\Nbutchering the taxonomy system
Dialogue: 0,0:01:00.83,0:01:03.28,Default,,0000,0000,0000,,here, but we tend to know\Nlife when we see it.
Dialogue: 0,0:01:03.28,0:01:07.48,Default,,0000,0000,0000,,But all viruses are, they're\Njust a bunch of genetic
Dialogue: 0,0:01:07.48,0:01:09.74,Default,,0000,0000,0000,,information inside\Nof a protein.
Dialogue: 0,0:01:09.74,0:01:11.23,Default,,0000,0000,0000,,Inside of a protein capsule.
Dialogue: 0,0:01:11.23,0:01:13.49,Default,,0000,0000,0000,,So let me draw.
Dialogue: 0,0:01:13.49,0:01:16.34,Default,,0000,0000,0000,,And the genetic information\Ncan come in any form.
Dialogue: 0,0:01:16.34,0:01:22.24,Default,,0000,0000,0000,,So it can be an RNA, it could\Nbe DNA, it could be
Dialogue: 0,0:01:22.24,0:01:24.67,Default,,0000,0000,0000,,single-stranded RNA,\Ndouble-stranded RNA.
Dialogue: 0,0:01:24.67,0:01:27.26,Default,,0000,0000,0000,,Sometimes for single stranded\Nthey'll write these two little
Dialogue: 0,0:01:27.26,0:01:29.25,Default,,0000,0000,0000,,S's in front of it.
Dialogue: 0,0:01:29.25,0:01:30.95,Default,,0000,0000,0000,,Let's say they are talking about\Ndouble stranded DNA,
Dialogue: 0,0:01:30.95,0:01:32.91,Default,,0000,0000,0000,,they'll put a ds\Nin front of it.
Dialogue: 0,0:01:32.91,0:01:35.33,Default,,0000,0000,0000,,But the general idea-- and\Nviruses can come in all of
Dialogue: 0,0:01:35.33,0:01:38.11,Default,,0000,0000,0000,,these forms-- is that they have\Nsome genetic information,
Dialogue: 0,0:01:38.11,0:01:40.53,Default,,0000,0000,0000,,some chain of nucleic acids.
Dialogue: 0,0:01:40.53,0:01:43.73,Default,,0000,0000,0000,,Either as single or double\Nstranded RNA or single or
Dialogue: 0,0:01:43.73,0:01:44.56,Default,,0000,0000,0000,,double stranded DNA.
Dialogue: 0,0:01:44.56,0:01:47.97,Default,,0000,0000,0000,,And it's just contained inside\Nsome type of protein
Dialogue: 0,0:01:47.97,0:01:49.88,Default,,0000,0000,0000,,structure, which is\Ncalled the capsid.
Dialogue: 0,0:01:49.88,0:01:53.24,Default,,0000,0000,0000,,And kind of the classic\Ndrawing is kind of an
Dialogue: 0,0:01:53.24,0:01:56.65,Default,,0000,0000,0000,,icosahedron type\Nlooking thing.
Dialogue: 0,0:01:56.65,0:01:58.20,Default,,0000,0000,0000,,Let me see if I can\Ndo justice to it.
Dialogue: 0,0:01:58.20,0:02:00.61,Default,,0000,0000,0000,,It looks something like this.
Dialogue: 0,0:02:00.61,0:02:02.80,Default,,0000,0000,0000,,And not all viruses have to\Nlook exactly like this.
Dialogue: 0,0:02:02.80,0:02:05.16,Default,,0000,0000,0000,,There's thousands of\Ntypes of viruses.
Dialogue: 0,0:02:05.16,0:02:06.85,Default,,0000,0000,0000,,And we're really just scratching\Nthe surface and
Dialogue: 0,0:02:06.85,0:02:09.63,Default,,0000,0000,0000,,understanding even what viruses\Nare out there and all
Dialogue: 0,0:02:09.63,0:02:14.80,Default,,0000,0000,0000,,of the different ways that they\Ncan essentially replicate
Dialogue: 0,0:02:14.80,0:02:15.22,Default,,0000,0000,0000,,themselves.
Dialogue: 0,0:02:15.22,0:02:16.62,Default,,0000,0000,0000,,We'll talk more about\Nthat in the future.
Dialogue: 0,0:02:16.62,0:02:19.11,Default,,0000,0000,0000,,And I would suspect that pretty\Nmuch any possible way
Dialogue: 0,0:02:19.11,0:02:21.53,Default,,0000,0000,0000,,of replication probably\Ndoes somehow exist
Dialogue: 0,0:02:21.53,0:02:22.75,Default,,0000,0000,0000,,in the virus world.
Dialogue: 0,0:02:22.75,0:02:25.26,Default,,0000,0000,0000,,But they really are just these\Nproteins, these protein
Dialogue: 0,0:02:25.26,0:02:27.45,Default,,0000,0000,0000,,capsids, are just made up\Nof a bunch of little
Dialogue: 0,0:02:27.45,0:02:29.07,Default,,0000,0000,0000,,proteins put together.
Dialogue: 0,0:02:29.07,0:02:31.25,Default,,0000,0000,0000,,And inside they have some\Ngenetic material, which might
Dialogue: 0,0:02:31.25,0:02:33.70,Default,,0000,0000,0000,,be DNA or it might be RNA.
Dialogue: 0,0:02:33.70,0:02:35.87,Default,,0000,0000,0000,,So let me draw their\Ngenetic material.
Dialogue: 0,0:02:35.87,0:02:38.42,Default,,0000,0000,0000,,The protein is not necessarily\Ntransparent, but if it was,
Dialogue: 0,0:02:38.42,0:02:42.96,Default,,0000,0000,0000,,you would see some genetic\Nmaterial inside of there.
Dialogue: 0,0:02:42.96,0:02:48.44,Default,,0000,0000,0000,,So the question is, is\Nthis thing life?
Dialogue: 0,0:02:48.44,0:02:49.58,Default,,0000,0000,0000,,It seems pretty inanimate.
Dialogue: 0,0:02:49.58,0:02:50.54,Default,,0000,0000,0000,,It doesn't grow.
Dialogue: 0,0:02:50.54,0:02:51.51,Default,,0000,0000,0000,,It doesn't change.
Dialogue: 0,0:02:51.51,0:02:53.20,Default,,0000,0000,0000,,It doesn't metabolize things.
Dialogue: 0,0:02:53.20,0:02:55.20,Default,,0000,0000,0000,,This thing, left to its\Nown devices, is just
Dialogue: 0,0:02:55.20,0:02:55.85,Default,,0000,0000,0000,,going to sit there.
Dialogue: 0,0:02:55.85,0:02:59.60,Default,,0000,0000,0000,,It's just going to sit there the\Nway a book on a table just
Dialogue: 0,0:02:59.60,0:03:00.69,Default,,0000,0000,0000,,sits there.
Dialogue: 0,0:03:00.69,0:03:02.28,Default,,0000,0000,0000,,It won't change anything.
Dialogue: 0,0:03:02.28,0:03:06.56,Default,,0000,0000,0000,,But what happens is,\Nthe debate arises.
Dialogue: 0,0:03:06.56,0:03:08.47,Default,,0000,0000,0000,,I mean you might say, hey Sal,\Nwhen you define it that way,
Dialogue: 0,0:03:08.47,0:03:10.69,Default,,0000,0000,0000,,just looks like a bunch of\Nmolecules put together.
Dialogue: 0,0:03:10.69,0:03:11.74,Default,,0000,0000,0000,,That isn't life.
Dialogue: 0,0:03:11.74,0:03:14.35,Default,,0000,0000,0000,,But it starts to seem like life\Nall of a sudden when it
Dialogue: 0,0:03:14.35,0:03:17.10,Default,,0000,0000,0000,,comes in contact with the\Nthings that we normally
Dialogue: 0,0:03:17.10,0:03:18.22,Default,,0000,0000,0000,,consider life.
Dialogue: 0,0:03:18.22,0:03:22.48,Default,,0000,0000,0000,,So what viruses do, the classic\Nexample is, a virus
Dialogue: 0,0:03:22.48,0:03:24.68,Default,,0000,0000,0000,,will attach itself to a cell.
Dialogue: 0,0:03:24.68,0:03:28.59,Default,,0000,0000,0000,,So let me draw this thing\Na little bit smaller.
Dialogue: 0,0:03:28.59,0:03:30.26,Default,,0000,0000,0000,,So let's say that this\Nis my virus.
Dialogue: 0,0:03:30.26,0:03:32.56,Default,,0000,0000,0000,,I'll draw it as a\Nlittle hexagon.
Dialogue: 0,0:03:32.56,0:03:34.98,Default,,0000,0000,0000,,And what it does is, it'll\Nattach itself to a cell.
Dialogue: 0,0:03:34.98,0:03:35.80,Default,,0000,0000,0000,,And it could be any\Ntype of cell.
Dialogue: 0,0:03:35.80,0:03:39.16,Default,,0000,0000,0000,,It could be a bacteria cell, it\Ncould be a plant cell, it
Dialogue: 0,0:03:39.16,0:03:41.19,Default,,0000,0000,0000,,could be a human cell.
Dialogue: 0,0:03:41.19,0:03:43.82,Default,,0000,0000,0000,,Let me draw the cell here.
Dialogue: 0,0:03:43.82,0:03:48.54,Default,,0000,0000,0000,,Cells are usually far larger\Nthan the virus.
Dialogue: 0,0:03:48.54,0:03:51.61,Default,,0000,0000,0000,,In the case of cells that have\Nsoft membranes, the virus
Dialogue: 0,0:03:51.61,0:03:53.85,Default,,0000,0000,0000,,figures out some way\Nto enter it.
Dialogue: 0,0:03:53.85,0:03:58.78,Default,,0000,0000,0000,,Sometimes it can essentially\Nfuse-- I don't want to
Dialogue: 0,0:03:58.78,0:04:01.39,Default,,0000,0000,0000,,complicate the issue-- but\Nsometimes viruses have their
Dialogue: 0,0:04:01.39,0:04:02.48,Default,,0000,0000,0000,,own little membranes.
Dialogue: 0,0:04:02.48,0:04:03.74,Default,,0000,0000,0000,,And we'll talk about\Nin a second where
Dialogue: 0,0:04:03.74,0:04:04.76,Default,,0000,0000,0000,,it gets their membranes.
Dialogue: 0,0:04:04.76,0:04:08.27,Default,,0000,0000,0000,,So a virus might have its\Nown membrane like that.
Dialogue: 0,0:04:08.27,0:04:10.52,Default,,0000,0000,0000,,That's around its capsid.
Dialogue: 0,0:04:10.52,0:04:13.47,Default,,0000,0000,0000,,And then these membranes\Nwill fuse.
Dialogue: 0,0:04:13.47,0:04:16.78,Default,,0000,0000,0000,,And then the virus will be able\Nto enter into the cell.
Dialogue: 0,0:04:16.78,0:04:18.00,Default,,0000,0000,0000,,Now, that's one method.
Dialogue: 0,0:04:18.00,0:04:19.67,Default,,0000,0000,0000,,And another method,\Nand they're seldom
Dialogue: 0,0:04:19.67,0:04:20.59,Default,,0000,0000,0000,,all the same way.
Dialogue: 0,0:04:20.59,0:04:24.02,Default,,0000,0000,0000,,But let's say another method\Nwould be, the virus
Dialogue: 0,0:04:24.02,0:04:26.91,Default,,0000,0000,0000,,convinces-- just based on some\Nprotein receptors on it, or
Dialogue: 0,0:04:26.91,0:04:29.81,Default,,0000,0000,0000,,protein receptors on the cells--\Nand obviously this has
Dialogue: 0,0:04:29.81,0:04:31.65,Default,,0000,0000,0000,,to be kind of a Trojan\Nhorse type of thing.
Dialogue: 0,0:04:31.65,0:04:33.60,Default,,0000,0000,0000,,The cell doesn't want viruses.
Dialogue: 0,0:04:33.60,0:04:36.39,Default,,0000,0000,0000,,So the virus has to somehow\Nconvince the cell that it's a
Dialogue: 0,0:04:36.39,0:04:38.05,Default,,0000,0000,0000,,non-foreign particle.
Dialogue: 0,0:04:38.05,0:04:41.77,Default,,0000,0000,0000,,We could do hundreds of videos\Non how viruses work and it's a
Dialogue: 0,0:04:41.77,0:04:43.43,Default,,0000,0000,0000,,continuing field of research.
Dialogue: 0,0:04:43.43,0:04:47.58,Default,,0000,0000,0000,,But sometimes you might have a\Nvirus that just gets consumed
Dialogue: 0,0:04:47.58,0:04:48.12,Default,,0000,0000,0000,,by the cell.
Dialogue: 0,0:04:48.12,0:04:49.93,Default,,0000,0000,0000,,Maybe the cell just thinks it's\Nsomething that it needs
Dialogue: 0,0:04:49.93,0:04:50.96,Default,,0000,0000,0000,,to consume.
Dialogue: 0,0:04:50.96,0:04:53.13,Default,,0000,0000,0000,,So the cell wraps around\Nit like this.
Dialogue: 0,0:04:53.13,0:04:56.78,Default,,0000,0000,0000,,
Dialogue: 0,0:04:56.78,0:04:58.93,Default,,0000,0000,0000,,And these sides will\Neventually merge.
Dialogue: 0,0:04:58.93,0:05:01.67,Default,,0000,0000,0000,,And then the cell and the\Nvirus will go into it.
Dialogue: 0,0:05:01.67,0:05:03.16,Default,,0000,0000,0000,,This is called endocytosis.
Dialogue: 0,0:05:03.16,0:05:04.02,Default,,0000,0000,0000,,I'll just talk about that.
Dialogue: 0,0:05:04.02,0:05:06.64,Default,,0000,0000,0000,,It just brings it into\Nits cytoplasm.
Dialogue: 0,0:05:06.64,0:05:11.02,Default,,0000,0000,0000,,It doesn't happen\Njust to viruses.
Dialogue: 0,0:05:11.02,0:05:12.89,Default,,0000,0000,0000,,But this is one mechanism\Nthat can enter.
Dialogue: 0,0:05:12.89,0:05:17.32,Default,,0000,0000,0000,,And then in cases where the cell\Nin question-- for example
Dialogue: 0,0:05:17.32,0:05:20.28,Default,,0000,0000,0000,,in the situation with bacteria--\Nif the cell has a
Dialogue: 0,0:05:20.28,0:05:25.52,Default,,0000,0000,0000,,very hard shell-- let me\Ndo it in a good color.
Dialogue: 0,0:05:25.52,0:05:29.04,Default,,0000,0000,0000,,So let's say that this is\Na bacteria right here.
Dialogue: 0,0:05:29.04,0:05:30.51,Default,,0000,0000,0000,,And it has a hard shell.
Dialogue: 0,0:05:30.51,0:05:32.83,Default,,0000,0000,0000,,The viruses don't even\Nenter the cell.
Dialogue: 0,0:05:32.83,0:05:36.44,Default,,0000,0000,0000,,They just hang out outside\Nof the cell like this.
Dialogue: 0,0:05:36.44,0:05:37.74,Default,,0000,0000,0000,,Not drawing to scale.
Dialogue: 0,0:05:37.74,0:05:40.69,Default,,0000,0000,0000,,And they actually inject\Ntheir genetic material.
Dialogue: 0,0:05:40.69,0:05:43.79,Default,,0000,0000,0000,,So there's obviously a huge--\Nthere's a wide variety of ways
Dialogue: 0,0:05:43.79,0:05:45.68,Default,,0000,0000,0000,,of how the viruses\Nget into cells.
Dialogue: 0,0:05:45.68,0:05:46.78,Default,,0000,0000,0000,,But that's beside the point.
Dialogue: 0,0:05:46.78,0:05:49.42,Default,,0000,0000,0000,,The interesting thing is that\Nthey do get into the cell.
Dialogue: 0,0:05:49.42,0:05:52.24,Default,,0000,0000,0000,,And once they do get into the\Ncell, they release their
Dialogue: 0,0:05:52.24,0:05:54.57,Default,,0000,0000,0000,,genetic material\Ninto the cell.
Dialogue: 0,0:05:54.57,0:05:56.97,Default,,0000,0000,0000,,So their genetic material\Nwill float around.
Dialogue: 0,0:05:56.97,0:06:01.39,Default,,0000,0000,0000,,If their genetic material is\Nalready in the form of RNA--
Dialogue: 0,0:06:01.39,0:06:05.70,Default,,0000,0000,0000,,and I could imagine almost every\Npossibility of different
Dialogue: 0,0:06:05.70,0:06:08.16,Default,,0000,0000,0000,,ways for viruses to work\Nprobably do exist in nature.
Dialogue: 0,0:06:08.16,0:06:09.40,Default,,0000,0000,0000,,We just haven't found them.
Dialogue: 0,0:06:09.40,0:06:11.63,Default,,0000,0000,0000,,But the ones that we've already\Nfound really do kind
Dialogue: 0,0:06:11.63,0:06:13.88,Default,,0000,0000,0000,,of do it in every\Npossible way.
Dialogue: 0,0:06:13.88,0:06:20.72,Default,,0000,0000,0000,,So if they have RNA, this RNA\Ncan immediately start being
Dialogue: 0,0:06:20.72,0:06:23.17,Default,,0000,0000,0000,,used to essentially-- let's\Nsay this is the
Dialogue: 0,0:06:23.17,0:06:25.54,Default,,0000,0000,0000,,nucleus of the cell.
Dialogue: 0,0:06:25.54,0:06:28.85,Default,,0000,0000,0000,,That's the nucleus of the cell\Nand it normally has the DNA in
Dialogue: 0,0:06:28.85,0:06:29.48,Default,,0000,0000,0000,,it like that.
Dialogue: 0,0:06:29.48,0:06:30.72,Default,,0000,0000,0000,,Maybe I'll do the DNA in\Na different color.
Dialogue: 0,0:06:30.72,0:06:37.26,Default,,0000,0000,0000,,But DNA gets transcribed\Ninto RNA, normally.
Dialogue: 0,0:06:37.26,0:06:39.94,Default,,0000,0000,0000,,So normally, the cell, this a\Nnormal working cell, the RNA
Dialogue: 0,0:06:39.94,0:06:43.54,Default,,0000,0000,0000,,exits the nucleus, it goes to\Nthe ribosomes, and then you
Dialogue: 0,0:06:43.54,0:06:46.69,Default,,0000,0000,0000,,have the RNA in conjunction with\Nthe tRNA and it produces
Dialogue: 0,0:06:46.69,0:06:49.26,Default,,0000,0000,0000,,these proteins.
Dialogue: 0,0:06:49.26,0:06:51.03,Default,,0000,0000,0000,,The RNA codes for different\Nproteins.
Dialogue: 0,0:06:51.03,0:06:53.67,Default,,0000,0000,0000,,And I talk about that in\Na different video.
Dialogue: 0,0:06:53.67,0:06:57.00,Default,,0000,0000,0000,,So these proteins get formed and\Neventually, they can form
Dialogue: 0,0:06:57.00,0:06:58.80,Default,,0000,0000,0000,,the different structures\Nin a cell.
Dialogue: 0,0:06:58.80,0:07:03.19,Default,,0000,0000,0000,,But what a virus does is it\Nhijacks this process here.
Dialogue: 0,0:07:03.19,0:07:04.49,Default,,0000,0000,0000,,Hijacks this mechanism.
Dialogue: 0,0:07:04.49,0:07:08.55,Default,,0000,0000,0000,,This RNA will essentially go and\Ndo what the cell's own RNA
Dialogue: 0,0:07:08.55,0:07:09.23,Default,,0000,0000,0000,,would have done.
Dialogue: 0,0:07:09.23,0:07:11.14,Default,,0000,0000,0000,,And it starts coding for\Nits own proteins.
Dialogue: 0,0:07:11.14,0:07:12.25,Default,,0000,0000,0000,,Obviously it's not\Ngoing to code for
Dialogue: 0,0:07:12.25,0:07:13.26,Default,,0000,0000,0000,,the same things there.
Dialogue: 0,0:07:13.26,0:07:15.79,Default,,0000,0000,0000,,And actually some of the first\Nproteins it codes for often
Dialogue: 0,0:07:15.79,0:07:19.67,Default,,0000,0000,0000,,start killing the DNA and the\NRNA that might otherwise
Dialogue: 0,0:07:19.67,0:07:20.38,Default,,0000,0000,0000,,compete with it.
Dialogue: 0,0:07:20.38,0:07:22.39,Default,,0000,0000,0000,,So it codes its own proteins.
Dialogue: 0,0:07:22.39,0:07:26.86,Default,,0000,0000,0000,,And then those proteins start\Nmaking more viral shells.
Dialogue: 0,0:07:26.86,0:07:31.52,Default,,0000,0000,0000,,So those proteins just start\Nconstructing more and more
Dialogue: 0,0:07:31.52,0:07:33.84,Default,,0000,0000,0000,,viral shells.
Dialogue: 0,0:07:33.84,0:07:36.00,Default,,0000,0000,0000,,At the same time, this\NRNA is replicating.
Dialogue: 0,0:07:36.00,0:07:39.73,Default,,0000,0000,0000,,It's using the cell's own\Nmechanisms. Left to its own
Dialogue: 0,0:07:39.73,0:07:40.82,Default,,0000,0000,0000,,devices it would\Njust sit there.
Dialogue: 0,0:07:40.82,0:07:43.80,Default,,0000,0000,0000,,But once it enters into a cell\Nit can use all of the nice
Dialogue: 0,0:07:43.80,0:07:47.00,Default,,0000,0000,0000,,machinery that a cell has around\Nto replicate itself.
Dialogue: 0,0:07:47.00,0:07:51.36,Default,,0000,0000,0000,,And it's kind of amazing, just\Nthe biochemistry of it.
Dialogue: 0,0:07:51.36,0:07:54.81,Default,,0000,0000,0000,,That these RNA molecules\Nthen find themselves
Dialogue: 0,0:07:54.81,0:07:57.47,Default,,0000,0000,0000,,back in these capsids.
Dialogue: 0,0:07:57.47,0:08:00.29,Default,,0000,0000,0000,,And then once there's enough\Nof these and the cell has
Dialogue: 0,0:08:00.29,0:08:05.62,Default,,0000,0000,0000,,essentially all of its resources\Nhave been depleted,
Dialogue: 0,0:08:05.62,0:08:09.99,Default,,0000,0000,0000,,the viruses, these individual\Nnew viruses that have
Dialogue: 0,0:08:09.99,0:08:15.41,Default,,0000,0000,0000,,replicated themselves using all\Nof the cell's mechanisms,
Dialogue: 0,0:08:15.41,0:08:17.37,Default,,0000,0000,0000,,will find some way\Nto exit the cell.
Dialogue: 0,0:08:17.37,0:08:20.86,Default,,0000,0000,0000,,The most-- I don't want to\Nsay, typical, because we
Dialogue: 0,0:08:20.86,0:08:23.11,Default,,0000,0000,0000,,haven't even discovered all the\Ndifferent types of viruses
Dialogue: 0,0:08:23.11,0:08:26.75,Default,,0000,0000,0000,,there are-- but one that's, I\Nguess, talked about the most,
Dialogue: 0,0:08:26.75,0:08:28.76,Default,,0000,0000,0000,,is when there's enough of\Nthese, they'll release
Dialogue: 0,0:08:28.76,0:08:30.88,Default,,0000,0000,0000,,proteins or they'll construct\Nproteins.
Dialogue: 0,0:08:30.88,0:08:32.39,Default,,0000,0000,0000,,Because they don't\Nmake their own.
Dialogue: 0,0:08:32.39,0:08:35.86,Default,,0000,0000,0000,,That essentially cause the cell\Nto either kill itself or
Dialogue: 0,0:08:35.86,0:08:37.14,Default,,0000,0000,0000,,its membrane to dissolve.
Dialogue: 0,0:08:37.14,0:08:39.26,Default,,0000,0000,0000,,So the membrane dissolves.
Dialogue: 0,0:08:39.26,0:08:41.48,Default,,0000,0000,0000,,And essentially the\Ncell lyses.
Dialogue: 0,0:08:41.48,0:08:42.41,Default,,0000,0000,0000,,Let me write that down.
Dialogue: 0,0:08:42.41,0:08:43.84,Default,,0000,0000,0000,,The cell lyses.
Dialogue: 0,0:08:43.84,0:08:46.11,Default,,0000,0000,0000,,And lyses just means that\Nthe cell's membrane just
Dialogue: 0,0:08:46.11,0:08:46.90,Default,,0000,0000,0000,,disappears.
Dialogue: 0,0:08:46.90,0:08:50.48,Default,,0000,0000,0000,,And then all of these guys can\Nemerge for themselves.
Dialogue: 0,0:08:50.48,0:08:53.47,Default,,0000,0000,0000,,Now I talked about before that\Nhave some of these guys, that
Dialogue: 0,0:08:53.47,0:08:54.75,Default,,0000,0000,0000,,they have their own membrane.
Dialogue: 0,0:08:54.75,0:08:56.71,Default,,0000,0000,0000,,So how did they get\Nthere, these
Dialogue: 0,0:08:56.71,0:08:58.40,Default,,0000,0000,0000,,kind of bilipid membranes?
Dialogue: 0,0:08:58.40,0:09:00.90,Default,,0000,0000,0000,,Well some of them, what they\Ndo is, once they replicate
Dialogue: 0,0:09:00.90,0:09:07.38,Default,,0000,0000,0000,,inside of a cell, they exit\Nmaybe not even killing-- they
Dialogue: 0,0:09:07.38,0:09:08.65,Default,,0000,0000,0000,,don't have to lyse.
Dialogue: 0,0:09:08.65,0:09:11.62,Default,,0000,0000,0000,,Everything I talk about, these\Nare specific ways that a virus
Dialogue: 0,0:09:11.62,0:09:12.15,Default,,0000,0000,0000,,might work.
Dialogue: 0,0:09:12.15,0:09:15.63,Default,,0000,0000,0000,,But viruses really kind of\Nexplore-- well different types
Dialogue: 0,0:09:15.63,0:09:17.62,Default,,0000,0000,0000,,of viruses do almost every\Ndifferent combination you
Dialogue: 0,0:09:17.62,0:09:22.61,Default,,0000,0000,0000,,could imagine of replicating\Nand coding for proteins and
Dialogue: 0,0:09:22.61,0:09:23.40,Default,,0000,0000,0000,,escaping from cells.
Dialogue: 0,0:09:23.40,0:09:24.72,Default,,0000,0000,0000,,Some of them just bud.
Dialogue: 0,0:09:24.72,0:09:26.56,Default,,0000,0000,0000,,And when they bud, they\Nessentially, you can kind of
Dialogue: 0,0:09:26.56,0:09:28.07,Default,,0000,0000,0000,,imagine that they push\Nagainst the cell
Dialogue: 0,0:09:28.07,0:09:29.67,Default,,0000,0000,0000,,wall, or the membrane.
Dialogue: 0,0:09:29.67,0:09:30.74,Default,,0000,0000,0000,,I shouldn't say cell wall.
Dialogue: 0,0:09:30.74,0:09:32.63,Default,,0000,0000,0000,,The cell's outer membrane.
Dialogue: 0,0:09:32.63,0:09:36.13,Default,,0000,0000,0000,,And then when they push against\Nit, they take some of
Dialogue: 0,0:09:36.13,0:09:38.07,Default,,0000,0000,0000,,the membrane with them.
Dialogue: 0,0:09:38.07,0:09:41.26,Default,,0000,0000,0000,,Until eventually the cell\Nwill-- when this goes up
Dialogue: 0,0:09:41.26,0:09:43.81,Default,,0000,0000,0000,,enough, this'll pop together\Nand it'll take some of the
Dialogue: 0,0:09:43.81,0:09:44.56,Default,,0000,0000,0000,,membrane with it.
Dialogue: 0,0:09:44.56,0:09:47.28,Default,,0000,0000,0000,,And you could imagine why that\Nwould be useful thing
Dialogue: 0,0:09:47.28,0:09:49.03,Default,,0000,0000,0000,,to have with you.
Dialogue: 0,0:09:49.03,0:09:51.26,Default,,0000,0000,0000,,Because now that you have this\Nmembrane, you kind of look
Dialogue: 0,0:09:51.26,0:09:52.52,Default,,0000,0000,0000,,like this cell.
Dialogue: 0,0:09:52.52,0:09:55.30,Default,,0000,0000,0000,,So when you want to go infect\Nanother cell like this, you're
Dialogue: 0,0:09:55.30,0:09:58.53,Default,,0000,0000,0000,,not going to necessarily look\Nlike a foreign particle.
Dialogue: 0,0:09:58.53,0:10:02.78,Default,,0000,0000,0000,,So it's a very useful way to\Nlook like something that
Dialogue: 0,0:10:02.78,0:10:03.47,Default,,0000,0000,0000,,you're not.
Dialogue: 0,0:10:03.47,0:10:06.94,Default,,0000,0000,0000,,And if you don't think that this\Nis creepy-crawly enough,
Dialogue: 0,0:10:06.94,0:10:10.78,Default,,0000,0000,0000,,that you're hijacking the DNA\Nof an organism, viruses can
Dialogue: 0,0:10:10.78,0:10:14.74,Default,,0000,0000,0000,,actually change the\NDNA an organism.
Dialogue: 0,0:10:14.74,0:10:18.83,Default,,0000,0000,0000,,And actually one of the most\Ncommon examples is HIV virus.
Dialogue: 0,0:10:18.83,0:10:21.48,Default,,0000,0000,0000,,Let me write that down.
Dialogue: 0,0:10:21.48,0:10:27.48,Default,,0000,0000,0000,,HIV, which is a type of\Nretrovirus, which is
Dialogue: 0,0:10:27.48,0:10:28.28,Default,,0000,0000,0000,,fascinating.
Dialogue: 0,0:10:28.28,0:10:31.93,Default,,0000,0000,0000,,Because what they do is, so\Nthey have RNA in them.
Dialogue: 0,0:10:31.93,0:10:35.81,Default,,0000,0000,0000,,
Dialogue: 0,0:10:35.81,0:10:38.03,Default,,0000,0000,0000,,And when they enter into a cell,\Nlet's say that they got
Dialogue: 0,0:10:38.03,0:10:39.43,Default,,0000,0000,0000,,into the cell.
Dialogue: 0,0:10:39.43,0:10:42.95,Default,,0000,0000,0000,,So it's inside of the\Ncell like this.
Dialogue: 0,0:10:42.95,0:10:46.57,Default,,0000,0000,0000,,They actually bring along\Nwith them a protein.
Dialogue: 0,0:10:46.57,0:10:49.60,Default,,0000,0000,0000,,And every time you say, where\Ndo they get this protein?
Dialogue: 0,0:10:49.60,0:10:51.39,Default,,0000,0000,0000,,All of this stuff came from\Na different cell.
Dialogue: 0,0:10:51.39,0:10:54.49,Default,,0000,0000,0000,,They use some other cell's amino\Nacids and ribosomes and
Dialogue: 0,0:10:54.49,0:10:56.80,Default,,0000,0000,0000,,nucleic acids and everything\Nto build themselves.
Dialogue: 0,0:10:56.80,0:10:58.78,Default,,0000,0000,0000,,So any proteins that they\Nhave in them came
Dialogue: 0,0:10:58.78,0:11:00.08,Default,,0000,0000,0000,,from another cell.
Dialogue: 0,0:11:00.08,0:11:04.61,Default,,0000,0000,0000,,But they bring with them, this\Nprotein reverse transcriptase.
Dialogue: 0,0:11:04.61,0:11:07.85,Default,,0000,0000,0000,,And the reverse transcriptase\Ntakes their RNA and
Dialogue: 0,0:11:07.85,0:11:11.49,Default,,0000,0000,0000,,codes it into DNA.
Dialogue: 0,0:11:11.49,0:11:14.79,Default,,0000,0000,0000,,So its RNA to DNA.
Dialogue: 0,0:11:14.79,0:11:16.81,Default,,0000,0000,0000,,Which when it was first\Ndiscovered was, kind of,
Dialogue: 0,0:11:16.81,0:11:19.95,Default,,0000,0000,0000,,people always thought that you\Nalways went from DNA to RNA,
Dialogue: 0,0:11:19.95,0:11:22.11,Default,,0000,0000,0000,,but this kind of broke\Nthat paradigm.
Dialogue: 0,0:11:22.11,0:11:23.85,Default,,0000,0000,0000,,But it codes from RNA to DNA.
Dialogue: 0,0:11:23.85,0:11:29.02,Default,,0000,0000,0000,,And if that's not bad enough,\Nit'll incorporate that DNA
Dialogue: 0,0:11:29.02,0:11:31.35,Default,,0000,0000,0000,,into the DNA of the host cell.
Dialogue: 0,0:11:31.35,0:11:34.50,Default,,0000,0000,0000,,So that DNA will incorporate\Nitself into the
Dialogue: 0,0:11:34.50,0:11:35.20,Default,,0000,0000,0000,,DNA of the host cell.
Dialogue: 0,0:11:35.20,0:11:37.69,Default,,0000,0000,0000,,Let's say the yellow is the\NDNA of the host cell.
Dialogue: 0,0:11:37.69,0:11:41.00,Default,,0000,0000,0000,,And this is its nucleus.
Dialogue: 0,0:11:41.00,0:11:44.07,Default,,0000,0000,0000,,So it actually messes with\Nthe genetic makeup
Dialogue: 0,0:11:44.07,0:11:46.03,Default,,0000,0000,0000,,of what it's infecting.
Dialogue: 0,0:11:46.03,0:11:51.57,Default,,0000,0000,0000,,And when I made the videos on\Nbacteria I said, hey for every
Dialogue: 0,0:11:51.57,0:11:53.79,Default,,0000,0000,0000,,one human cell we have twenty\Nbacteria cells.
Dialogue: 0,0:11:53.79,0:11:56.42,Default,,0000,0000,0000,,And they live with us and\Nthey're useful and they're
Dialogue: 0,0:11:56.42,0:12:00.10,Default,,0000,0000,0000,,part of us and they're 10% of\Nour dry mass and all of that.
Dialogue: 0,0:12:00.10,0:12:02.17,Default,,0000,0000,0000,,But bacteria are kind of\Nalong for the ride.
Dialogue: 0,0:12:02.17,0:12:03.86,Default,,0000,0000,0000,,They don't change who we are.
Dialogue: 0,0:12:03.86,0:12:07.01,Default,,0000,0000,0000,,But these retroviruses, they're\Nactually changing our
Dialogue: 0,0:12:07.01,0:12:07.94,Default,,0000,0000,0000,,genetic makeup.
Dialogue: 0,0:12:07.94,0:12:10.65,Default,,0000,0000,0000,,I mean, my genes, I take\Nvery personally.
Dialogue: 0,0:12:10.65,0:12:12.38,Default,,0000,0000,0000,,They define who I am.
Dialogue: 0,0:12:12.38,0:12:14.63,Default,,0000,0000,0000,,But these guys will\Nactually go in and
Dialogue: 0,0:12:14.63,0:12:16.24,Default,,0000,0000,0000,,change my genetic makeup.
Dialogue: 0,0:12:16.24,0:12:19.30,Default,,0000,0000,0000,,And then once they're part of\Nthe DNA, then just the natural
Dialogue: 0,0:12:19.30,0:12:25.33,Default,,0000,0000,0000,,DNA to RNA to protein\Nprocess will code
Dialogue: 0,0:12:25.33,0:12:27.18,Default,,0000,0000,0000,,their actual proteins.
Dialogue: 0,0:12:27.18,0:12:30.16,Default,,0000,0000,0000,,Or their-- what they need to--\Nso sometimes they'll lay
Dialogue: 0,0:12:30.16,0:12:31.42,Default,,0000,0000,0000,,dormant and do nothing.
Dialogue: 0,0:12:31.42,0:12:33.73,Default,,0000,0000,0000,,And sometimes-- let's say\Nsometimes in some type of
Dialogue: 0,0:12:33.73,0:12:35.79,Default,,0000,0000,0000,,environmental trigger,\Nthey'll start coding
Dialogue: 0,0:12:35.79,0:12:37.11,Default,,0000,0000,0000,,for themselves again.
Dialogue: 0,0:12:37.11,0:12:38.62,Default,,0000,0000,0000,,And they'll start\Nproducing more.
Dialogue: 0,0:12:38.62,0:12:41.98,Default,,0000,0000,0000,,But they're producing it\Ndirectly from the organism's
Dialogue: 0,0:12:41.98,0:12:43.11,Default,,0000,0000,0000,,cell's DNA.
Dialogue: 0,0:12:43.11,0:12:45.12,Default,,0000,0000,0000,,They become part of\Nthe organism.
Dialogue: 0,0:12:45.12,0:12:49.28,Default,,0000,0000,0000,,I mean I can't imagine a more\Nintimate way to become part of
Dialogue: 0,0:12:49.28,0:12:51.53,Default,,0000,0000,0000,,an organism than to become\Npart of its DNA.
Dialogue: 0,0:12:51.53,0:12:52.87,Default,,0000,0000,0000,,I can't imagine any\Nother way to
Dialogue: 0,0:12:52.87,0:12:55.68,Default,,0000,0000,0000,,actually define an organism.
Dialogue: 0,0:12:55.68,0:13:00.91,Default,,0000,0000,0000,,And if this by itself is not\Neerie enough, and just so you
Dialogue: 0,0:13:00.91,0:13:06.77,Default,,0000,0000,0000,,know, this notion right here,\Nwhen a virus becomes part of
Dialogue: 0,0:13:06.77,0:13:09.43,Default,,0000,0000,0000,,an organism's DNA, this\Nis called a provirus.
Dialogue: 0,0:13:09.43,0:13:13.18,Default,,0000,0000,0000,,
Dialogue: 0,0:13:13.18,0:13:16.89,Default,,0000,0000,0000,,But if this isn't eerie enough,\Nthey estimate-- so if
Dialogue: 0,0:13:16.89,0:13:23.50,Default,,0000,0000,0000,,this infects a cell in my nose\Nor in my arm, as this cell
Dialogue: 0,0:13:23.50,0:13:27.25,Default,,0000,0000,0000,,experiences mitosis, all of\Nits offspring-- but its
Dialogue: 0,0:13:27.25,0:13:29.03,Default,,0000,0000,0000,,offspring are genetically\Nidentical-- are going to have
Dialogue: 0,0:13:29.03,0:13:30.60,Default,,0000,0000,0000,,this viral DNA.
Dialogue: 0,0:13:30.60,0:13:32.06,Default,,0000,0000,0000,,And that might be fine,\Nbut at least my
Dialogue: 0,0:13:32.06,0:13:33.12,Default,,0000,0000,0000,,children won't get it.
Dialogue: 0,0:13:33.12,0:13:35.98,Default,,0000,0000,0000,,You know, at least it won't\Nbecome part of my species.
Dialogue: 0,0:13:35.98,0:13:38.71,Default,,0000,0000,0000,,But it doesn't have to just\Ninfect somatic cells, it could
Dialogue: 0,0:13:38.71,0:13:41.17,Default,,0000,0000,0000,,infect a germ cell.
Dialogue: 0,0:13:41.17,0:13:44.51,Default,,0000,0000,0000,,So it could go into\Na germ cell.
Dialogue: 0,0:13:44.51,0:13:46.85,Default,,0000,0000,0000,,And the germ cells, we've\Nlearned already, these are the
Dialogue: 0,0:13:46.85,0:13:49.38,Default,,0000,0000,0000,,ones that produce gametes.
Dialogue: 0,0:13:49.38,0:13:52.93,Default,,0000,0000,0000,,For men, that's sperm and\Nfor women it's eggs.
Dialogue: 0,0:13:52.93,0:13:55.18,Default,,0000,0000,0000,,But you could imagine, once\Nyou've infected a germ cell,
Dialogue: 0,0:13:55.18,0:13:59.01,Default,,0000,0000,0000,,once you become part of a germ\Ncell's DNA, then I'm passing
Dialogue: 0,0:13:59.01,0:14:02.60,Default,,0000,0000,0000,,on that viral DNA to my\Nson or my daughter.
Dialogue: 0,0:14:02.60,0:14:05.54,Default,,0000,0000,0000,,And they are going to pass\Nit on to their children.
Dialogue: 0,0:14:05.54,0:14:10.26,Default,,0000,0000,0000,,And just that idea by itself\Nis, at least to my mind.
Dialogue: 0,0:14:10.26,0:14:12.13,Default,,0000,0000,0000,,vaguely creepy.
Dialogue: 0,0:14:12.13,0:14:16.05,Default,,0000,0000,0000,,And people estimate that 5-8%--\Nand this kind of really
Dialogue: 0,0:14:16.05,0:14:19.48,Default,,0000,0000,0000,,blurs, it makes you think about\Nwhat we as humans really
Dialogue: 0,0:14:19.48,0:14:26.80,Default,,0000,0000,0000,,are-- but the estimate is 5-8%\Nof the human genome-- so when
Dialogue: 0,0:14:26.80,0:14:29.50,Default,,0000,0000,0000,,I talked about bacteria I just\Ntalked about things that were
Dialogue: 0,0:14:29.50,0:14:30.85,Default,,0000,0000,0000,,along for the ride.
Dialogue: 0,0:14:30.85,0:14:33.24,Default,,0000,0000,0000,,But the current estimate, and\NI looked up this a lot.
Dialogue: 0,0:14:33.24,0:14:35.21,Default,,0000,0000,0000,,I found 8% someplace,\N5% someplace.
Dialogue: 0,0:14:35.21,0:14:35.99,Default,,0000,0000,0000,,It's all a guess.
Dialogue: 0,0:14:35.99,0:14:37.65,Default,,0000,0000,0000,,I mean people are doing it based\Non just looking at the
Dialogue: 0,0:14:37.65,0:14:40.69,Default,,0000,0000,0000,,DNA and how similar it is to\NDNA in other organisms. But
Dialogue: 0,0:14:40.69,0:14:47.39,Default,,0000,0000,0000,,the estimate is 5-8% of the\Nhuman genome is from viruses,
Dialogue: 0,0:14:47.39,0:14:51.76,Default,,0000,0000,0000,,is from ancient retroviruses\Nthat incorporated themselves
Dialogue: 0,0:14:51.76,0:14:53.53,Default,,0000,0000,0000,,into the human germ line.
Dialogue: 0,0:14:53.53,0:14:55.72,Default,,0000,0000,0000,,So into the human DNA.
Dialogue: 0,0:14:55.72,0:14:57.86,Default,,0000,0000,0000,,So these are called endogenous\Nretroviruses.
Dialogue: 0,0:14:57.86,0:15:04.80,Default,,0000,0000,0000,,
Dialogue: 0,0:15:04.80,0:15:07.15,Default,,0000,0000,0000,,Which is mind blowing to me,\Nbecause it's not just saying
Dialogue: 0,0:15:07.15,0:15:09.29,Default,,0000,0000,0000,,these things are along for the\Nride or that they might help
Dialogue: 0,0:15:09.29,0:15:10.07,Default,,0000,0000,0000,,us or hurt us.
Dialogue: 0,0:15:10.07,0:15:14.00,Default,,0000,0000,0000,,It's saying that we are--\N5-8% of our DNA
Dialogue: 0,0:15:14.00,0:15:16.39,Default,,0000,0000,0000,,actually comes from viruses.
Dialogue: 0,0:15:16.39,0:15:17.85,Default,,0000,0000,0000,,And this is another thing\Nthat speaks to
Dialogue: 0,0:15:17.85,0:15:19.72,Default,,0000,0000,0000,,just genetic variation.
Dialogue: 0,0:15:19.72,0:15:24.21,Default,,0000,0000,0000,,Because viruses do something--\NI mean this is called
Dialogue: 0,0:15:24.21,0:15:27.76,Default,,0000,0000,0000,,horizontal transfer of DNA.
Dialogue: 0,0:15:27.76,0:15:30.48,Default,,0000,0000,0000,,And you could imagine, as a\Nvirus goes from one species to
Dialogue: 0,0:15:30.48,0:15:37.22,Default,,0000,0000,0000,,the next, as it goes from\NSpecies A to B, if it mutates
Dialogue: 0,0:15:37.22,0:15:41.31,Default,,0000,0000,0000,,to be able to infiltrate these\Ncells, it might take some--
Dialogue: 0,0:15:41.31,0:15:43.81,Default,,0000,0000,0000,,it'll take the DNA that\Nit already has, that
Dialogue: 0,0:15:43.81,0:15:45.49,Default,,0000,0000,0000,,makes it, it with it.
Dialogue: 0,0:15:45.49,0:15:48.18,Default,,0000,0000,0000,,But sometimes, when it starts\Ncoding for some of these other
Dialogue: 0,0:15:48.18,0:15:52.83,Default,,0000,0000,0000,,guys, so let's say that this\Nis a provirus right here.
Dialogue: 0,0:15:52.83,0:15:55.86,Default,,0000,0000,0000,,Where the blue part is\Nthe original virus.
Dialogue: 0,0:15:55.86,0:16:00.96,Default,,0000,0000,0000,,The yellow is the organism's\Nhistoric DNA.
Dialogue: 0,0:16:00.96,0:16:04.23,Default,,0000,0000,0000,,Sometimes when it codes, it\Ntakes up little sections of
Dialogue: 0,0:16:04.23,0:16:07.20,Default,,0000,0000,0000,,the other organism's DNA.
Dialogue: 0,0:16:07.20,0:16:11.81,Default,,0000,0000,0000,,So maybe most of it was the\Nviral DNA, but it might have,
Dialogue: 0,0:16:11.81,0:16:14.07,Default,,0000,0000,0000,,when it transcribed and\Ntranslated itself, it might
Dialogue: 0,0:16:14.07,0:16:16.71,Default,,0000,0000,0000,,have taken a little bit-- or at\Nleast when it translated or
Dialogue: 0,0:16:16.71,0:16:18.46,Default,,0000,0000,0000,,replicated itself-- it might\Ntake a little bit of the
Dialogue: 0,0:16:18.46,0:16:20.54,Default,,0000,0000,0000,,organism's previous DNA.
Dialogue: 0,0:16:20.54,0:16:23.69,Default,,0000,0000,0000,,So it's actually cutting parts\Nof DNA from one organism and
Dialogue: 0,0:16:23.69,0:16:24.95,Default,,0000,0000,0000,,bringing it to another\Norganism.
Dialogue: 0,0:16:24.95,0:16:27.49,Default,,0000,0000,0000,,Taking it from one member of a\Nspecies to another member of
Dialogue: 0,0:16:27.49,0:16:27.81,Default,,0000,0000,0000,,the species.
Dialogue: 0,0:16:27.81,0:16:29.75,Default,,0000,0000,0000,,But it can definitely\Ngo cross-species.
Dialogue: 0,0:16:29.75,0:16:32.86,Default,,0000,0000,0000,,So you have this idea all of\Na sudden that DNA can jump
Dialogue: 0,0:16:32.86,0:16:34.09,Default,,0000,0000,0000,,between species.
Dialogue: 0,0:16:34.09,0:16:36.41,Default,,0000,0000,0000,,It really kind of-- I don't\Nknow, for me it makes me
Dialogue: 0,0:16:36.41,0:16:39.93,Default,,0000,0000,0000,,appreciate how interconnected--\Nas a species,
Dialogue: 0,0:16:39.93,0:16:41.95,Default,,0000,0000,0000,,we kind of imagine that we're\Nby ourselves and can only
Dialogue: 0,0:16:41.95,0:16:45.11,Default,,0000,0000,0000,,reproduce with each other and\Nhave genetic variation within
Dialogue: 0,0:16:45.11,0:16:45.86,Default,,0000,0000,0000,,a population.
Dialogue: 0,0:16:45.86,0:16:50.19,Default,,0000,0000,0000,,But viruses introduce this\Nnotion of horizontal transfer
Dialogue: 0,0:16:50.19,0:16:53.09,Default,,0000,0000,0000,,via transduction.
Dialogue: 0,0:16:53.09,0:16:57.64,Default,,0000,0000,0000,,Horizontal transduction is just\Nthe idea of, look when I
Dialogue: 0,0:16:57.64,0:17:00.66,Default,,0000,0000,0000,,replicate this virus, I might\Ntake a little bit of the
Dialogue: 0,0:17:00.66,0:17:04.35,Default,,0000,0000,0000,,organism that I'm freeloading\Noff of, I might take a little
Dialogue: 0,0:17:04.35,0:17:06.01,Default,,0000,0000,0000,,bit of their DNA with me.
Dialogue: 0,0:17:06.01,0:17:09.16,Default,,0000,0000,0000,,And infect that DNA into\Nthe next organism.
Dialogue: 0,0:17:09.16,0:17:11.33,Default,,0000,0000,0000,,So you actually have this\NDNA, this jumping,
Dialogue: 0,0:17:11.33,0:17:13.12,Default,,0000,0000,0000,,from organism to organism.
Dialogue: 0,0:17:13.12,0:17:17.30,Default,,0000,0000,0000,,So it kind of unifies\Nall DNA-based life.
Dialogue: 0,0:17:17.30,0:17:20.61,Default,,0000,0000,0000,,Which is all the life that\Nwe know on the planet.
Dialogue: 0,0:17:20.61,0:17:24.90,Default,,0000,0000,0000,,And if all of this isn't creepy\Nenough-- and actually
Dialogue: 0,0:17:24.90,0:17:28.54,Default,,0000,0000,0000,,maybe I'll save the creepiest\Npart for the end.
Dialogue: 0,0:17:28.54,0:17:30.80,Default,,0000,0000,0000,,But there's a whole-- we could\Ntalk all about the different
Dialogue: 0,0:17:30.80,0:17:31.67,Default,,0000,0000,0000,,classes of viruses.
Dialogue: 0,0:17:31.67,0:17:33.81,Default,,0000,0000,0000,,But just so you're familiar with\Nsome of the terminology,
Dialogue: 0,0:17:33.81,0:17:37.90,Default,,0000,0000,0000,,when a virus attacks bacteria,\Nwhich they often do.
Dialogue: 0,0:17:37.90,0:17:41.15,Default,,0000,0000,0000,,And we study these the most\Nbecause this might be a good
Dialogue: 0,0:17:41.15,0:17:42.63,Default,,0000,0000,0000,,alternative to antibiotics.
Dialogue: 0,0:17:42.63,0:17:45.43,Default,,0000,0000,0000,,Because viruses that attack\Nbacteria might-- sometimes the
Dialogue: 0,0:17:45.43,0:17:47.82,Default,,0000,0000,0000,,bacteria is far worse for the\Nvirus-- but these are called
Dialogue: 0,0:17:47.82,0:17:49.07,Default,,0000,0000,0000,,bacteriaphages.
Dialogue: 0,0:17:49.07,0:17:52.61,Default,,0000,0000,0000,,
Dialogue: 0,0:17:52.61,0:17:55.32,Default,,0000,0000,0000,,And I've already talked to you\Nabout how they have their DNA.
Dialogue: 0,0:17:55.32,0:17:57.89,Default,,0000,0000,0000,,But since bacteria have hard\Nwalls, they will just inject
Dialogue: 0,0:17:57.89,0:18:00.94,Default,,0000,0000,0000,,the DNA inside of\Nthe bacteria.
Dialogue: 0,0:18:00.94,0:18:06.63,Default,,0000,0000,0000,,And when you talk about DNA,\Nthis idea of a provirus.
Dialogue: 0,0:18:06.63,0:18:09.17,Default,,0000,0000,0000,,So when a virus lyses it\Nlike this, this is
Dialogue: 0,0:18:09.17,0:18:11.09,Default,,0000,0000,0000,,called the lytic cycle.
Dialogue: 0,0:18:11.09,0:18:13.76,Default,,0000,0000,0000,,This is just some terminology\Nthat's good to know if you're
Dialogue: 0,0:18:13.76,0:18:16.25,Default,,0000,0000,0000,,going to take a biology\Nexam about this stuff.
Dialogue: 0,0:18:16.25,0:18:18.60,Default,,0000,0000,0000,,And when the virus incorporates\Nit into the DNA
Dialogue: 0,0:18:18.60,0:18:22.35,Default,,0000,0000,0000,,and lays dormant, incorporates\Ninto the DNA of the host
Dialogue: 0,0:18:22.35,0:18:25.42,Default,,0000,0000,0000,,organism and lays dormant for\Nawhile, this is called the
Dialogue: 0,0:18:25.42,0:18:28.03,Default,,0000,0000,0000,,lysogenic cycle.
Dialogue: 0,0:18:28.03,0:18:32.03,Default,,0000,0000,0000,,And normally, a provirus is\Nessentially experiencing a
Dialogue: 0,0:18:32.03,0:18:35.91,Default,,0000,0000,0000,,lysogenic cycle in eurkaryotes,\Nin organisms that
Dialogue: 0,0:18:35.91,0:18:38.25,Default,,0000,0000,0000,,have a nuclear membrane.
Dialogue: 0,0:18:38.25,0:18:40.89,Default,,0000,0000,0000,,Normally when people talk about\Nthe lysogenic cycle,
Dialogue: 0,0:18:40.89,0:18:44.75,Default,,0000,0000,0000,,they're talking about viral DNA\Nlaying dormant in the DNA
Dialogue: 0,0:18:44.75,0:18:45.60,Default,,0000,0000,0000,,of bacteria.
Dialogue: 0,0:18:45.60,0:18:48.60,Default,,0000,0000,0000,,Or bacteriophage DNA\Nlaying dormant
Dialogue: 0,0:18:48.60,0:18:51.05,Default,,0000,0000,0000,,in the DNA of bacteria.
Dialogue: 0,0:18:51.05,0:18:53.38,Default,,0000,0000,0000,,But just to kind of give you\Nan idea of what this, quote
Dialogue: 0,0:18:53.38,0:18:59.48,Default,,0000,0000,0000,,unquote, looks like,\Nright here.
Dialogue: 0,0:18:59.48,0:19:01.55,Default,,0000,0000,0000,,I got these two pictures\Nfrom Wikipedia.
Dialogue: 0,0:19:01.55,0:19:02.80,Default,,0000,0000,0000,,One is from the CDC.
Dialogue: 0,0:19:02.80,0:19:11.36,Default,,0000,0000,0000,,
Dialogue: 0,0:19:11.36,0:19:14.20,Default,,0000,0000,0000,,These little green dots you see\Nright here all over the
Dialogue: 0,0:19:14.20,0:19:17.54,Default,,0000,0000,0000,,surface, this big thing you\Nsee here, this is a white
Dialogue: 0,0:19:17.54,0:19:20.33,Default,,0000,0000,0000,,blood cell.
Dialogue: 0,0:19:20.33,0:19:21.76,Default,,0000,0000,0000,,Part of the human\Nimmune system.
Dialogue: 0,0:19:21.76,0:19:23.05,Default,,0000,0000,0000,,This is a white blood cell.
Dialogue: 0,0:19:23.05,0:19:27.54,Default,,0000,0000,0000,,
Dialogue: 0,0:19:27.54,0:19:31.06,Default,,0000,0000,0000,,And what you see emerging from\Nthe surface, essentially
Dialogue: 0,0:19:31.06,0:19:34.51,Default,,0000,0000,0000,,budding from the surface of this\Nwhite blood cell-- and
Dialogue: 0,0:19:34.51,0:19:36.30,Default,,0000,0000,0000,,this gives you a sense\Nof scale too--
Dialogue: 0,0:19:36.30,0:19:39.70,Default,,0000,0000,0000,,these are HIV-1 viruses.
Dialogue: 0,0:19:39.70,0:19:46.97,Default,,0000,0000,0000,,And so you're familiar with the\Nterminology, the HIV is a
Dialogue: 0,0:19:46.97,0:19:51.81,Default,,0000,0000,0000,,virus that infects white\Nblood cells.
Dialogue: 0,0:19:51.81,0:19:54.89,Default,,0000,0000,0000,,AIDS is the syndrome you get\Nonce your immune system is
Dialogue: 0,0:19:54.89,0:19:55.90,Default,,0000,0000,0000,,weakened to the point.
Dialogue: 0,0:19:55.90,0:19:58.86,Default,,0000,0000,0000,,And then many people suffer\Ninfections that people with a
Dialogue: 0,0:19:58.86,0:20:01.45,Default,,0000,0000,0000,,strong immune system normally\Nwon't suffer from.
Dialogue: 0,0:20:01.45,0:20:03.05,Default,,0000,0000,0000,,But this is creepy.
Dialogue: 0,0:20:03.05,0:20:06.36,Default,,0000,0000,0000,,These things went inside this\Nhuge cell, they used the
Dialogue: 0,0:20:06.36,0:20:11.56,Default,,0000,0000,0000,,cell's own mechanism to\Nreproduce its own DNA or its
Dialogue: 0,0:20:11.56,0:20:14.30,Default,,0000,0000,0000,,own RNA and these\Nprotein capsids.
Dialogue: 0,0:20:14.30,0:20:16.27,Default,,0000,0000,0000,,And then they bud from the cell\Nand take a little bit of
Dialogue: 0,0:20:16.27,0:20:17.49,Default,,0000,0000,0000,,the membrane with it.
Dialogue: 0,0:20:17.49,0:20:20.99,Default,,0000,0000,0000,,And they can even leave some\Nof their DNA behind in this
Dialogue: 0,0:20:20.99,0:20:22.34,Default,,0000,0000,0000,,cell's own DNA.
Dialogue: 0,0:20:22.34,0:20:25.28,Default,,0000,0000,0000,,So they really change what\Nthe cell is all about.
Dialogue: 0,0:20:25.28,0:20:26.89,Default,,0000,0000,0000,,This is another creepy\Npicture.
Dialogue: 0,0:20:26.89,0:20:28.14,Default,,0000,0000,0000,,These are bacteriaphages.
Dialogue: 0,0:20:28.14,0:20:34.50,Default,,0000,0000,0000,,
Dialogue: 0,0:20:34.50,0:20:36.11,Default,,0000,0000,0000,,And these show you what\NI said before.
Dialogue: 0,0:20:36.11,0:20:38.45,Default,,0000,0000,0000,,This is a bacteria right here.
Dialogue: 0,0:20:38.45,0:20:41.36,Default,,0000,0000,0000,,This is its cell wall.
Dialogue: 0,0:20:41.36,0:20:42.10,Default,,0000,0000,0000,,And it's hard.
Dialogue: 0,0:20:42.10,0:20:45.02,Default,,0000,0000,0000,,So it's hard to just\Nemerge into it.
Dialogue: 0,0:20:45.02,0:20:47.04,Default,,0000,0000,0000,,Or you can't just merge,\Nfuse membranes with it.
Dialogue: 0,0:20:47.04,0:20:52.29,Default,,0000,0000,0000,,So they hang out on the outside\Nof this bacteria.
Dialogue: 0,0:20:52.29,0:20:55.41,Default,,0000,0000,0000,,And they are essentially\Ninjecting their genetic
Dialogue: 0,0:20:55.41,0:20:58.28,Default,,0000,0000,0000,,material into the\Nbacteria itself.
Dialogue: 0,0:20:58.28,0:20:59.89,Default,,0000,0000,0000,,And you could imagine,\Njust looking at the
Dialogue: 0,0:20:59.89,0:21:01.00,Default,,0000,0000,0000,,size of these things.
Dialogue: 0,0:21:01.00,0:21:02.09,Default,,0000,0000,0000,,I mean, this is a cell.
Dialogue: 0,0:21:02.09,0:21:04.35,Default,,0000,0000,0000,,And it looks like a whole\Nplanet or something.
Dialogue: 0,0:21:04.35,0:21:05.65,Default,,0000,0000,0000,,Or this is a bacteria and these
Dialogue: 0,0:21:05.65,0:21:06.62,Default,,0000,0000,0000,,things are so much smaller.
Dialogue: 0,0:21:06.62,0:21:08.17,Default,,0000,0000,0000,,Roughly 1/100 of a bacteria.
Dialogue: 0,0:21:08.17,0:21:10.57,Default,,0000,0000,0000,,And these are much less than\N1/100 of this cell we're
Dialogue: 0,0:21:10.57,0:21:11.11,Default,,0000,0000,0000,,talking about.
Dialogue: 0,0:21:11.11,0:21:15.51,Default,,0000,0000,0000,,And they're extremely\Nhard to filter for.
Dialogue: 0,0:21:15.51,0:21:16.52,Default,,0000,0000,0000,,To kind of keep out.
Dialogue: 0,0:21:16.52,0:21:20.78,Default,,0000,0000,0000,,Because they are such,\Nsuch small particles.
Dialogue: 0,0:21:20.78,0:21:23.29,Default,,0000,0000,0000,,If you think that these are\Nexotic things that exist for
Dialogue: 0,0:21:23.29,0:21:31.36,Default,,0000,0000,0000,,things like HIV or Ebola , which\Nthey do cause, or SARS,
Dialogue: 0,0:21:31.36,0:21:32.34,Default,,0000,0000,0000,,you're right.
Dialogue: 0,0:21:32.34,0:21:33.73,Default,,0000,0000,0000,,But they're also\Ncommon things.
Dialogue: 0,0:21:33.73,0:21:35.49,Default,,0000,0000,0000,,I mean, I said at the beginning\Nof this video that I
Dialogue: 0,0:21:35.49,0:21:36.30,Default,,0000,0000,0000,,have a cold.
Dialogue: 0,0:21:36.30,0:21:40.04,Default,,0000,0000,0000,,And I have a cold because some\Nviruses have infected the
Dialogue: 0,0:21:40.04,0:21:42.61,Default,,0000,0000,0000,,tissue in my nasal passage.
Dialogue: 0,0:21:42.61,0:21:46.19,Default,,0000,0000,0000,,And they're causing me to have\Na runny nose and whatnot.
Dialogue: 0,0:21:46.19,0:21:48.54,Default,,0000,0000,0000,,And viruses also cause\Nthe chicken pox.
Dialogue: 0,0:21:48.54,0:21:50.55,Default,,0000,0000,0000,,They cause the herpes\Nsimplex virus.
Dialogue: 0,0:21:50.55,0:21:51.54,Default,,0000,0000,0000,,Causes cold sores.
Dialogue: 0,0:21:51.54,0:21:53.43,Default,,0000,0000,0000,,So they're with us all around.
Dialogue: 0,0:21:53.43,0:21:56.00,Default,,0000,0000,0000,,I can almost guarantee\Nyou have some virus
Dialogue: 0,0:21:56.00,0:21:57.74,Default,,0000,0000,0000,,with you as you speak.
Dialogue: 0,0:21:57.74,0:21:58.63,Default,,0000,0000,0000,,They're all around you.
Dialogue: 0,0:21:58.63,0:22:04.32,Default,,0000,0000,0000,,But it's a very
Dialogue: 0,0:22:04.32,0:22:06.48,Default,,0000,0000,0000,,philosophically puzzling question.
Dialogue: 0,0:22:06.48,0:22:09.09,Default,,0000,0000,0000,,Because I started with, at the\Nbeginning, are these life?
Dialogue: 0,0:22:09.09,0:22:11.50,Default,,0000,0000,0000,,And at first when I just showed\Nit to you, look they
Dialogue: 0,0:22:11.50,0:22:13.74,Default,,0000,0000,0000,,are just this protein\Nwith some nucleic
Dialogue: 0,0:22:13.74,0:22:15.28,Default,,0000,0000,0000,,acid molecule in it.
Dialogue: 0,0:22:15.28,0:22:16.34,Default,,0000,0000,0000,,And it's not doing anything.
Dialogue: 0,0:22:16.34,0:22:17.78,Default,,0000,0000,0000,,And that doesn't look\Nlike life to me.
Dialogue: 0,0:22:17.78,0:22:18.61,Default,,0000,0000,0000,,It's not moving around.
Dialogue: 0,0:22:18.61,0:22:19.66,Default,,0000,0000,0000,,It doesn't have a metabolism.
Dialogue: 0,0:22:19.66,0:22:20.39,Default,,0000,0000,0000,,It's not eating.
Dialogue: 0,0:22:20.39,0:22:21.56,Default,,0000,0000,0000,,It's not reproducing.
Dialogue: 0,0:22:21.56,0:22:23.12,Default,,0000,0000,0000,,But then all of a sudden, when\Nyou think about what it's
Dialogue: 0,0:22:23.12,0:22:27.13,Default,,0000,0000,0000,,doing to cells and how it uses\Ncells to kind of reproduce.
Dialogue: 0,0:22:27.13,0:22:29.70,Default,,0000,0000,0000,,It kind of like-- in business\Nterms it's asset light.
Dialogue: 0,0:22:29.70,0:22:31.92,Default,,0000,0000,0000,,It doesn't need all of the\Nmachinery because it can use
Dialogue: 0,0:22:31.92,0:22:35.85,Default,,0000,0000,0000,,other people's machinery\Nto replicate itself.
Dialogue: 0,0:22:35.85,0:22:38.08,Default,,0000,0000,0000,,You almost kind of want\Nto view it as a
Dialogue: 0,0:22:38.08,0:22:39.52,Default,,0000,0000,0000,,smarter form of life.
Dialogue: 0,0:22:39.52,0:22:42.48,Default,,0000,0000,0000,,Because it doesn't go through\Nall of the trouble of what
Dialogue: 0,0:22:42.48,0:22:44.11,Default,,0000,0000,0000,,every other form of life has.
Dialogue: 0,0:22:44.11,0:22:47.57,Default,,0000,0000,0000,,It makes you question what life\Nis, or even what we are.
Dialogue: 0,0:22:47.57,0:22:51.51,Default,,0000,0000,0000,,Are we these things that contain\NDNA or are we just
Dialogue: 0,0:22:51.51,0:22:54.17,Default,,0000,0000,0000,,transport mechanisms\Nfor the DNA?
Dialogue: 0,0:22:54.17,0:22:56.26,Default,,0000,0000,0000,,And these are kind of the\Nmore important things.
Dialogue: 0,0:22:56.26,0:22:59.71,Default,,0000,0000,0000,,And these viral infections are\Njust battles between different
Dialogue: 0,0:22:59.71,0:23:02.34,Default,,0000,0000,0000,,forms of DNA and RNA\Nand whatnot.
Dialogue: 0,0:23:02.34,0:23:04.33,Default,,0000,0000,0000,,Anyway I don't want to get\Ntoo philosophical on you.
Dialogue: 0,0:23:04.33,0:23:08.84,Default,,0000,0000,0000,,But hopefully this gives you a\Ngood idea of what viruses are
Dialogue: 0,0:23:08.84,0:23:12.94,Default,,0000,0000,0000,,and why they really are, in my\Nmind, the most fascinating
Dialogue: 0,0:23:12.94,0:23:15.87,Default,,0000,0000,0000,,pseudo organism in\Nall of biology.
Dialogue: 0,0:23:15.87,0:23:16.28,Default,,0000,0000,0000,,