Viruses (Updated)


Subtitles on! Click CC at bottom right to turn off. You can find us on Twitter (@AmoebaSisters) and Facebook! Chances are, in your life, you’ve had the
common cold before. It can cause sneezing and coughing and just
makes you feel awful. The worst thing about the common cold is that
you can take medications to help with the symptoms, but you really can’t treat the
actual cold with antibiotics like you would a strep throat infection or an infected tooth. Why? Well let’s talk about what causes it: a
virus. The common cold is caused by a virus. And while all living things are made of 1
or more cells—see the modern cell theory—viruses are not cells. Viruses aren’t technically classified as
living things since they lack many characteristics of life, but there is debate in calling them
nonliving as well. Medications like antibiotics attack bacteria
like E.coli which are living cells. Anti-fungal medications can be used on fungi
like athlete’s foot which are made of living cells. Viruses are not bacteria or fungi. You can’t classify a virus as a prokaryote
or a eukaryote either because it’s not a cell. So what is their structure like? First of all, viruses are much, much smaller
than cells. You typically are going to need an electron
microscope in order to see a virus. Viruses come in many shapes. Our favorite one to draw is the bacteriophage! It sounds very fancy, but it is a type of
virus that tends to attack bacteria. Despite this being our favorite to draw, know
that the shape of viruses vary. Greatly. One thing all viruses have in common is that
they have some type of genetic material. This genetic material can be in the form of
DNA or RNA. Viruses usually have some kind protein coat,
also known as a capsid. The capsid can protect that DNA or RNA genetic
material. Viruses can also can have other structures. Some viruses package special enzymes with
them. Some viruses have an outer envelope. These additions can be useful to the virus
in virus replication. One thing that makes virus replication, or
reproduction, unique is that they can’t replicate without a host. And it’s their reproducing that tends to
be a problem for its host: whether the host is you — in the case of a common cold—,
an insect, plant, or this bacterium. Viruses tend to be very specific for the host
that they’re going to go infect, but anything that is alive can be a host, because cells
have the machinery viruses need in order to replicate. We’re going to talk about two types of viral
replication cycles. The first one is the lytic cycle. In the lytic cycle, the virus, remember very
selective, attaches to a host cell. It often binds to a receptor that this cell
has which gives it access to dock there. The virus can then inject either its DNA or
RNA, depending on what kind of genetic material it has, into the cell. Some types of viruses are actually taken inside
the cell themselves. Now you would think the cell would notice
viral DNA or RNA or an entire virus that has been taken in, but in many cases it does not. It takes the genetic material from the virus
and it starts following the instructions, which in this case is very bad, because the
instructions tell it to makes copies of the virus. The cell uses its own resources to start building. It starts making so many copies of the virus
that it can cause the cell membrane of the host to rupture, explode, lyse! So what happens is now these new viral copies
get out of the cell, and they go and infect other cells. This is known as the lytic cycle. By the way, the lysing of the cell membrane
is a very bad thing for the cell. The cell cannot survive without its cell membrane. The other cycle is called the lysogenic cycle,
and I like to remember this is the longer word so I like to think of this as the longer,
sneaky cycle. Viruses that go through this cycle tend to
do the same thing at the beginning. They inject their genetic material, but this
time, the genetic material stays hidden in the host’s genetic material. What happens is that when the host makes new
cells, it replicates its own genetic material and the viral genetic material. Then those daughter cells make new cells,
and they also replicate their own genetic material and the viral genetic material. And so on. That is the lysogenic cycle. That may not seem like a problem, but it really
becomes one if it gets triggered to go into the lytic cycle from that point, because then
all of those cells that had the viral genetic material can start assembling viruses. As far as what triggers it to go into the
lytic cycle, it can vary. It could be a chemical trigger for example
or a lack of food for the host. Going back to the common cold, a lot of times
it has to run its course. Your immune system will typically take care
of it and medications can help the symptoms feel not as bad. But, unfortunately, some viruses are extremely
complicated, such as HIV, a virus that can lead to AIDS. Like most viruses, it is very specific. It binds to a CD4 glycoprotein that is found
on the surface of specific cells such as Helper T cells. The problem about this particular target is
that Helper T cells play an important role in protecting the body in the immune system. Since HIV goes after these immune cells, it
can make a person that is infected with HIV vulnerable to other infections. There are medications that have been developed
to help keep HIV from replicating as quickly, and there continues to be research looking
into ways to keep the virus from attaching—because if the virus can’t attach—it can’t insert
its genetic material. A problem that continues to be a challenge
is that many viruses, including HIV, can mutate. So a treatment developed against a certain
virus type may not work on a mutated form. So with our talk about viruses, you might
wonder, “Is there anything positive about viruses?” Well, viruses can play a useful role in gene
therapy. Definitely something to explore more. Also, remember how we mentioned that viruses
can go after other organisms like insects for example? Some of these viruses can target certain types
of pest insects. A virus that targets pest insects could be
an alternative to a chemical pesticide. One such example virus that you may want to
explore is the Nuclear Polyhedrosis Virus. Still, it’s important to consider that whenever
talking about any kind of pesticide—chemical or viral—there could be consequences
in the ecosystem. Well, that’s it for the Amoeba Sisters and
we remind you to stay curious!

100 thoughts on “Viruses (Updated)”

  1. This topic is now an Unlectured Series topic! https://www.amoebasisters.com/unlectured One of the question starters in the Unlectured topic mentions two therapies still being explored that can use viruses: phage therapy and gene therapy. Something fascinating to research if you have an interest in learning more about viruses.

  2. My only caveat with this video is about the lysis stage. The viruses don't simply fill up the cell and cause it to burst, they actually have proteins like neuraminidase that cleave parts of the inner membrane to cause lysis. But otherwise, great video!

  3. Ahhh ik this is not the best way of studying for the exam but i’d really rather watch this than study the book we barely even used lol

  4. Viruses are legit the demons of the universe like god wouldnt make this so obiously satan did.. I mean i have a virus at the point of this comment… IM LITERALLY PRAYING FOR IT TO STOP

  5. get you ozone dimmadome chromosome no hoe smoe joe knows no naruto down low infinity stone yo bro zone jemmadieah tho t pose skeet snow big tow small toe wevideo crap out of my sight.

  6. This video is really useful and easy to understand, but we were taught:
    Viruses don't have DNA, that's a very common mistake. They have Viral Genetic Material which is similar, but not the same thing as DNA. They cannot have DNA because they aren't living cells.

    You mentioned that they inject their DNA or RNA so I just wanted to make sure which theory is correct, I don't want to miss any marks in my GCSEs on this topic. Hopefully you'll reply to this comment ♥

  7. I usually don’t comment but this time I had to!!! You guys are hilarious!!! And of course helpful !! I love your videos ! So fun and entertaining to watch ❤️❤️❤️❤️” did I leave the oven on “ 😂😂😂

  8. Hello everyone, I have a question about PCR detection of a virus of other mikroorganism. I have been searching for the answer i both my books and on the web but not been able to find at clear answer. It's probably fairly easy to answer, i just what to be completely sure so i wont get a question wrong for the exam this summer. I know how the PCR tecnique works and obviously you should use reverse-transcriptase PCR (RT-PCR) for all the RNA virusses. My question goes:

    You want to detect a virus and found out which virus infection a patient have. You take a sample from where you assume the virus will be, maybe feces or saliva. Then you run your PCR or RT-PCR, but don't you have to run multiple PCR's with different samples because you don't know which virus it is? furthermore you must have specific primers for the virusses you suspect the patient is infected with. Am i totally wrong? the after you've run PCR, then what do you do? you have an amplified virus genome, but don't you need to do some sequencing to identify which exact virus the patient has? In other words how does the identification of a virus with PCR work?

  9. This is virally funny and educative at the same time……can't believe I have so much information from cartoons

  10. Queria achar um canal assim aqui no Brasil, mas não achei, agora to aprendendo um pouco inglês também, parabéns!

  11. Like this comment if your in high school or middle school and had to either copy a link or scan the Q code to get to this video

  12. Antivirals are a virus version of antibiotics. What antivirals do is they prevent them from reproducing upon entering a cell.

  13. Viruses can infect each other so when they put dna into a cell instead of reproducing the virus that binded onto the cell it reproduces the viron’s virus.

  14. You already uploaded this remember one of your old videos we already talked about viruses no you're are noob

  15. I'm trying to find out how the viruses mutate or how a new strain is created. I'm no doctor or biologist, just a curious engineer. So a virus makes copies of himself and then when it mutates all copies mutate too in the same new version because being copies of the original virus they are kinda entangled (ya know, like the subatomic particles) and they can communicate? — that would make them intelligent entities (and I'll tell you how to solve the problem)! What if n copies of a virus in the same organism (say inside Joe-6-pack) mutate in n different new versions — would Joe been carrying n different strains of the original virus?

  16. Antibiotics be like
    Bonsai!!!!!!!!!!!!!!!!!!!!!
    Phages be like
    Ok so we need to attack this bacteria and the other ones there good ones so ignore them

  17. The worst virus, called the Computer Virus, infects the battery cells (get it) of a computer. This virus has caused the break down of many species of computers, killing 1000 of unsuspecting computers each week. It slows down the metabolism of a computer. It can even cause errors in the core memory system.

  18. I try so hard to source my videos from a variety of places…but time after time your videos have the right info at the right level. Thank you!

  19. Hello Amoeba Sisters again! It is me-Professor Beata Yacura-Your scientist!🧬🧩👩‍🔬🔬🧪🧫💉🦠
    I have a favorite virus. My favorite type of virus is the Bacteriophage! Why? Because they are helpful viruses. Scientists are using them for medicine to kill mutated bacteria!🥳🎉🎊
    I have a virus too! It is a harmless virus. It is called a wart. A wart is a virus that looks like a bump. In order to get rid of them fast, you can take a freeze away wart remover. Talk to you later!👋

    P.S. I have a question, I do know and you told us that viruses are smaller then body cells and bacteria. But if the immune system recognizes and fights bacteria and viruses, why the helper T lymphocytes or helper T cells don’t recognize HIV?🤔

  20. if the amoeba sisters are both cells and were examining viruses at a close range, then how didnt either one get infected by any viruses trying to reproduce?

    this lore is W H A C K

  21. 1.How does ebola alive when virus are considered non living things
    2.And how do viruses die? When like i said it is non living things

    3.Do you mean they just swicth to deactivate mode? For ex. The virus is outside the body for years,, do they just deactivate?
    4. Or they can be activated again after of long years of being deactivated?

  22. So do I understand correctly that the lytic cycle is how a standard influenza virus replicates, while the lysogenic cycle is how a retro-virus does it? In the former, some of the cell's ribosomes are hijacked and make virus genes/proteins exclusively, while in the latter, the virus dna is inserted into the cell's normal dna?
    Is it known how an external trigger causes a (virus) gene to be expressed to make a protein/RNA? For example, I've read methylation is the epigenetic tool to keep a gene in the 'off' position, but there are proteins (ex. SIRT) that are doing the monitoring?

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