Viruses (Updated)

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!


  • Amoeba Sisters

    This topic is now an Unlectured Series topic! 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.

  • Elisa Collins Zinda

    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!

  • Beata Yacura

    Hello Amoeba Sisters again! It is me-Professor Beata Yacura-Your scientist!๐Ÿงฌ๐Ÿงฉ๐Ÿ‘ฉโ€๐Ÿ”ฌ๐Ÿ”ฌ๐Ÿงช๐Ÿงซ๐Ÿ’‰๐Ÿฆ 
    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!๐Ÿฅณ๐ŸŽ‰๐ŸŽŠ
    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!๐Ÿ‘‹

    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 donโ€™t recognize HIV?๐Ÿค”

  • Roasted Carot

    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

  • Alucard Lord

    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?

  • Ben Nguyen

    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?

  • Nathan

    (This Gospel Tract is posted regardless of location and subject with discernment. The bible says Christians are called to proclaim the uncompromised and complete biblical gospel (Matthew 24:14, Matthew 28:19-20, Romans 1:16, John 12:48));

    Are you Deceived By Church/Man's Sinful Ways, Vain Theologies, Sciences, Politics, Entertainment, etc?
    False/Demonic Religions, Evolution/Atheism, rapture, easy believe gospel, one modern pastor, pagan holidays (Christmas-Easter, etc) ritual gatherings, worldliness (movies, sports, entertainment, pet idolatry, etc), unbiblical dress, uncovered women's heads, instrumental music, worship pastors, youth pastors, building centered faith, no Matthew 18 discipline, the tithe, heretical reformers…do not be deceived!

    Good News! Find Eternal Life…
    1) Faith… in the finished work of Christ (fully man, fully God) and His perfect sacrifice for sins (John 3:16)

    2) Repentance … turning from your fallen mind and ways to God's Holy ways. (Luke 13:3)

    3) Born again… you must be born of God's spirit to ever see eternal life. In this new life, He gives you a new heart and mind to then serve Him. (John 3:3, John 3)

    4 ) Holiness with obedience…. if your changed by God you WILL, as fruit, strive to leave all sin, worldliness, carnality and false ways (like man made religion) and obey His commands and be holy in all your ways. (1 Peter 1:15 / Hebrews 5:9 / Hebrews 12:14)

    5) Endure in your faith…. You MUST keep clinging to Christ via this saving faith to the end of your life, lest you fall away and have believed in vain. (Matthew 24:13, Matthew 10 and 1 Corinthians 15)

    This is the biblical gospel to eternal life. All without Christ will perish in their sins in Hell, and, ultimately, in the Lake of Fire, for all eternity. Never ending torment. (Romans 3:23, Hebrews 4:13, Romans 6:23, Revelations 20).

    The gospel is not just a religious action. No, it changes your entire life and you NO LONGER live for yourself but live to serve God alone. Jesus said you MUST worship God in spirit and truth. John 4:24

    (Critical & Essential Note: To understand God's word, you have to have faith that God exists (Hebrews 11:6); have to repent and open up to God. God will give you wisdom and understanding (and a new life/being born again) if you sincerely repent and let Him help you, for He is the Word of God (John 1:1). If you don't, you will NEVER understand it in God's truth. This statement comes from the experience of a true follower of Christ whose fruit is complete obedience to the full and complete Gospel and God, by God's standards in His Word. Only then will you truly understand the Word of God/Bible. This is part of the many reasons why knowing, having, and sharing the complete gospel is so important for the true followers of Christ, and for those who don't know the things of God, unbelievers, and false christian converts.)

    Most Christians will be denied by Jesus Christ because they don't follow all of what the bible says. If you love Jesus Christ, you keep his commandments (John 14:15). We are to obey God as fruit (Not works!!!) to show that we are His! (John 14:23, James 1:22, Luke 9:23, and many others).

    Man made traditions, man's flawed theologies, etc has made God's commandments of none effect/null/void/useless! (Matthew 15, Mark 7:3-9, Jeremiah 10:1-5, Deuteronomy 5:32-33, and many other verses). Repent, be born again, obey God in holiness/obedience, and endure until the end, or Jesus will deny you! (Matthew 7:13-29 (v.23)).

    Beware lest any man spoil you through philosophy and vain deceit, after the tradition of men, after the rudiments of the world, and not after Christ. (Colossians 2:8)

    There are some specific exceptions: In Luke 23:39-43 The thief on the cross saw Jesus as the Christ. The thief said that he was deserving of the death they were being put through, but said Jesus did not deserve it at all. He saw that he was deserving of death and changed his mind about himself, that he was a sinner and deserved what he was getting. Jesus, in His grace and mercy, forgave this thief and, in turn, the thief was given eternal life. (And Jesus said unto him, Verily I say unto thee, Today shalt thou be with me in paradise. (Luke 23:43)) Likewise, when someone who is going to perish or has admitted they were sinners and called out to Jesus to forgive them, He will forgive them if they really mean it. God knows the heart and thoughts of every man. (Matthew 9:4)

    And Jesus said unto him, Verily I say unto thee, Today shalt thou be with me in paradise. (Luke 23:43)

    HOWEVER: There is no excuse if someone has (or has had) access to the bible in one way or another (Americans, Europeans, anyone having access to the internet, physical bible, etc). God expects all those who have such resources to use them to gain more understanding of Him and His Word, etc. NO EXCUSES! God knows both the inside and outside of a person. He knows all of your heart and all of your ways. Because of this situation, if we donโ€™t obey, we will have our portion with the unbelievers, and that is ultimately in the lake of fire. (Read Luke 12) So do not practice sin, or this will be your destination.

    God has no pleasure in the death of the wicked (Ezekiel 18:23, 32, Ezekiel 33:11); why die when you can be forgiven and follow God in every facet of your life and live for eternity in God's Kingdom? God is not willing that anyone should perish, but come to repentance, and live (2 Peter 3:9). But you still have a choice….

    Bottom line: You are either righteous and walking with God or wicked following satan, the devil. (1 John 3). You will either live for all eternity with Christ because you lived for God and endured until the end, or perish in eternal torment in hell, then the lake of fire because you did not follow God when you had been given the opportunity to have faith in the death and resurrection of Christ (That Christ is God, died for you), repent and change your mind and ways to God's ways, have received a new heart and mind to serve God in every facet of your life, obey God in holiness, and endure until the end. God will be the just and perfect judge of all this. So repent and live for God so you can live for eternity with Him in His Heavenly Kingdom, will you? The exceptions do apply; God is also merciful. God's word cannot contradict itself, for it is inspired and breathed by God Himself (2 Timothy 3:16). God cannot contradict Himself. He is not the author of confusion (1 Corinthians 14:33), nor can He lie (Numbers 23:19, 1 Samuel 15:29, Psalm 89:35, Hebrews 6:18).

    If you repent (and are seeking assistance), looking for more information, visit and
    Read your bibles with good, biblical discernment! That's the most important thing! Obey The Gospel, Read Godโ€™s Word, ask God to help you, discern, judge biblically and living godly according to His Holy Word (etc)!

    (Note: No replies to the replies to this comment will be given. You may contact us via email on our web pages. Thank you for your time reading this.)

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