Eukaryopolis – The City of Animal Cells: Crash Course Biology #4

Eukaryopolis – The City of Animal Cells: Crash Course Biology #4

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This is an animal. This is also an animal. Animal. Animal. Animal carcass. Animal. Animal.
Animal carcass again. Animal. The thing that all of these other things have
in common is that they’re made out of the same basic building block: the animal cell. Animals are made up of your run-of-the-mill eukaryotic
cells. These are called eukaryotic because they have a “true kernel,” in the Greek.
A “good nucleus”. And that contains the DNA and calls the shots
for the rest of the cell also containing a bunch of organelles. A bunch of different kinds of organelles and
they all have very specific functions. And all this is surrounded by the cell membrane. Of course, plants have eukaryotic cells too,
but theirs are set up a little bit differently, of course they have organelles that allow
them to make their own food which is super nice.  We don’t have those. And also their cell membrane is actually a
cell wall that’s made of cellulose. It’s rigid, which is why plants can’t dance. If you want to know all about plant cells,
we did a whole video on it and you can click on it here if it’s online yet. It might not
be. Though a lot of the stuff in this video is
going to apply to all eukaryotic cells, which includes plants, fungi and protists.   Now, rigid cells walls are cool and all, but
one of the reasons animals have been so successful is that their flexible membrane, in addition
to allowing them the ability to dance, gives animals the flexibility to create a bunch
of different cell types and organs types and tissue types that could never be possible
in a plant. The cell walls that protect plants and give them structure prevent them from
evolving complicated nerve structures and muscle cells, that allow animals to be such
a powerful force for eating plants. Animals can move around, find shelter and
food, find things to mate with all that good stuff.  In fact, the ability
to move oneself around using specialized muscle tissue has been 100% trademarked by kingdom
Animalia.>>OFF CAMERA: Ah! What about protozoans? Excellent point! What about protozoans? They don’t have specialized muscle tissue.
 They move around with cillia and flagella and that kind of thing. So, way back in 1665, British scientist Robert
Hooke discovered cells with his kinda crude, beta version microscope. He called them “cells”
because hey looked like bare, spartan monks’ bedrooms with not much going on inside. Hooke was a smart guy and everything, but
he could not have been more wrong about what was going on inside of a cell.  There is
a whole lot going on inside of a eukaryotic cell. It’s more like a city than a monk’s
cell.  In fact, let’s go with that a cell is like a city. It has defined geographical limits, a ruling
government, power plants, roads, waste treatment plants, a police force, industry…all the
things a booming metropolis needs to run smoothly.  But this city does not have one of those
hippie governments where everybody votes on stuff and talks things out at town hall meetings
and crap like that.  Nope.  Think fascist Italy circa 1938.  Think Kim Jong Il’s- I mean, think Kim Jong-Un’s North Korea, and
you might be getting a closer idea of how eukaryotic cells do their business.
  Let’s start out with city limits. So, as you approach the city of Eukaryopolis
there’s a chance that you will notice something that a traditional city never has, which is either
cilia or flagella.  Some eukaryotic cells have either one or the other of these structures–cilia
being a bunch of little tiny arms that wiggle around and flagella being one long whip-like
tail.  Some cells have neither. Sperm cells, for instance, have flagella, and our lungs
and throat cells have cilia that push mucus up and out of our lungs.  Cilia and flagella
are made of long protein fibers called microtubules, and they both have the same basic structure:
9 pairs of microtubules forming a ring around 2 central microtubules. This is often called
the 9+2 structure. Anyway, just so you know–when you’re approaching city, watch out for the
cilia and flagella! If you make it past the cilia, you’ll encounter
what’s called a cell membrane, which is kind of squishy, not rigid, plant cell wall,
which totally encloses the city and all its contents.  It’s also in charge of monitoring
what comes in and out of the cell–kinda like the fascist border police. The cell membrane
has selective permeability, meaning that it can choose what molecules come in and out
of the cells, for the most part.   And I did an entire video on this, which you
can check out right here. Now the landscape of Eukaryopolis, it’s important
to note, is kind of wet and squishy. It’s a bit of a swampland. Each eukaryotic cell is filled with a solution
of water and nutrients called cytoplasm.  And inside this cytoplasm is a sort of scaffolding
called the cytoskeleton, it’s basically just a bunch of protein strands that reinforce
the cell.  Centrosomes are a special part of this reinforcement; they assemble long
microtubules out of proteins that act like steel girders that hold all the city’s buildings
together. The cytoplasm provides the infrastructure
necessary for all the organelles to do all of their awesome, amazing business, with the
notable exception of the nucleus, which has its own special cytoplasm called “nucleoplasm”
which is a more luxurious, premium environment befitting the cell’s Beloved Leader. But
we’ll get to that in a minute.   First, let’s talk about the cell’s highway
system, the endoplasmic reticulum, or just ER, are organelles that create a network of
membranes that carry stuff around the cell. These membranes are phospholipid bilayers.
The same as in the cell membrane. There are two types of ER: there’s the rough
and the smooth. They are fairly similar, but slightly different shapes and slightly different
functions. The rough ER looks bumpy because it has ribosomes attached to it, and the smooth
ER doesn’t, so it’s a smooth network of tubes. Smooth ER acts as a kind of factory-warehouse
in the cell city. It contains enzymes that help with the creation of important lipids,
which you’ll recall from our talk about biological molecules — i.e. phosopholipids
and steroids that turn out to be sex hormones. Other enzymes in the smooth ER specialize
in detoxifying substances, like the noxious stuff derived from drugs and alcohol, which
they do by adding a carboxyl group to them, making them soluble in water. Finally, the smooth ER also stores ions in
solutions that the cell may need later on, especially sodium ions, which are used for
energy in muscle cells.   So the smooth ER helps make lipids, while
the rough ER helps in the synthesis and packaging of proteins. And the proteins are created by another typer
of organelle called the ribosome. Ribosomes can float freely throughout the cytoplasm
or be attached to the nuclear envelope, which is where they’re spat out from, and their
job is to assemble amino acids into polypeptides. As the ribosome builds an amino acid chain,
the chain is pushed into the ER. When the protein chain is complete, the ER pinches
it off and sends it to the Golgi apparatus. In the city that is a cell, the Golgi is the
post office, processing proteins and packaging them up before sending them wherever they
need to go. Calling it an apparatus makes it sound like a bit of complicated machinery,
which it kind of is, because it’s made up of these stacks of membranous layers that
are sometimes called Golgi bodies. The Golgi bodies can cut up large proteins into smaller
hormones and can combine proteins with carbohydrates to make various molecules, like, for instance,
snot.   The bodies package these little goodies into
sacs called vesicles, which have phosopholipid walls just like the main cell membrane, then
ships them out, either to other parts of the cell or outside the cell wall. We learn more
about how vesicles do this in the next episode of Crash Course. The Golgi bodies also put the finishing touches
on the lysosomes. Lysosomes are basically the waste treatment plants and recycling centers
of the city. These organelles are basically sacks full of enzymes that break down cellular
waste and debris from outside of the cell and turn it into simple compounds, which are
transferred into the cytoplasm as new cell-building materials. Now, finally, let us talk about the nucleus,
the Beloved Leader.  The nucleus is a highly specialized organelle that lives in its own
double-membraned, high-security compound with its buddy the nucleolus.  And within the
cell, the nucleus is in charge in a major way.  Because it stores the cell’s DNA, it
has all the information the cell needs to do its job. So the nucleus makes the laws for the city and orders the other organelles around, telling
them how and when to grow, what to metabolize, what proteins to synthesize, how and when
to divide. The nucleus does all this by using the information blueprinted in its DNA to
build proteins that will facilitate a specific job getting done.  For instance, on January
1st, 2012, lets say a liver cell needs to help break down an entire bottle of champagne.
The nucleus in that liver cell would start telling the cell to make alcohol dehydrogenase,
which is the enzyme that makes alcohol not-alcohol anymore. This protein synthesis business is
complicated, so lucky for you, we will have or may already have an entire video about
how it happens. The nucleus holds its precious DNA, along
with some proteins, in a weblike substance called chromatin. When it comes time for the
cell to split, the chromatin gathers into rod-shaped chromosomes, each of which holds
DNA molecules. Different species of animals have different numbers of chromosomes. We
humans have 46. Fruit flies have 8. Hedgehogs, which are adorable, are less complex than
humans and have 90 Now the nucleolus, which lives inside the
nucleus, is the only organelle that’s not enveloped by its own membrane–it’s just
a gooey splotch of stuff within the nucleus. Its main job is creating ribosomal RNA, or
rRNA, which it then combines with some proteins to form the basic units of ribosomes. Once
these units are done, the nucleolus spits them out of the nuclear envelope, where they
are fully assembled into ribosomes. The nucleus then sends orders in the form of messenger
RNA, or mRNA, to those ribosomes, which are the henchmen that carry out the orders in
the rest of the cell. How exactly the ribosomes do this is immensely
complex and awesome, so awesome, in fact, that we’re going to give it the full Crash
Course treatment in an entire episode. And now for what is, totally objectively speaking
of course, the coolest part of an animal cell: its power plants!  The mitochondria are these
smooth, oblong organelles where the amazing and super-important process of respiration
takes place. This is where energy is derived from carbohydrates, fats and other fuels and
is converted into adenosine triphosphate or ATP, which is like the main currency that
drives life in Eukaryopolis. You can learn more about ATP and respiration in an episode
that we did on that. Now of course, some cells, like muscle cells
or neuron cells need a lot more power than the average cell in the body, so those cells
have a lot more mitochondria per cell.   But maybe the coolest thing about mitochondria
is that long ago animal cells didn’t have them, but they existed as their own sort of
bacterial cell. One day, one of these things ended up inside
of an animal cell, probably because the animal cell was trying to eat it, but instead of
eating it, it realized that this thing was really super smart and good at turning food
into energy and it just kept it. It stayed around. And to this day they sort of act like their
own, separate organisms, like they do their own thing within the cell, they replicate
themselves, and they even contain a small amount of DNA. What may be even more awesome — if that’s
possible — is that mitochondria are in the egg cell when an egg gets fertilized, and
those mitochondria have DNA. But because mitochondria replicate themselves in a separate fashion,
it doesn’t get mixed with the DNA of the father, it’s just the mother’s mitochondrial DNA.
That means that your and my mitochondrial DNA is exactly the same as the mitochondrial
DNA of our mothers. And because this special DNA is isolated in this way, scientists can
actually track back and back and back and back to a single “Mitochondrial Eve” who lived
about 200,000 years ago in Africa.   All of that complication and mystery and beauty
in one of the cells of your body. It’s complicated, yes. But worth understanding. Review time! Another somewhat complicated
episode of Crash Course Biology. If you want to go back and watch any of the stuff we talked
about to reinforce it in your brain or if you didn’t quite get it, just click on the
links and it’ll take you back in time to when I was talking about that mere minutes ago. Thank you for watching. If you have questions
for us please ask below in the comments, or on Twitter, or on Facebook. And we will do
our best to make things more clear for you. We’ll see you next time.

100 thoughts on “Eukaryopolis – The City of Animal Cells: Crash Course Biology #4

  • Rosie Pena Post author

    Eve comes from East Africa and we are all related to her! So essentially, we are all African Americans! (if you live in America).

  • Abraax Post author

    Carl at 8:29

  • Candy Jones Post author

    Who else got a test In a few hours and have not studied

  • DiBBagE Post author

    Soo basically we are all related

  • ShadyDinoCollector Post author

    OUTDATED ALERT!!! Verify recent research indicating a fathers mitochondria CAN be inherited!!

  • Roulev Poo Post author

    What if a plant can actually dance…:D

  • flashkid wacky Post author

    You guys are very helpful, now I am confident for my Long/Chapter/Major Test tomorrow.

  • The Stig Post author

    Why does the nucleus remind me of Jaba the hutt? 🤔

  • Danny Post author

    This dude sure has some political opinions

  • Kimberly Moraes Walker Post author

    Hank, don't plant cells have both a cell wall and a cell membrane, whereas animal cells have only a cell membrane and not a cell wall?

  • MyLifeForAuir87 Post author

    "Hippie" city's with voting and democracy lol

  • yeetyeetskeet Post author

    when you're not smart enough to understand what is going on in the video

  • P. Z. Post author

    It sounds like one cell is selfsustainable, if it is provided with food.

  • Legend player Post author

    Why you be my bio teacher

  • gia chuan dang Post author

    vessicle or vesicle ?

  • Adriana Cardoso Costa Post author

    Tem esse vídeo dublado em português??

  • Izzy Teets Post author

    Crash course was the only reason I was able to pass AP Bio

  • Eminon Nyeipahu Post author

    Your explanation is so fast.

  • Sarah Kuzell Post author

    Is the Golgi Apparatus responsible for my runny nose?

    I'm a gonna go for a walk now, and probably regret it later.

  • n.jewells Post author

    2019 anyone?

  • Khardellen Post author

    I wish you guys could show more videos of the process instead of still images. It’d help to visualize things

  • Kool Killer664 Post author

    No offence but you speak very fast

  • Kiểm Duyệt Ad 5276 Post author


  • jackson Post author

    for all of you watching this because your bio teacher's hungover and sent you on a webquest, he talks about the "cell is like a city" thing at 2:20. you're welcome

  • Angelo Serrano Post author

    I like the old videos of this guy the cute emoticons

  • Yami Assasin Post author

    a week before my AP Bio test. Thank you

  • retosius Post author

    wait a minute, THIS GUY DOES SCISHOW!

  • Ritvik Singh Post author

    Put it a .75 speed he seems high, .5 speed hes a crackhead

  • Adam Shiny Post author

    I’m not here because my bio teachers bad. I’m just here cause I’m a bad student.

  • Kaley Sperling Post author

    Anyone else hungry

  • john sinha Post author


  • Abigail Andrade Post author

    I really did not feel Hank as he was enthusiast

  • E B Post author

    this for boss bitches….for money making bitches……

  • Pew DiePie Post author

    Man i am just tired of making so many videos

  • Saead Borji Post author

    Dude!!! poetic and literary devices ( exaggeration, metaphor, allusion, etc.) are profanities and blasphemies in science literature. Do avoid them.

  • UB-157 Post author

    الخلية حقيقية النواة اشبه بالمدينة
    لها حدود جغرافية محددة وحكومة و مصانع طاقة و طرق و معامل لمعالجة النفايات و شرطة و صناعات

  • UB-157 Post author

    السوط مكون من الياف بروتين ليفية طويلة تسمى مايكوتيوب

  • UB-157 Post author

    الغشاء الخلوي جدار طري يغلف المدينة و كل محتوياتها و مسؤول عن مراقبة ما يدخل الى الخلية و ما يخرج منها
    وهو اشبه بشرطة فاشية
    و لديه قدرة الاختيارية النفاذية
    اي انه يستطيع اختيار اي جزيء يدخل او يخرج من الخلية

  • UB-157 Post author

    اراضي مدينة حقيقيات النواة رطبة و طرية مليئة بمحلول من الماء والعناصر الغذائية تسمى السايتوبلازم
    وداخل السايتوبلازم يوجد بناء يسمى هيكل الخلية (اشرطة بروتين تدعم الخلية)
    والجسيمات المركزية اجزاء خاصة من هذا الدعم وهي تجمع مايكروتيوبلز. طويلة من البروتين
    يعني الجسم المركزي يعمل كالروافد الفولاذية اللي تثبت كل مباني المدينة معاً
    ويوفر السايتوبلزم البنية التحتية الضرورية لقيام كل العضيات بوظائفها المدهشة باستثناء النواة! لان لديها سايتوبلازم خاص بها يسمى البلازم النووي

  • UB-157 Post author

    النواة لديها سايتوبلازم خاص بها يسمى البلازم النووي البيئة المرهفة اللائقة بقائدة الخلية المحبوبة النواة

  • UB-157 Post author

    الشبكة الاندوبلازمية "نظام الطرق السريعة"
    عضيات تقوم بانشاء شبكة اغشية تنقل المواء في ارجاء الخليةشبكة الاغشية هذه هي ليبيدات فوسفورية ثنائية الطبقة كما في الغشاء الخلوي
    هناك نوعان من الشبكة الانبوبلازمية خشنة وملساء وهما متماثلان لكن هناك اختلاف في شكلهما ووظائفهما
    الخشنة : وعرة لان الريبوسومات متصلة بها تساعد في تخليق وجمع البروتينات التي يتم صنعا بواسطة عضي اخر هو الريبوسوم
    الملساء : لا تتصل بشيء تعمل كمستودع في مدينة الخلايا تحوي على انزيمات تساعد في انشاء ليبيدات مهمة
    وتخزن ايونات في محاليلها قذ تحتاجها الخلية خاصة ايونات الصوديوم التي تستخدم للطاقة في الخلايا العضلية

  • UB-157 Post author

    الريبوسومات تطفو بحرية عبر السايتوبلازم او بالالتصاق بالغشاء النووي الذي خرجت منه
    وظيفتها تجميع الحمض الاميني الى بوليببتيد
    وعندما يبني سلسلة حمض اميني سوف تُدفع السلسلة الى الغشاء الاندوبلازمي
    وعندما تكتمل سلسلة البروتين سوف ياخذها الغشاء الانبولازمي الى جهاز كولجي

  • UB-157 Post author

    في المدينة جهاز الكولجي هو المكتب البريدي
    حيث يعالج البروتينات و يحزمها قبل ان يرسلها الى حيث يجب ان تذهب
    يتكون جهاز كولجي من اجسام كولجي
    اجسام كولجي هي اكداس من طبقات غشائية
    تستطيع اجسام كولجي ان تقسم البروتينات الكبيرة الى هرمونات صغيرة + دمج البروتينات مع الكربوهيدرات لصنع جزيئات متنوعة كالمخاط

  • Velpex 124 Post author

    Anyone else cramming in last minute revision for a science exam?

  • Miss Jackson Post author

    This teacher is so funy! I love hem!!!!

  • KEV Post author

    I used to memorise my biology notes word by word. Now I watch Crash Course and the knowledge automatically gets into my brain.

  • Gianni Ly Post author


  • younes maghnawi Post author

    The création of god

  • Ali L Post author

    This video was hugely helpful in preparing for my test!! Thank you so much!!


    watching this again i finally got it …

  • Salahuddeen Sha'ban Post author

    guys who's better:
    Crashcourse or FreeScienceLessons, i think crashcourse click if you agree

  • Semka7a Post author

    W I T H I N C E L L S I N T E R L I N K E D

  • Scared Camel Post author

    How do animal cells make their own glucose?

  • Red Manchester Post author

    Breakthrough? 🤘🤘

  • Red Manchester Post author


  • Raya Kelley Post author


  • Imama khattak Post author

    You did it so well🙋

  • Harvey Sun Post author

    Well, our cities are actually all cell cities.

  • Hannah - Post author

    i literally wrote "eukaryopolis" on my exam. as you can see i'm doing well rn

  • Jay Caliba Post author

    I came here to say that IDGAF about mitochondria is the powerhouse of the cell, Nucleus contains our genetic material called"DNA"🤣🤣🤣

  • 엄슬비 Post author

    it's really helpful to understand how works our cells!

  • flymasterA Post author

    Where does a cell store immaterial behavioral instinct programs?
    Do all of an animal's cells have the same instincts stored?
    Can learned habits become instincts?
    Can instincts be reprogrammed?
    Does the cell have a brain?
    Do plant cells contain behavior instincts, ex. Venus Flytrap?

  • flymasterA Post author

    So is science able to create the simple cell to create life? What animates the cell, making it alive? You talk like the cell has the complexity of an outhouse, but then you describe the metropolis complexity of the cell. Which is it? Simple or beyond comprehension?
    The survival of the cell depends on instinctive activities of both the cell and the animal it's in, and the survival of the animal means the survival of its cells. Where are these programs that rely on environment responses and timing? Sounds infinitely complex.

    Can you do a video explains cell activity and behavioral programming? Ex. Say a spider and a Venus flytrap, instinctive and reactive?

  • Travis M Post author

    "Which is why plants cant dance" Lel

  • Vektor Post author


    Animal cell

    Eukaryotic cells, with membrane ,organelles and nucleus containing DNA that calls the shots

    Animal, plants, fungi and protist

    Flexible and squishy membranes as oppose to plants, allowing the creation of cell, organs and tissue types

    Cell is like a city:

    On the surface:

    Microtubials: made of long protein fibers: Cillia (tiny arms like in lungs and throat pushing the mucus up) and Flagella (whip-like tail like in sperms), Protozoans, move with Microtubials instead of muscle tissue

    Membrane: Selective permeability: monitoring coming in and out like boarders


    Cytoplasm: water+nutrients

    Cytoskeleton: scaffolding made of protein strands, Centrosomes: infrastructures

    Endoplasmic Reticulum (ER): network of membranes like a highway system

    The smoother parts of ER are like factories:

    containing enzymes (proteins) producing lipids,

    detoxifying substances by adding carboxyl to make them soluble in water,

    storing ions like Sodium used for energy

    The rougher parts of ER have Ribosomes attached to them:

    Synthesis and packaging of proteins

    Ribosomes: float freely, assemble amino acids into Polypeptides pushing the protein chain into ER where it's bitten off and sent to Golgi Aparatus

    Golgi: made of membranous layers: the post office for packaging proteins, cutting them into hormones, combining them with Carbs to make molecules

    Vessicles: the packages with Phospholipid walls

    Lysosome: waste treatment and recycling, sacks containing enzymes breaking down cell waste into building material

    Mitochondria: the power plant where respiration takes place, fuels converted to Adenosine Triphosphate (ATP) which is the currency

    They were separate bacteria that animal cells absorbed and kept, and they still act as their own organisms with their own DNA, they exist in the egg and doesn't mix with sperms DNA during fertilization


    The leader

    Contains DNA and has all the information and instructions

    Has a double membrane

    Nucleoplasm (is like Cytoplasm)

    Nucleolus at the center: creates Ribosomal RNA+proteins=Ribosomes

    Messenger RNA: carry the orders to Ribosomes

    Chromatin: web-like substance that holds DNA molecules, upon cell division they gather into rod-shaped chromosome, humans have 46

  • Mᴀɴɪ ᴋᴀɴᴛᴀɴ Post author

    not so brief

  • Sean McEuen Post author

    My brain hurts every time I watch one of these.

  • Arshiya Kharel Post author

    Is this useful for a level ocr biology

  • Phantom 1254 Post author

    Αυτό το βίντεο βοήθησε πολύ και σας ευχαριστώ πολύ για την αγάπη του καναλιού σας

  • SirBanana Post author

    This video is now banned in North Korea.

  • Mandolin Brown Post author

    they spelled vesicles wrong. 6:38

  • Randy Gerke Post author

    You mixed up centrioles with centromeres which are found on chromosomes.

  • Jull ana Post author

    Wish I have your brain

  • Fantasy Post author

    I didn't know that thing about mitochondria! That's truly amazing. Btw finally someone who managed to explain all the organelles properly! I've never understood them in high school…

  • Luis Zepeda Post author

    Me : breathes
    Nobody :
    Literally nobody :
    Hank Green : makes 16 minute video about what breathing is and who invented it

  • alishah noorani Post author

    I've been studying for too long. the delusion has hit. I'm crying laughing at john green, hank green and pinto bean. send help.

  • Abby the Dancer Post author

    Thank you! You're in the credits of my project!

  • Cartosa Post author

    Omg my life is saved

  • Nicholas Dye-shaffer Post author

    What's up nerds my teacher is having me watch this and complete a paper instead of actually teaching us.

  • Hello Hi Post author

    In smooth ER 5:34 isn't suppose to be calcium ions instead of sodium ions?

  • Yung Ulcer Post author

    I hate my wife

  • Mohamed Lehachi Post author

    thank you for this

  • Cassidy Varg Post author

    fortunately, my biology professor is awesome and knows how to describe things in an easy to understand way however, there's only so much you can teach in 45min

  • yahirfortniteking Post author

    Bruh Im in 7th grade why am I learning this

  • Andrew Caddel Post author

    bruh moment

  • Roger Snow Post author

    How does the Golgi app. know how to fold molecules of protein into specific shaped molecules? I mean, how does it know what it is doing? How does it know what shape proteins it needs, how does it know how to fold those shapes? How does it fold those shapes? How does it know what it is doing, is there a brain inside the Golgi? How does it know what it needs to do? It just seems so complex, how can something that is not even its own cell, know how and when to do all these things?

  • Jacob MtCastle Post author

    Thank the good lord I found this I have an exam tomorrow and my Biology professor sucks

  • Emmanuel Abraham Post author

    Learning new things about cell it's very fun.
    Mabey a little bit.🤔

  • Daniel Culver Post author

    he looks like dwight shrute

  • RAMY Post author

    The comment section is getting a bit repetitive… we get it your biology teacher sucks. Mine is actually quite good but I like to see other people teach it Incase she missed anything.

  • J McG Post author

    Hank, what's written on your hand? Lol i think it's really cool that one of my idols has to write things on his hand to remember them just like I do.

  • Sara Mammedova Post author

    Hello l want have a doctor becouse l like this job an this job its fantactic amazinnng👏💛😅

  • ashwini ranade Post author

    Every sentence he utters has a whole episode explaining that sentence..

  • blob fish Post author

    my ancestors fought for there life’s and where the best of there generations, and yet i’m here just watching a video and doing nothing in my life, does it get better?

  • Savannah Rudolph Post author


  • Dragon Pearl Post author

    Ah yes. This has aged well.

  • Zara M Post author

    picture of burger
    Hank: animal carcass
    Me: gags

    idk why but that changed my opinion on burgers omg

  • the rush 27 Post author

    Me watching this for a test tommorow 😰

  • *cough* It's BTS Post author

    Watch at 0.75 speed to be able to process information.
    You’re welcome

  • Natalie Mak Post author

    So technically are mitochondrial DNA the same in all humans if they came from one single mother Eve?

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