Meiosis: Where the Sex Starts - Crash Course Biology #13

Hank gets down to the nitty-gritty about meiosis, the special type of cell division that is necessary for sexual reproduction in eukaryotic organisms.
References:
faculty.clintoncc.suny.edu/fac...
www.genome.gov/Glossary/index...
www.sumanasinc.com/webcontent/...
sun.menloschool.org/~dspence/b...
Table of Contents
1) Homologous Chromosome Pairs 2:10
2) Primary Oocytes 3:30
3) Primary Spermatocytes 3:30
4) Meiosis 2:59
5) Interphase I 4:04
6) Prophase I 4:37
a) Crossover 5:05
b) Recombination 5:05
7) Metaphase I 7:53
8) Anaphase I 8:05
9) Telophase I 8:19
10) Prophase II 8:57
11) Metaphase II 9:23
12) Anaphase II 9:28
13) Telophase II 9:32
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[@mn7804]

I find it funny that instead of having a picture of john, they just filmed him standing there, silently, not moving for like a good 30 seconds.

[@RTS64]

Ya your right lol

[@dorianalacitignola7700]

+Nissa Smith I WAS DYING WHEN I SAW THAT LOLOLOL

[@queenskyster8768]

+Nissa Smith He didn't even blink!

[@aljan6]

+Nissa Smith i died when he said "I'm way better in assasins creet than him" xDDD

[@sdurairaj8094]

Moueies

[@pacandpal3]

i like how he brings his brother on just to roast him on his genetic traits .

[@queenskyster8768]

Anyone else was expecting John to be all like "Hey!"

[@Tybeuf]

+DrunkOnAnime yep i was so disappointed he didn't argue back or something

[@queenskyster8768]

IKR!

[@aliatee1942]

Yup.

[@alexshi1679]

QueenJoou This one is Hank not John.

[@pshwow]

Alex Shi John is in the beginning lol..they filmed him for like 30 seconds just still

[@DizzyDior12]

Good luck to everyone who has finals this week. *cries quietly into textbook at **2:35**am*

[@andrescelano4179]

EOC tomorrow kms

[@Macwithdachiknstripz]

+Dizzy Lizzie I have my Biology Final tomorrow morning :( I hope you did well!

[@andrescelano4179]

Ashton Bailey rip you

[@toooydoeur]

Bio keystones tomorrow

[@andrescelano4179]

TheCrazyNintendoMan ! mario galaxy

[@JKONNN]

110% relying on your mitosis and meiosis vids to pass bio.

[@thesilverdealer7193]

Juzzy K big facts

[@jinjekang4300]

For those who say these videos helped them pass a grade. I mean sure, thanks to the videos you guys passed and we are very grateful for his videos, BUT give some credit to yourself. Even if you did not get that passing grade, you did something fewer and fewer people do nowadays: trying your best and taking the initiative. YOU took the time and effort to watch the videos and CHOOSE to learn! That kind of determination and diligence is admirable and very commendable! :D

[@vanxssaisaac]

You've taught me so much more than my teacher ever has. Thank you so much for saving my grades.

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Sameee

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Vanessa Isaac

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( ͡° ͜ʖ ͡°)

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gotta love horribly underfunded yet mandatory education systems lololollolo

[@conchiludovice9002]

I HAVE AN EXAM IN 30 MINUTES AND IM CRAMMING ALL THIS INFORMATION INTO MY BRAIN BECAUSE I DIDNT LEARN ANYTHING FROM MY TEACHER WISH ME LUCK!!!!!!!!!!!!!!!!!

[@greennitricoxide2706]

how'd you do?

[@faithsheppard886]

how did it go?

[@glennmatthews758]

U good?

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I'm guessing it didn't go too well lmao

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How'd u do?

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WE NEED TEACHERS LIKE YOU IN SCHOOLS!!!

[@ZeeGhost713]

Ms Kate be careful what you wish for for all you know he might make us make a project on it, your partner has to watch the video with you, partner has to be opposite gender, has to bring model home and show you parents how it happened (0_0)

[@missunknownps3]

who else got an exam tomorrow? lol

[@defaultmesh]

missunknownps3 meeeee!!! biology to be exact, about mitosis and meiosis to be exact

[@NaturalGirlForChrist]

yes bio lab final :(((((

[@cafe_jazz_7836]

love that profile picture missunknownps3

[@anuraghooda8439]

missunknownps3 I have biology exam tomorrow.

[@Shadyroze]

It's midnight and I have an entire semester exam tomorrow hah

[@puralucid]

You are saving my career as a biologist.

[@imnew2nm324]

I'm a BIO teacher, and I review these because they are so much faster than going back to the text.

[@sanjanaj5055]

Cramming for a test tomorrow! This is so helpful! Teachers take two days to finish what he did in like 10-11 min

[@a1egua881]

I'm also cramming in a study session for tomorrow's test

[@sanjanaj5055]

This video helped me so much!! study sessions help too,but i missed mine

[@squidneythesquid2487]

Sanjana Jothimurugan I'm doing this 20 minutes before my biology exam

[@rafaelavila9571]

Sanjana Jothimurugan i bet you failed

[@notava6601]

nah G they take like a week at my shitty public school

[@TheLucyOlivia]

The only reason i'll pass biology is because of these videos

[@EnglishProgects]

Preach

[@davidcheese1032]

Lucy Olivia these are making up a chunk of my AS revision thank you so much Hank

[@thegone7]

OMG! These videos are really good, I used to be suck at science, but these videos are a godsend. Comment if you agree.

[@rachelsmith2755]

Lucy Olivia same

[@nickfamous]

Lucy Olivia same

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Such Crash Course. Much Science. Very Biology. So Green Brothers. Wow.

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much doge

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Amaze

[@annsuya_8364]

Bamboozle

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Such 2014

[@christophersalem7080]

imagine how hard it was for john to just stand still and have to listen to hank

[@alecmcleod3306]

I dare you to watch from 0:33-0:42 at half speed and not think about how Hank sounds drunk

[@reecedr98]

Dude, you are a legend

[@maxe381]

I just did this...and THIS is how I imagine him at a party, wasted, trying to science... LOL

[@ashleighs8483]

I died laughing lol!

[@markopolo8910]

LMAO! Thank you!

[@abhishekagrahara8248]

especially when he sais ughhhh duuuuuuude

[@nataliea7858]

I’ve watched this so many times that it’s finally starting to make sense

[@MdmERM]

I come back to this video every few years when I find myself needing a reminder about this process. Thanks Hank

[@whatsinaname7289]

6:50 John doing a mannequin challenge 4 years before it was a thing!!😂😂😂😂😂

[@VyxtheBat]

@@ZeeGhost713 WTFFFFFFF

[@Tybeuf]

Comment and like if you think Crash Course should do Physics

[@hwaner1]

Totally #Trump2016

[@NehaPd]

+Tyler Goodchild (tg228) Crash Course Physics is now available!

[@marsboy12]

Contagion Dwayne Johnson?

[@angelojustinezaraspe9214]

Yess

[@anya2885]

Yes

[@xBustedHeart]

if you were my teacher I'd be getting an A ++++++++++++++++ in biology

[@ogMonty21]

tru!

[@sweetummi123]

***** ikr..... i wish

[@LehoainamNam216]

Vc

[@jennamontanaa]

Hoainam Le gmfdv

[@Kebinwmiles]

***** seriously doubt you would get an "A ++++++++++++++++" since that is an absurd grading scale that a normal instructor wouldn't use. smh

[@ShiNoKuroTsuki]

You explain this much better and much more comprehensible than my teacher. And English isn't even my mother language...

[@SorryIdrinkCoffee]

same hier

[@eldjibheryr3546]

i'm doing a summer semester online with no classroom interaction, just READ THIS CHAPTER AND LEARN IT. thank you, hank, for teaching me biology.

[@lakengross6777]

Can you do Punnet Squares and Proababiltiy of Genetics/heredity?!?

[@Nick-yg9ql]

+Laken Gross they did it, in a video about DNA

[@glennmatthews758]

Punnet squares aren't that difficult to understand...

[@riya3930]

Watch their heredity video, they talked about it really distinctively

[@walkinginthesun17]

I would have failed history and biology in college if it weren't for you guys! Thank youu so much! these videos are awesome and perfect for procrastinators like myself!

[@KamixSam]

I wasn't aware that my epic assassins creed skill came from genetics

[@JulianLopezMasterRace]

Samuel Sargunam Completely unrelated but... Clannad =

[@KamixSam]

Julian Lopez Clannad is amazing!

[@nightravenalchemist]

Samuel Sargunam Well apparently it does now.

[@wenbenz]

Samuel Sargunam He could be genetically predisposed to video games, which allows him to get better at video games faster.

[@avishekdutta3310]

Clannad Afterstory💕

[@Bobbiethejean]

"I'm better at Assassin's Creed than he is..." Oh Hank, please. never change.

[@matingood5723]

do we love how john didn't blink at all during that 15 seconds.

[@TheFlash9333]

learned more in 11 minutes than what my bio teacher could do in 6 weeks

[@Euphoricbryanna]

lmfao. i wish this guy was my teacher. he's so funny

[@chopinfrederic5040]

My Bio teacher would beg to differ

[@analiesengelsman63]

Note to students: don’t cram 30 minutes before an exam! Not that I’m speaking from personal experience or anything....

[@bugrajatt]

I feel the weirdest deja vu watching this again for my upper division molecular genetics class. Feels like I'm in 10th grade AP biology again. 😅

[@guyu96]

Hank you do the best "Aww Dude" on this planet!! 00:41

[@idunnowhatimdoin]

So when I eat popcorn, I'm basically swallowing plant sperm?

[@andrewsugrue2170]

idunnowhatimdoin Thanks for ruining the movies for me...

[@isabellagill-gomez7745]

idunnowhatimdoin if you're allergic to pollen then you're allergic to plant sperm

[@ZipZapityZone]

It is plant sperm!!!!!!

[@Kebinwmiles]

idunnowhatimdoin that's deep bro

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when you have a bio final tmrw and your internet connection is being a shthead frkng hate this. arghhhh

[@Shyguy33Games]

cringe

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oOf

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he makes biology sound good

[@AeliaReadsBooks]

this will come in handy for my bio exam thanks,Hank

[@momokokami2771]

Why is this guy getting 122 dislikes... ._. ? Hes helping us and its explains it well. Why dislike?

[@stigfox]

This entire channel is an amazing addition to text books and lectures! Amazing detailed overviews that really help organize everything in my brain-space. Much love and thanks for these videos!

[@samanthataylor1761]

"trash Brown puff" 😂 😂 😂 😂

[@wild23oo]

Right

[@user-kt7ni3dn1s]

This is how im getting through the AP Bio exam lol

[@TheEmmaporium]

Влад Кузь SAAAAMMMMEEEEE

[@hufflepuff487]

Влад Кузь SAME

[@RacsoNagem]

Влад Кузь AP? This is my normal year 12 exam!

[@Mmla19]

Oscar Megan yeah, AP means advanced placement, meaning you can take this as a 9th grader

[@user-kt7ni3dn1s]

AP Bio as a 9th grader? My AP Bio teacher told me that she had one freshman take it but he dropped out after a month. Its just not something that your average 8th grade science class can prepare you for.

[@alyssavu1302]

Shout out to the Assassin's Creed reference hahahah

[@KaguraShinihimeMartinez]

+Alyssa Vu Nothing is True

[@danotheparsnip]

Everything is permitted

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Requiescat en pace

[@jagjotsingh7129]

+Alyssa Vu shout out to them getting me through genetics

[@margot8525]

That wasn't a reference lol

[@kaynine9022]

Can i just give you some appreciation for actually making me enjoy AND understand science. You have been saving my academic career for 7 months now.

[@antredevers9490]

Sir you have saved me this semester in my Biology course. Thanks so much for entertaining and understandable videos.

[@itaidagan1]

It's really confusing when he says "there's your mother's version lined up right next to your father's version" when the entire process is happening in a single person, it almost sounds like it's happening in an embryo, and it's not.

[@purpleagentpeanut9969]

You have 23 pairs of cromosomes, half of those pairs are from your dad, the other from your mom

[@katethegreat4918]

Yeah, I was confused about that at first too

[@yahiakhaled253]

Ikr

[@davidh3205]

Dude I know this was 3 years ago but can you explain this? I cannot wrap my head around what he's saying - it doesn't add up logically

[@kikesemore7045]

Wait, this guy isn't John Green? I THOUGHT HE WAS JOHN FOR THE LONGEST TIME.

[@iffshahjaffery5432]

This is his younger brother, Hank Green! XD

[@tanyakorotiuk7176]

dude, same here, i just found out a few weeks ago, when in one video i saw both of them...

[@slinkkkcrown6061]

Lol

[@greennitricoxide2706]

keep up

[@kimvaughan2140]

ha ha ha

[@ArvoDes]

This is probably the most useful channel on youtube, thank you so much

[@glennmatthews758]

6:04 I love the way he says that, the inflection of his voice.

[@yuven437]

I have "finals" in biology on monday! So damned stressed out! Thank you crash course! can you do a series on math next? :D

[@abcbassabc]

atheistfromnorway AP Bio?

[@yuven437]

Kreeky ?

[@abcbassabc]

atheistfromnorway Just wondering if you were also in ap bio because that's when our ap test is.

[@yuven437]

well I doubt it, never heard of AP bio. I have "biology 1". What does AP mean?

[@abcbassabc]

atheistfromnorway Don't I look foolish. It's advanced placement: essentially, a high school course that teaches at a college level. If you pass the exam at the end of the year, you get college cred.

[@a.j.digiovanni3489]

Wow, in all my biology education through high school I was never informed that only one of the daughter cells of meiosis becomes an actual egg cell. Thanks for that tidbit, good sir!

[@TotalNoobAtEverythin]

I learn perfectly fine in class, I just like going over things once more with a different view/explanation. I love watching Crash Course videos about stuff I already know

[@alexism5860]

Going on 30+ hours of studying for SAT bio and mitosis/meiosis still always get me the animations are very cute btw

[@A_A828]

Damn it, even with CrashCourse I don't get this stuff. I'm in college studying psychology now, and thought I would look this stuff back up as I never got it completely in high school even though I really liked biology, but yeah... Everything is so mixed up and complicated when it comes to DNA replication/meiosis/mitosis, I just keep missing stuff and getting confused.

[@patricksteele1161]

Get out some flash cards, when ever he says something you don't know or understand, make a flash card for it and look up the definition. There is a lot of stuff, and it requires lots of reading, watching videos, and studying to get it down.

[@A_A828]

Thanks man, I'll give it a go

[@ShashankParsewar]

You could always try any exercises online

[@mandycarter2559]

Go to MasteringBiology for practive quizzes, activities, videos ...... I'm studying psychology too and it helps ;)

[@lunamoonlune]

It's really fast paced, but I found that taking out a notepad and writing notes, pausing the video, as he says the important info makes the whole video make a whole lot of sense! Then you just watch the video again and you understand everything he says.

[@Bigbangrdbst]

You should make a physics page

[@JKchick62]

Omg L :D...and yes I agree a physics page should be made.

[@MrPerfectBob]

***** thermodynamics is a part of physics.. are you high

[@unite5870]

Quantum mechanics is physics -_-

[@LightninLi2ard]

What are these comments XD

[@Bigbangrdbst]

i don teven remmber writing this -_-

[@senadonkor2228]

Lol. Omg, you're Hank green? This legit just made my day and I was all like, "Did he say John? Wait, is that John Green?" OMGGGGGGGGGG. John Green is my favorite author

[@theGuilherme36]

+Sena Donkor Yeah haha, I also didn't know that (until some days ago)

[@ariannakraljic6237]

The fact that he brings up Doctor Who in almost every video makes my day

[@SamtheSlushy]

6:50 "john is stuck with this trash brown puff"

[@TropicalChris]

You're better at Assassin's Creed? You mean you can press the X button faster than him during the cut scene? lol

[@peterp-a-n4743]

Really, how is it even possible to be bad at Assassin's Creed?

[@danielcollison6161]

Peter P-a-n Mashing the attack button and never blocking, not running into hiding places. NOT COLLECTING EVERYTHING!

[@Someone-sq8im]

"My mad Assassin's Creed skills" That's a learned trait

[@9dash]

Bruh, its a joke.

[@FreddyG687]

LOVE the way this guy explain the process, Great Job Bud!

[@solanalawson7700]

I've re-watched this like 3 times and every time he starts the video with "REPRODUCTION" I'm still surprised and then I have to explain to my family what I'm watching

[@wild23oo]

Can you check me too i an biologist

[@susied377]

Thank God CrashCourse biology exist or i might fail my class. Honestly, all the visuals are awesome and its just way more interesting than a boring slide show and taking notes.

[@mariahleigh2001]

bless your soul, I was falling asleep watching a bunch of drawings on a black screen, you make this a lot more easier to pay attention to

[@ewongton8257]

I have learned more and come to a better understanding of biology watching 5 episodes of crash course in comparison to 12 hours of school which had only left me clueless. Hank Green, you are seriously a student's lifesaver. Thank you.

[@lorenzosorrell1566]

I'm studying this stuff for my next test

[@Jemdawg1000]

I have a quiz on this tomorrow. Thank you for making it clear!!!

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My biology teacher showed our class this channel my sophomore year of high school. Now im a freshman in college and i still watch this. It's so easy to learn from this!

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THANK YOU THANK YOU THANK YOU!!!! I`m almost crying tears of joy, because something I used to watch just for fun now is very useful for studies AND FUN. Sending all my love to the people of Crash Course

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I'm so impressed with these crash course videos! I find them incredibly useful for bio english and history. S/O to whoever is funding these and making them publicly available

[@shokoshokoshoko73]

Science _is_ a miracle! Nature and science are the most amazing miracles of all because they are happening all the time and not just once or twice, that's what's so amazing about the world :)

[@ganeshramg.s7715]

cool videos . john is humorous in his way of expressing , making my interest in biology more.

[@husahallo]

I teach chemistry/biology/physics in Norway. The book the school use can be pretty bad at explaining things like miosis in a good way. Their English skills are not good enough to understand this type of scholar English. So to make class more interesting and what they are learning easier to understand I use crash courses where I do a Norwegian voice over in class. They love it, and they really get it! Thank you so much for making awesome videos!

[@trevorvoss5892]

I'm a physicist who recently began work in the field of Bio-Medical Engineering. These videos have helped me SO MUCH. I cannot thank you enough.

[@thomash3949]

You are saving an IB student right now

[@aaronohnemus3446]

You, sir, have been instrumental in my understanding of biology. I would simply like to thank you!

[@UniverseEarthSpirit]

I have never been able to get over how amazing meiosis is. Great Video!

[@Galdeater]

Good luck for Friday guys

[@avaMonkeyGaming]

actually true on the doctor who thing...

[@dinosaurrawl6800]

Thank you for always having CC!

[@xuemi2079]

you made it pretty easy nd interesting .. like im planning to watch all ur videos in the summer holiday !

[@maggieissecretlyaunicorn]

this was a perfect review for my quiz tomorrow, thank you!

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hey you have the same name as me and i also have a quiz over this tomorrow, and im also in the phandom are you me did i just meet my clone

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maggie r i've always wanted a secret clone nice 😂

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HOLY TARDIS ON GALLIFREY! OKAY, OKAY, YOU FRIKEN MENTIONED DOCTOR WHO AND I OFFICIALLY LOVE YOU FOR ALL OF YOUR REGENERATIONS! :D

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***** Sigh...

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creepy fangirl

[@TDeclinator]

You a creepy nigga!

[@CatrinL]

I'm sorry you don't understand my happiness. Doctor Who brings me so much joy, sadness, and a new appreciation for everyday life. I apologize for your lack of knowledge about Doctor Who.

[@TDeclinator]

Actually i watch doctor who, and for your information, im the same as you.

[@hayasulaiman6559]

Thank you crash course! You guys know how to make it fun and interesting

[@KathrinaMahabir]

This helped me out so much, i can't thank you enough for these videos

[@thoughtsfromahead]

I think I may have found a pretty notable mistake (This is genuine confusion & care, because I'm in an intro college bio course right now, and I just used this video to fully understand how meiosis works and it is a source of variation in sexually reproducing organisms). At 8:44, Hank says "That is the end of [Meiosis I]. We now have 2 haploid cells, each with 23 double chromosomes..." Wouldn't that make them diploid? The cells aren't haploid until they have split again, at the end of Meiosis II. I could be wrong, or you guys could be using haploid to mean something else. Just thought I'd weigh in.

[@utvota]

As long as they remain attached at the centromere they are considered to be one chromosome and therefore they are Haploid.

[@thoughtsfromahead]

But the definition of "haploid," when referring to haploid/diploid and not a "haploid number," is one copy of all the genetic information needed instead of two. Even if they are attached at the centromere, it's two copies of the info

[@thoughtsfromahead]

Right before meiosis II, the cells are technically tetraploid. Then, they are diploid. Then, they are haploid.

[@utvota]

thoughtsfromahead The ploidy refers to the number of chromosomes not chromatids. Until the chromatids separate they are considered to be one chromosome. So even if they have copied themselves the chromosomes are not considered to be diploid until after they are separated at the centromere.

[@thoughtsfromahead]

utvota Ah, that makes sense. The technical definitions of chromosomes and chromatids can get tricky! Diploidy then would mean two copies of the DNA as separate chromosomes. Not a mistake then!

[@paulhunter2524]

dude cut the cute graphics i got a test in like 30 seconds smh

[@fishjohn014]

Hahaha I know right

[@loidastellitavera4308]

+Paul Hunter this is the most amazing thing in the world literally

[@AdamBlogz]

Thanks for the lovely introduction , went of full volume in library

[@jrjon738]

I'm still watching this in 2017! Thanks for the great work!

[@christylennon350]

I'm not sure if this is all that accurate. In oogenesis, Meiosis I is completed on the day of ovulation and produces two daughter cells-a large one called the secondary oocyte and a much smaller one called the first polar body. The polar body ultimately disintegrates. It is merely a means of discarding the extra haploid set of chromosomes. The secondary oocyte proceeds as far as metaphase II, then stops. If it is not fertilized, it dies and never finishes meiosis. If fertilized, it completes meiosis II and casts off a second polar body, which disposes of one chromatid from each chromosome. The chromosomes of the large remaining egg then unite with those of the sperm. Therefore, it should have been 2 polar body and 1 egg. :P

[@jamell3133]

Christy Liem hmmm no he's right!

[@ilanmalkin1466]

Christy Liem the polar body produced in meiosis 1 does split again to form 2 polar bodies. So you get a total of 3

[@sarar9817]

My friends and I use this for our biology classes since our teacher sucks...haha.

[@HeyThereYouAre718]

Very nice video, thanks! :) There is also a crossover between X and Y at the telomeres, at pseudoautosomal regions (PAR), which are homologous in X and Y.

[@wild23oo]

Check me

[@Sara-yr4kk]

bless your soul hank green you are helping me survive my degree. thank you, truly

[@michellemartin6581]

Without CrsshCourse, I would probably have a C in my Bio H class >__

[@GemPiece]

of all the mitosis/meiosis videos on youtube, these are the only ones that keep my attention and make it so easy for me to understand. great job

[@KaWulfe]

this video is like 6 years old but oh my god bless you guys LIFE SAVERS

[@antoniovalencia9835]

I just learned what my professor couldn't teach me in 2 weeks, in 11 minutes. Thank you crash course.

[@loneenvoyyale5259]

Straight up have my exam in an hour and some minutes

[@UPandUNDER]

Any1 else from uk got their biology GCSE tomorrow?

[@samratnakar1648]

+UPandUNDER lmao bio mock tomorrow

[@damanstar]

You legit get me through year 12 biology

[@rachelhuang_sdg]

You are a wonderful lecturer!!!! Fantastic! Many thanks and please keep producing high quality videos like this❤️

[@wild23oo]

V beautiful can you watch me in my channel 😊😊😊😊