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
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!!!!!!!!!!!!!!!!!
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)
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!
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.
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
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!
Haploid cells means a cell with one pair of chromosomes .When meiosis1 occurs a diploid cell containing 2 homo-pairs of chromosomes ( pair from mum,pair from dad) divides making 2 daughter cells each containing 1 pair of different chromosomes .
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!
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!
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
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
CrashCourse I have a question re: meiosis. What's really tripping me up is: 1. at 2:29 you show homologous chromosome pairs. There are only 22 pairs (44 chromosomes). Is this found in all body cells with the 23 pair being the sex chromosome? Or is this found in the specialized cells that make sperm and egg cells (spermatocytes/oocytes)? 2. (Based on your answer to question 1, if yes to the first part of the question) Is the missing pair from the homologous chromosome pairs, the 23rd and 24th chromosome which codes for sex cells the "XX" (women) and the "XY" (men)? 3. (Based on your answer to question 1, if yes to the second part of the question) Is the missing pair from the homologous chromosome pairs, the 23rd and 24th chromosome which codes for sex cells the "XX" (women) and the "XY" (men)? 4. Does meiosis only occur on the 23rd and 24th chromosomes of the specialized spermatocytes and oocytes?
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.
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!
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
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.
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!
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
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.
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 :)
You have finally inspired me after an entire semester of biology to be wowed by the processes inside of our body and cells. Thank you for bringing humour and logic to this complicated topic. Lets hope the exam goes well tomorrow ;)
The first cytokinesis in meiosis is also called interkinesis since it takes the place of a second interphase. some profs/teachers want you to use that term instead of cytokinesis.
I'm proud to say that I learned about meiosis in high school and I am now 38 years OLLLDD and I still remembered most of this! Came for a brush-up because I'm starting IVF treatment next month. Also Wow Hank's voice has changed a lot since 2012!
diploid cell splits into half twice, produces 4 separate cells that are genetically distinct. primary oocytes (diploid) primary spermatocytes interphase: all key players replicate, nuclear envelope disintegrates. centrosomes and microtubules prophase 1:centrosomes go to poles, each chromosome is linked to its duplicate copy. cross over and homologous recombination. each double chromosome lines up with its homolog (one from one from dad).they trade sections of DNA. 1 pair of chromosomes doesn't undergo cross over or recombination (sex c'somes XY) after meiosis 1: 2 haploid cells (23) from 1 single diploid cell (46) we have 4 cells with 23 chromosomes.
It's actually a common misconception that X and Y chromosomes have nothing to do with each other during crossing-over. In fact they CAN get tangled and exchange genes, and because they aren't homologous this can result in some really interesting situations in which some of the Y chromosome's DNA can cross over to an X chromosome during spermatogenic (sperm-making) meiosis. This X chromosome may then fertilise the ovum (which always has one X chromosome), and what you get is a fertilised ovum with two X chromosomes, but with some Y chromosome DNA too (even though there's no Y chromosome in the cells). Usually, this doesn't affect anything, but there's a not-small chance that the gene that crosses over to the X chromosome will be a gene called "SRY-1", or "sex-determining region-1". This is the "trigger" for the production of testes, the genes for which are actually already on the X chromosome. This causes a zygote with two X chromosomes and no Y chromosome to develop testes (though, they cannot produce sperm because they lack the other parts of the Y chromosome), and thus develop as partially or wholly phenotypically male-typical. This is one of the many kinds of **intersex condition**, and the specific name for this condition is "SRY-1 Positive de la Chapelle's Syndrome". Intersex people make sex determination WAY more complicated than just XX/XY, especially since chromosomes are overruled by hormone levels later in the gestation. So, it's important to remember that this is a part of development that's FREQUENTLY skipped over, but really shouldn't be because it's very important!
My teacher doesn't even teach us in class he just makes us read the textbook, and the textbook is really hard to understand. I learn better by hearing it so I FINALLY understand after the 2 months of "learning" mitosis and meiosis.
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
Around 8:50 you mean diploid right? and not haploid because you said 23 double chromosomes each cell meaning 46 so Diploid... Can someone clear this up for me?
+ROMAN HANG LIMBU Nah, its haploid. Diploid cells have 23 PAIRS of double chromosomes while haploid has 23 TOTAL. Double chromosome just means two chromatids. DISCLAIMER IF THIS IS WRONG IM HERE FOR THE SAME REASON YOU WERE :)
+Gauri Sathish Yeah but if its haploid in that stage then in the final process where 4 cells are produced it's going to have 11.5 chromosomes which just doesn't sound right? right?
+ROMAN HANG LIMBU I got confused as well, but then found this: www.quora.com/Why-are-the-cells-at-the-end-of-Meiosis-1-and-Meiosis-2-said-to-be-haploid and a diagram: upload.wikimedia.org/wikipedia/commons/5/54/Meiosis_diagram.jpg
+ROMAN HANG LIMBU A double chromosome refers to a chromosome composed of two sister chromatids. At the end of meiosis one, you have 23 double chromosomes, no homologous pairs, and thus they are haploid.
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.
Love Hank's videos. The only thing he got wrong on this one was at the very end. The creation of a new life IS a miracle! Sure, it's fun to study the miracle through science, but the miracle is a miracle all it's own. Science is just the study of it. :)
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.
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.
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.
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.
It's more than a miracle, it's even _more than science_ - it's *Nature*. Science is just the most precise and certain way for intelligent lifeforms who find themselves in a natural environment to observe the wonderful things that arise out of Natural order.
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.
Thank you soo much your videos really helped me so much Everyone who wants to learn i tell them to watch you hands down the best learning channel on the internet :D
I LOVE this. Thank you for 'speaking my language'. Your videos are so helpful! Three chapters of my textbook didn't help me as much as these videos. Keep doin' what your doin'. It is much appreciated!
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.
Ya your right lol
+Nissa Smith I WAS DYING WHEN I SAW THAT LOLOLOL
+Nissa Smith He didn't even blink!
+Nissa Smith i died when he said "I'm way better in assasins creet than him" xDDD
Moueies
i like how he brings his brother on just to roast him on his genetic traits .
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
110% relying on your mitosis and meiosis vids to pass bio.
Juzzy K big facts
You've taught me so much more than my teacher ever has. Thank you so much for saving my grades.
Sameee
Vanessa Isaac
( ͡° ͜ʖ ͡°)
gotta love horribly underfunded yet mandatory education systems lololollolo
Good luck to everyone who has finals this week. *cries quietly into textbook at **2:35**am*
EOC tomorrow kms
+Dizzy Lizzie I have my Biology Final tomorrow morning :( I hope you did well!
Ashton Bailey rip you
Bio keystones tomorrow
TheCrazyNintendoMan ! mario galaxy
Anyone else was expecting John to be all like "Hey!"
+DrunkOnAnime yep i was so disappointed he didn't argue back or something
IKR!
Yup.
QueenJoou This one is Hank not John.
Alex Shi John is in the beginning lol..they filmed him for like 30 seconds just still
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!!!!!!!!!!!!!!!!!
how'd you do?
how did it go?
U good?
I'm guessing it didn't go too well lmao
How'd u do?
You are saving my career as a biologist.
I'm a BIO teacher, and I review these because they are so much faster than going back to the text.
WE NEED TEACHERS LIKE YOU IN SCHOOLS!!!
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)
The only reason i'll pass biology is because of these videos
Preach
Lucy Olivia these are making up a chunk of my AS revision thank you so much Hank
OMG! These videos are really good, I used to be suck at science, but these videos are a godsend.
Comment if you agree.
Lucy Olivia same
Lucy Olivia same
I come back to this video every few years when I find myself needing a reminder about this process. Thanks Hank
Such Crash Course.
Much Science.
Very Biology.
So Green Brothers.
Wow.
much doge
Amaze
Bamboozle
Such 2014
Cramming for a test tomorrow! This is so helpful! Teachers take two days to finish what he did in like 10-11 min
I'm also cramming in a study session for tomorrow's test
This video helped me so much!! study sessions help too,but i missed mine
Sanjana Jothimurugan I'm doing this 20 minutes before my biology exam
Sanjana Jothimurugan i bet you failed
nah G they take like a week at my shitty public school
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.
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!
imagine how hard it was for john to just stand still and have to listen to hank
I’ve watched this so many times that it’s finally starting to make sense
Comment and like if you think Crash Course should do Physics
Totally #Trump2016
+Tyler Goodchild (tg228) Crash Course Physics is now available!
Contagion Dwayne Johnson?
Yess
Yes
I dare you to watch from 0:33-0:42 at half speed and not think about how Hank sounds drunk
Dude, you are a legend
I just did this...and THIS is how I imagine him at a party, wasted, trying to science... LOL
I died laughing lol!
LMAO! Thank you!
especially when he sais ughhhh duuuuuuude
Can you do Punnet Squares and Proababiltiy of Genetics/heredity?!?
+Laken Gross they did it, in a video about DNA
Punnet squares aren't that difficult to understand...
Watch their heredity video, they talked about it really distinctively
if you were my teacher I'd be getting an A ++++++++++++++++ in biology
tru!
***** ikr..... i wish
Vc
Hoainam Le gmfdv
***** seriously doubt you would get an "A ++++++++++++++++" since that is an absurd grading scale that a normal instructor wouldn't use. smh
who else got an exam tomorrow? lol
missunknownps3 meeeee!!! biology to be exact, about mitosis and meiosis to be exact
yes bio lab final :(((((
love that profile picture missunknownps3
missunknownps3 I have biology exam tomorrow.
It's midnight and I have an entire semester exam tomorrow hah
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.
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.
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
Right before meiosis II, the cells are technically tetraploid. Then, they are diploid. Then, they are haploid.
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!
I heard that too I was so confused
Haploid cells means a cell with one pair of chromosomes .When meiosis1 occurs a diploid cell containing 2 homo-pairs of chromosomes ( pair from mum,pair from dad) divides making 2 daughter cells each containing 1 pair of different chromosomes .
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!
bro coming back to this channel after a long time is amazing because its somehow even funnier than 12 year old me remembers it being
great stuff
You explain this much better and much more comprehensible than my teacher. And English isn't even my mother language...
same hier
This is probably the most useful channel on youtube, thank you so much
6:50 John doing a mannequin challenge 4 years before it was a thing!!😂😂😂😂😂
@@ZeeGhost713 WTFFFFFFF
I wasn't aware that my epic assassins creed skill came from genetics
Samuel Sargunam Completely unrelated but... Clannad =
Julian Lopez Clannad is amazing!
Samuel Sargunam Well apparently it does now.
Samuel Sargunam He could be genetically predisposed to video games, which allows him to get better at video games faster.
Clannad Afterstory💕
Why is this guy getting 122 dislikes... ._. ?
Hes helping us and its explains it well. Why dislike?
"I'm better at Assassin's Creed than he is..."
Oh Hank, please. never change.
lmfao. i wish this guy was my teacher. he's so funny
My Bio teacher would beg to differ
Sir you have saved me this semester in my Biology course. Thanks so much for entertaining and understandable videos.
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
learned more in 11 minutes than what my bio teacher could do in 6 weeks
Hank you do the best "Aww Dude" on this planet!! 00:41
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!
do we love how john didn't blink at all during that 15 seconds.
this will come in handy for my bio exam thanks,Hank
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
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.
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
CrashCourse I have a question re: meiosis. What's really tripping me up is:
1. at 2:29 you show homologous chromosome pairs. There are only 22 pairs (44 chromosomes). Is this found in all body cells with the 23 pair being the sex chromosome? Or is this found in the specialized cells that make sperm and egg cells (spermatocytes/oocytes)?
2. (Based on your answer to question 1, if yes to the first part of the question) Is the missing pair from the homologous chromosome pairs, the 23rd and 24th chromosome which codes for sex cells the "XX" (women) and the "XY" (men)?
3. (Based on your answer to question 1, if yes to the second part of the question) Is the missing pair from the homologous chromosome pairs, the 23rd and 24th chromosome which codes for sex cells the "XX" (women) and the "XY" (men)?
4. Does meiosis only occur on the 23rd and 24th chromosomes of the specialized spermatocytes and oocytes?
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.
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. 😅
I friken love crash course. I have a bio exam in two day and will be watching crash course that whole time.
he makes biology sound good
Going on 30+ hours of studying for SAT bio and mitosis/meiosis still always get me
the animations are very cute btw
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!
9:20 I don't think that's how you spell prophase...
Ella Tschebotarjew propahse
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
+Sena Donkor Yeah haha, I also didn't know that (until some days ago)
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.
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!
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
Christy Liem hmmm no he's right!
Christy Liem the polar body produced in meiosis 1 does split again to form 2 polar bodies. So you get a total of 3
6:04 I love the way he says that, the inflection of his voice.
I have "finals" in biology on monday! So damned stressed out!
Thank you crash course! can you do a series on math next? :D
atheistfromnorway AP Bio?
Kreeky ?
atheistfromnorway Just wondering if you were also in ap bio because that's when our ap test is.
well I doubt it, never heard of AP bio. I have "biology 1". What does AP mean?
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.
The fact that he brings up Doctor Who in almost every video makes my day
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 :)
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
I have a quiz on this tomorrow. Thank you for making it clear!!!
cool videos . john is humorous in his way of expressing , making my interest in biology more.
You have finally inspired me after an entire semester of biology to be wowed by the processes inside of our body and cells. Thank you for bringing humour and logic to this complicated topic. Lets hope the exam goes well tomorrow ;)
At 9:22, "Prophase" was misspelled..
The first cytokinesis in meiosis is also called interkinesis since it takes the place of a second interphase. some profs/teachers want you to use that term instead of cytokinesis.
I'm proud to say that I learned about meiosis in high school and I am now 38 years OLLLDD and I still remembered most of this! Came for a brush-up because I'm starting IVF treatment next month. Also Wow Hank's voice has changed a lot since 2012!
You should make a physics page
Omg L :D...and yes I agree a physics page should be made.
***** thermodynamics is a part of physics.. are you high
Quantum mechanics is physics -_-
What are these comments XD
i don teven remmber writing this -_-
diploid cell splits into half twice, produces 4 separate cells that are genetically distinct.
primary oocytes (diploid)
primary spermatocytes
interphase: all key players replicate, nuclear envelope disintegrates.
centrosomes and microtubules
prophase 1:centrosomes go to poles, each chromosome is linked to its duplicate copy. cross over and homologous recombination. each double chromosome lines up with its homolog (one from one from dad).they trade sections of DNA.
1 pair of chromosomes doesn't undergo cross over or recombination (sex c'somes XY)
after meiosis 1: 2 haploid cells (23)
from 1 single diploid cell (46) we have 4 cells with 23 chromosomes.
when you have a bio final tmrw and your internet connection is being a shthead frkng hate this. arghhhh
cringe
oOf
It's actually a common misconception that X and Y chromosomes have nothing to do with each other during crossing-over. In fact they CAN get tangled and exchange genes, and because they aren't homologous this can result in some really interesting situations in which some of the Y chromosome's DNA can cross over to an X chromosome during spermatogenic (sperm-making) meiosis. This X chromosome may then fertilise the ovum (which always has one X chromosome), and what you get is a fertilised ovum with two X chromosomes, but with some Y chromosome DNA too (even though there's no Y chromosome in the cells).
Usually, this doesn't affect anything, but there's a not-small chance that the gene that crosses over to the X chromosome will be a gene called "SRY-1", or "sex-determining region-1". This is the "trigger" for the production of testes, the genes for which are actually already on the X chromosome. This causes a zygote with two X chromosomes and no Y chromosome to develop testes (though, they cannot produce sperm because they lack the other parts of the Y chromosome), and thus develop as partially or wholly phenotypically male-typical. This is one of the many kinds of **intersex condition**, and the specific name for this condition is "SRY-1 Positive de la Chapelle's Syndrome".
Intersex people make sex determination WAY more complicated than just XX/XY, especially since chromosomes are overruled by hormone levels later in the gestation. So, it's important to remember that this is a part of development that's FREQUENTLY skipped over, but really shouldn't be because it's very important!
My teacher doesn't even teach us in class he just makes us read the textbook, and the textbook is really hard to understand. I learn better by hearing it so I FINALLY understand after the 2 months of "learning" mitosis and meiosis.
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
Shout out to the Assassin's Creed reference hahahah
+Alyssa Vu Nothing is True
Everything is permitted
Requiescat en pace
+Alyssa Vu shout out to them getting me through genetics
That wasn't a reference lol
bless your soul hank green you are helping me survive my degree. thank you, truly
Around 8:50 you mean diploid right? and not haploid because you said 23 double chromosomes each cell meaning 46 so Diploid... Can someone clear this up for me?
+ROMAN HANG LIMBU Nah, its haploid. Diploid cells have 23 PAIRS of double chromosomes while haploid has 23 TOTAL. Double chromosome just means two chromatids. DISCLAIMER IF THIS IS WRONG IM HERE FOR THE SAME REASON YOU WERE :)
+Gauri Sathish Yeah but if its haploid in that stage then in the final process where 4 cells are produced it's going to have 11.5 chromosomes which just doesn't sound right? right?
+ROMAN HANG LIMBU Yeah, I'm watching it again and I think he meant to say diploid.. So.. right.
+ROMAN HANG LIMBU I got confused as well, but then found this:
www.quora.com/Why-are-the-cells-at-the-end-of-Meiosis-1-and-Meiosis-2-said-to-be-haploid
and a diagram:
upload.wikimedia.org/wikipedia/commons/5/54/Meiosis_diagram.jpg
+ROMAN HANG LIMBU A double chromosome refers to a chromosome composed of two sister chromatids. At the end of meiosis one, you have 23 double chromosomes, no homologous pairs, and thus they are haploid.
ASSASSINS CREEEEED your officially my favorite person
this video is like 6 years old but oh my god bless you guys LIFE SAVERS
This is how im getting through the AP Bio exam lol
Влад Кузь SAAAAMMMMEEEEE
Влад Кузь SAME
Влад Кузь AP? This is my normal year 12 exam!
Oscar Megan yeah, AP means advanced placement, meaning you can take this as a 9th grader
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.
"trash Brown puff" 😂 😂 😂 😂
Right
Love Hank's videos. The only thing he got wrong on this one was at the very end. The creation of a new life IS a miracle! Sure, it's fun to study the miracle through science, but the miracle is a miracle all it's own. Science is just the study of it. :)
Without CrsshCourse, I would probably have a C in my Bio H class >__
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.
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.
Thanks man, I'll give it a go
You could always try any exercises online
Go to MasteringBiology for practive quizzes, activities, videos ...... I'm studying psychology too and it helps ;)
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.
I just learned what my professor couldn't teach me in 2 weeks, in 11 minutes. Thank you crash course.
I'm studying this stuff for my next test
You are saving an IB student right now
I have never been able to get over how amazing meiosis is. Great Video!
this was a perfect review for my quiz tomorrow, thank you!
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
maggie r i've always wanted a secret clone nice 😂
HOLY TARDIS ON GALLIFREY! OKAY, OKAY, YOU FRIKEN MENTIONED DOCTOR WHO AND I OFFICIALLY LOVE YOU FOR ALL OF YOUR REGENERATIONS! :D
***** Sigh...
creepy fangirl
You a creepy nigga!
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.
Actually i watch doctor who, and for your information, im the same as you.
It's more than a miracle, it's even _more than science_ - it's *Nature*. Science is just the most precise and certain way for intelligent lifeforms who find themselves in a natural environment to observe the wonderful things that arise out of Natural order.
6:50 "john is stuck with this trash brown puff"
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.
You have 23 pairs of cromosomes, half of those pairs are from your dad, the other from your mom
Yeah, I was confused about that at first too
Ikr
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
Thank you soo much your videos really helped me so much Everyone who wants to learn i tell them to watch you hands down the best learning channel on the internet :D
Your videos are the reason I am getting an A in my anatomy/physiology class! I am plan on getting my Master's at MSU as well! Thank you!
whats up with ridiculously similar science words? alkAnes/alkEnes osteoBlasts/osteoClasts mITosis/mEIosis???
Because they're more likely than not nomenclature for ridiculously similar things. How is this not abundantly clear?
also, it's easier to remember similar names for similar functions.
Hypotonic/Hypertonic 😭
I have finals this morning. So naturally, here I am. And thank you.
I LOVE this. Thank you for 'speaking my language'. Your videos are so helpful! Three chapters of my textbook didn't help me as much as these videos. Keep doin' what your doin'. It is much appreciated!
These videos are so great. Hank's always funny and he makes the topic interesting. This really helps with exams. Thanks Crash Course!
I'm still watching this in 2017! Thanks for the great work!
Wait, this guy isn't John Green? I THOUGHT HE WAS JOHN FOR THE LONGEST TIME.
This is his younger brother, Hank Green! XD
dude, same here, i just found out a few weeks ago, when in one video i saw both of them...
Lol
keep up
ha ha ha