Phases of Meiosis

[PleasedToBeHere1]

When i learned this at school it was all memorization of names and i understanded nothing. I wish i would have found this video earlier; my understanding is much better know.

[ToxiqueRosia]

Haha, thanks, watched this 30 minutes before my midterm today, great review of everything. ;)

[mpq357]

What software is this?

[MsWatcheverything]

Thank you !

[yukikohohoho]

what's the difference between centrosomes and centrioles??

[15danielss]

CENTROSOMES PEOPLE!!!

[justforfun22111]

heheh he called the chromosome a "purple dude"

[ajitmishra5968]

what's the need of dna replication at the first phase .why nature has devised such a step if the end result would have to be haploid cell which could be done even if no replication would have occured.

[rosiedamato96]

you can tell the procrastinators from the over-achievers in this bunch. over achievers say things like "exam in 4 days" and us procrastinators say things like "exam in 2 hours." PROCRAST4LYF

[carmodykc]

your videos are amazing, so easy to understand



[Spacehorse99]

14 people missed the like button...

[AhmedAyy1]

germs make gamets? DAFUK?

[ben10150]

@AhmedAyy1 germ cells. that does not mean the "Germs" that make us sick, germ cells are reproductive cells, sperm or eggs

[mickykiki1]

Exam in a few hours... hope this helps

[prognostics]

test tomorrow lets gooooo XD

[RegionalMisrea2010]

final in 19 hours..

[jeweliekimchi]

Hmm....8:00 pm, my parents want me to sleep before 11:00, bio test tomorrow....*Time to get some help from Khan Academy!*

[ItsChriswren]

27:18

That is all

[icetea751]

thank u

this is helpful 

[connyluckirby9]

Final in 12 hours xD

[TheJlc5696]

You could be an amazing teacher..!!

[kiathekitten]

Final tomorrow! I can do it! XD thanks to this help! :)

[MrAlphalpha]

Test in!9 hours

[MrAMoosvi]

Exam in 2 days..

[pandabearwhat]

thx imma acr my meiosis quiz now!!!

[ArTZaKalnw]

which program did u use to draw this?

[ttwizlerzz]

@ak2pacalypse haha!!! It does

[mazviebabie]

centrosomes are in plant cells and centrioles in animal cells

[milliepards96]

My bio teacher refers to those "little things" that generate the spindle fibers as centrioles, not centrosomes.

[umakemefeelthisway]

@milliepards96 : In the mitotis video, he did mention that the centrosomes contain the centrioles!

[MayraMacabre]

AP Bio final next week e__e gah. im SO glad our generation has internet...

[JuanLikesRice]

13 ppl has to watch this video for homework... one of em's me.. hope my teacher doesnt see this xD

[003Strawberry]

thank you!!

[eddabed2]

Mifosis?

[alexlovely17]

These videos are soooooo helpful

[Emcray1]

Gah... such a good teacher

[macracwhite]

OR does the chromosomes come and become parted from a one long chain of DNA?

[macracwhite]

how many DNA exists in a human body to make 23 pairs of chromosome?

[NeedSubscriptions]

I always watch these to prepare for tests. Thanks.

[HASSOON7112]

I LOVE YOU !!

[itsthat1dudeovrthere]

Finals are going to kiss my ass tomorrow. :D

[AimlessAmigo]

oops you corrected yourself nevermind

[AimlessAmigo]

Is it just me or do you start reffering to centrosomes by saying centromere somewhere in the middle?

[jennieatscake]

this man is a genius !

[CpShOcK123]

isn't it 46 chromosomes, not 43?

[natterLUVSu]

19:28 .... imememe. What?

[ShelIy456]

you're like the opposite of my AP bio teacher...U R PURE AWESOMENESSS! (:

[Skaldi3]

Best video for Mitosis/Meiosis nomination

[EaglesFastAndLow]

Khan Academy, the reason why professors everywhere will be out of a job.

[MrZOEBOII]

@EVERYBODY, Sal actually made a mistake in the ending! The end result of Meiosis two is 4 haploid cells, which he stated! Although he applied another constituent (another chromatid) in the final haploid cells. Once you've seperated your sister chromatids thats it! There should be only one chromatid in each gamete!! :)

[Hammerbeast51592]

final exam in two hours...

[ItsAriflex]

@Hammerbeast51592 Midterms

[sh3lieMa3]

youre awesome. thank u. :)

[ak2pacalypse]

This dude sounds like phil dunfy lol

[PbNewf]

i dont understand why my prof cant teach exactly like this lol...



[MarauderRaine]

Test in two hours. Thanks for being my study buddy. :)

[shaiban7]

i thought those poles during cell division are called "centrioles" and that dot in between the the chromosomes is called the "centromere"

[WhatTheFuckIsUpDoe]

@shaiban7 the dot between the chromosomes are the centromeres, the poles are microtubules. phaggot

[TazLuvsMuzic87]

I finally understand the difference between meiosis and mitosis completely! This is such a huge relief. Thank you Khan!!!! :D

[nhessell]

thank you, this helped me so much!

[junk11111111]

I got a test in two days and i've done the reading but watching this is like having a pro tutor study buddy to highlight the major points

[wakwas]

@junk11111111 i have a test on Wednesday too

[TheTdwpforever]

So, in the end, the only two chromatids cross each other leaving the small purple and small green?

[violin617]

Thank you very much =D ^-^

[a7xsoadchick]

I love these.. SO helpful.



[TheTdwpforever]

@a7xsoadchick Avenged sevenfold is good.

[foreverxundefined]

PMAT

[asdfiengf]

I cant get over how the certrisome on the right in prophase II looks like a dancing skeleton

[TheTdwpforever]

@asdfiengf Shietttt brah! it does.

[0955interactive]

11 people lost their jobs as a biology teacher

[1999pixidust]

@lychee159 yup i think ur right i just did lolz :)

[1999pixidust]

again.....seventh grade...... but i luv this vid... much nicer than my science teacher :):)

[TheTdwpforever]

@1999pixidust Because he doesn't feel the stress from fucking idiots such as us.

[1999pixidust]

@TheTdwpforever ya ikr?

[dadawg618]

i like the subtitles.......should add them in more often :D

[naten9]

Can we have an online class with you?

[fleshcookie]

just in case, during prophase 1, when Sal talks about genetic recombination (9:40) if you have a teacher like mine who requires all the littlest details, the point at which the crossing over occurs is called the "chiasmata"

[WDMinecraft]

piss - prophase

miss - metaphase

at - anaphase

toilet - telephase

[ananddullabh]

PMAT,

I Poop = prophase

on Mondays = Metaphase

And = Anaphase

Tuesdays = Telophase

[TristanIRL]

Telophase 1 looks like boobies with cleavage(furrows).

[policerip]

centroMeres are in the Middle of chromosomes. centroSomes Slide to the poles of the cell. hope it helped.

[iTotalNonsense]

:D awesome..

Its more clear now. thanks.

[JewishWarrior69]

@JTK12893 lmao you win this round

[Funkipotato]

LOL cleavage. That's the most hilarious metaphor for telophase/cytokinesis i have ever encountered.

[Ray93C]

PLs dnt move your mouse so much,,,!

[JewishWarrior69]

@JTK12893 disregard my last statement, was just trolling and now I feel bad lmao

[JTK12893]

@JewishWarrior69 LOL, funny cause i got a state ranking wtf did you get? come at me bro

[JewishWarrior69]

@JTK12893 stfu jewish whore

[JTK12893]

@JewishWarrior69 u mad?

[JewishWarrior69]

@JTK12893 come on me bro

[JTK12893]

@JewishWarrior69

..... what a HEAD!

[JewishWarrior69]

@JTK12893 judging by your horribly structured and poor grammar/spelling, are you sure you should be doing a subject like biology?

[ZacksGuitarCover]

Puerto-ricans = Prophase

Make = Metaphase

Awesome = Anaphase

Tacos = telophase

[anarjoshi]

Just to point out, at 1:45 he says we start off with 43 chromosomes but it's actually 46 chromosomes.

[zenoparodie]

@anarjoshi he says 23, per cell, so it makes sense

[lychee159]

10 people watch this after their tests

[jabp891]

This helped me a LOT

I was about to ask whether they were centromeres or centrosomoes but immediately after I started typing you corrected yourself. Even so, it's still really helpful!!

[alexpapas5]

Those 10 professors are definitely Jealous.

[nhtn91]

20:12 That one should be called Centrosome...not centromere :D

[KodierungHerz]

Leptotene, Zygotene, Pachytene, Diplotene and Diakinesis???

[Jearhby]

Im so glad you corrected yourself with centromeres and centrosomes!! OMG, I was just about ready to explode...

[ace814956]

what are they liberals

[BNoll4123]

Loved it these videos.They have helped my biology grade, and understanding of the subject matter immensely!!! Thank you for taking the time to write them they make a difference to those of us who study hard and sometimes still need a little help! I appreciate it!

[pictureskater]

comment

[fr33stylaa]

You speak with flare and passion for each subject that you make these videos for, thats what really makes you stand out to any other teacher in the classroom or on youtube. I'm halfway through the video, and motivated and entertained for the test that I have tomorrow. Things are really clear to me now, thanks to you.

[Rishabhsharma2703]

Thank you so much !

[blaze952]

@32gbworld exactly what im sayinn

[123cutestuff]

omg test tmr :S

[plborman]

CENTROSOME NOT CENTROMERES!!!!!!!!!!!!!!

[KJC0913]

This got me an A on my AP test. Thanks :)

[sjbaccay2]

you forgot the Interkinesis, which is a phase between Telophase I and Prophase II

[cutelilgaara]

Thank you so much, Bio-Jesus. You're are SUCH a life savior.

[pixelated111]

@cutelilgaara bio AND math jesus

[Akshayguptahere]

lolz,,,, BIO-JESUS :P :P :D :D :D

[TheTdwpforever]

@cutelilgaara Makes sense. Jesus, life saviour. 

[SoujaCow]

can someone please help me out here?

1. is meiosis the reproduction of sperm and egg cells or is it the reproduction of fertilised egg?

2. diploid cells have 2n normally 46, haploid cells have n normally 23 right?

3. are sex cells haploids?

4. wtf is a germ cell?

sorry i did watch the video ur a good teacher its jst that im too dumb=[

HELP ME

[Joeltanjunren]

@SoujaCow 1.Its the production of the spern or egg cell (depending on which sex you are).

Yep

Yep

A germ cell? I guess you meant Germline cell? Its basically the cell from your sexual organ which basically is your diploid cell which goes through meiosis to produce sperms or eggs!

Hope this helped though Im not really good at it myself =/

[SoujaCow]

@Joeltanjunren thanks alot for your answer man, it made things clearer, but one thing i still dont get. Since the germline cell contain chromosomes from both parents, then does that mean it is produced from a zygote? Chromosomes inside a germline cell stay alive since the start of our birth?

[AminorArpeggio]

In prophase I, where the cross over happens....that happens to all the pairs right? He only did it for one pair and for the rest of the video only that one pair was shown as having a little piece of each other. But ALL pairs have a little piece of each other right? He just didn't bother drawing it.

[Chocoalatte]

@AminorArpeggio It's a complete scramble. So some may be mixed up, some may not :)

[The0rangePanda]

Wait what happens if you choose to use division instead of multiplication?? Would it still work? Or would the exponents just cancel eachother out..???

[rhcpjohn444]

great video thank you so much it really helped put everything into perspective for me

[yinkiria]

for him anything is interesting jajajaja es lo máximo!! I speak Spanish and I understood everything that my teachers did not manage to teach in Spanish

so great

[MonaRocks09]

so in interphase s phase, lets say for humans, when the chromosomes duplicate, are there still 46 at this point or 92 now? I know it's stupid but I haven't properly learned :(

[OneVoiceOneDesire]

According to AQA - Thre are slight discrepencies between what you describe in a stage of Meiosis for example, You describe prophase as the stage of chromosome line up down the equator of the cell, AQA say this occurs during Metaphase... Now i'm really confused :S

[killwasgurl]

you saved me in my embryology class! a whole medical library couldnt explain these processes as well as you did!!

[smokey13500]

you are awesome, thanks a lot for taking your time to teach us. i really appreciate what you are doing. you are one of the best people who knows how to explain science, and your drawing is great. thanks for you help.

[piahjay]

Okay Im gonna Pass my class ....thanks!

[ryanbrunner24]

at 20:13 I think you mean centrosomes!

[thebigy05]

thanks heaps really great video!

[laxman875i]

Thank you so much!!! This helped so much!!!

[vincainjuly]

@laxman875i I liked this video very much. Please distinguish between centromere vs centrosome and centriole vs centrosome and correct video.

[vincainjuly]

@laxman875i I liked this video very much. Please distinguish between centromere vs centrosome and centriole vs centrosome and correct video.

[itsmeNicole1897]

YOU are an amazing teacher. I actually understood this lesson ! BIG thanks. :)

[palore96]

Even though our book in much less advanced that what was shown in the video (and so should be mine level in last year of middle school), I understood everything :) I love learning new things about biology, THANK YOU!

[Niecee44]

THANKKKKKKKKKKKKKKKKK YOUUUUUUUUU <3

[oxymoronicshai07]

this video is easy to understand.. saved me in my genetics class... :)

[madvick11]

i enjoy what i learn now..you are truly amazing :D you are THE BEST

[JTK12893]

thanks your awesome!

i remember PMAT as

Propose = prophase

Marry = metaphase

Aniversary = anaphase

(CYTO = kinda like SEPARate)

The end. = Telephase

thought might help some people! :)

[JewishWarrior69]

@JTK12893 i just remember four letters

[JTK12893]

@JewishWarrior69 well your a fuckin genius arnt ya

[vvbn7890]

@JTK12893 Nice, that does help thanks

[MrKsizzle01]

Amazing Teacher

[danielnives]

dis izz d most amazng vedio...n helped me 2 clear d doubts in my haphazard brain....

[WiltedGoddess]

@danielnives

To bad it didn't help you learn how to spell.

[SidTheBunny]

The left centrosome of prophase 1 looks like it has a face.

[sammynfhdpc]

I dont care if there are mistakes through out the video

becuase he teaches this WAY better than my bio teacher does

thank you!

[avonhill001]

Meiosis I reduces the ploidy level from 2n to n (reduction) while Meiosis II divides the remaining set of chromosomes in a mitosis-like process (division). Most of the differences between the processes occur during Meiosis I.

Interphase (2N) -> M1: P1 (2N), M1 (2N), A1 (2N), T1 (N....N), [cytokinesis 2(N)] -> M2: PII 2(N), MII 2(N), AII (2N), TII 2(N...N). [cytokinesis 4(N)]

In short:

Inter (2N) --> M1 (incl. cytokinesis): (2N) to 2(N) --> M2 (incl. cytokinesis): 2(N) to 2 (2N) to 4(N)

[mrpolishguy]

Can not thank you enough Sal, it's incredible how much difference a genuine, detailed explanation can make (as opposed to my lecturer who literally stands there reading slides). If I pass bio Im donating $100 =)

[CrimBlack]

It's a pitfall... to fall into! :D

[hpallinone7210]

at 20:09 I think you meant centrosomes, not centromeres =P Thanks for the awesome video, it's helping me in so many ways!

[TheSimplevietnam]

WARNING!!!!!! WRONG INFO

Germ cell ---> Meiosis I --> 2 x 2n cells --> Meiosis II ---> 4 x 1n cells

that's why you always have to learn with your thinking mind.

[schoolhockeymetal]

@TheSimplevietnam my biology textbook disagrees with you lol

[Dy699]

@TheSimplevietnam no after meiosis 1 we have 2 (1n) cells because the homologous chromosomes separated which means that the cells are now haploid.

Then in meiosis 2, the sister chromatids separate, and we end up with 4 haploid cells.

[DavidsVirtualSelf]

@TheSimplevietnam My biology text book and my professor (who has a phd, btw) disagree with you. take down this post. seriously, learn to correct yourself when you're wrong. you can screw up learning this for someone else.

[SouhaaMusic]

Thank you :)

[cbro63]

Actually I think you have this wrong Sal. From the germ cell with ploidy of 2n, at the end of Telophase I you identify 2 daughter cells with ploidy of n each. Then at the end of Telophase II you identify four daughter cells with ploidy of n each. Isn't the ploidy of the cells at the end of Telophase 1 2n?

[riojangeli]

@cbro63 no. it is in meiosis 1 where the chromosome count was halved. so at the end of meiosis 1, specifically telophase 1, the 2 daughter cells have ploidy of "n" each. moreover, meiosis 2 is quite the same with mitosis, and so ploidy of "n" was retained till the end of telophase 2