Chromosomal Abnormalities, Aneuploidy and Non-Disjunction

NOTE! The label for "sister chromatids" at 1:30 should say "homologous chromosomes"! Sadly, KZbin deleted the "annotations" feature that had previously corrected the error. Thanks for the viewers who noticed the problem!
Chromosomal problems can easily occur during reproduction. Continuing our discussion of reproduction, this screencast concerns common chromosomal abnormalities, specifically non-disjunction. During nondisjunction, an incorrect number of chromosomes are allocated into the resulting sex cells.

[@ARCHER-ch4xn]

I learned more things here than the 3 months lecture in school Thankyou! you saved my semester

[@BOGObiology]

Shucks! Thanks so much, Markus! This made my day! Do you have suggestions for other videos that would be helpful?

[@britoronto6628]

Oh dear. Your semester is still in trouble I"m afraid. This video contains incorrect information--I suggest you crack a book rather than rely on youtube!

[@bananamanjunior7575]

God damn tards

[@sylvialarsson9790]

Besides the one terminology hiccup at 1:30, which I see you have already made attempts to rectify. This is a wonderful video, clear, concise, and informative. Your students are very lucky!

[@BOGObiology]

Thanks Sylvia! And yes, it's a huge, huge pain that you can't change video content once it's up. Someday I'll get around to re-doing this video. Sending love from Boston! -BOGO

[@DavidNasr]

This video is absolutely AWESOME! I've been struggling with these as I lack a foundation in Biology for having slacked off in my earlier school years, this helped clear all my uncertainties. Thank you so much!

[@Keletsonx]

This is way better than trying to make sense of confusing notes on a textbook thank you 🙏

[@smashez08]

My partner has pericentric inversion of chromosome 9, p11q13. What does that mean for having children in future? Are we at a higher risks for having children with health problems?!

[@milenachaufan5930]

XY determine the chromosomal sex, not the gender, that’s a social concept. Plus genital sex could be different than chromosomal or different than hormonal sex. We teach this at university of Buenos Aires medicine school and it should be taught in every university

[@BOGObiology]

Hi Milena, yes, you are right and I agree with you. However, I made this video for my teenage students and every time they heard the word "sex" they would go into fits of giggles and would be off topic for the rest of class. So, I swapped in "gender" when I made the video just so we could get through the video as a group. We discussed sex, gender and sexual reproduction at great length in another unit, once they were a little more comfortable with biology and with anatomy and had matured a little bit. Win some, lose some. Love, BOGO

[@ali3ghouse292]

Came here for clarity on non-disjunction - clear video, well paced with clear info. Thanks!

[@BOGObiology]

Thanks, Ali! Glad to hear it was useful! One of these days I'll get around to making a "cleaner" version with better handwriting! Sending you best wishes from Boston! -BOGO

[@tayyabashahid9601]

This is the best explanation of non disjunction I've had! Thanks a bunch!

[@britoronto6628]

WARNING--incorrect information in this video! At T=2', the chromosomes depicted are NOT sister chromatids, they are homologous chromosomes (ie one you got from mom and one from dad). Sister chromatids result from DNA replication and thus in G2/M phase, each homolog will be made up of two identical sister chromatids that are paired together. Homologous chromosomes however differ from each other, and will contain different versions of each gene (ie alleles).

[@BOGObiology]

Thanks for catching that; KZbin deleted the annotations feature, which had previously mentioned the error and corrected it. I'll put a note in the description and try to rig up something using the "cards" feature!

[@anupama1519]

Your explanation is very very helpful and visuals are very clear and perfect. Thank you so much for this concised video❤️❤️ Love from India 🇮🇳🇮🇳

[@BOGObiology]

Thanks, Anupama! Sending love and best wishes back from Boston! -BOGO

[@medishine044]

Nondisjunction in meiosis I occurs when the tetrads fail to separate during anaphase I. At the end of meiosis I, there will be 2 haploid daughter cells, one with n+1 and the other with n-1. Both of these daughter cells will then go on to divide once more in meiosis II, producing 4 daughter cells, 2 with n+1 and 2 with n-1. -journal why in this video nondisjunction in meiosis I causes trisomy (2n+1) and monosomy (2n-1)?

[@opufy]

think of it this way, the early the problem occurs the bigger the issue becomes. nondisjunction at meiosis I means meiosis II will make things worse, at meiosis II being the only site of nondisjunction, it is less severe.

[@Selen_light]

Oh well thats really thankful..✨️

[@laurengao5821]

I like this lecture a lot! Thanks for making this awesome video. However, I think at 1:43 the chromosomes should not be referred to as sister chromatids as the term chromatids should only be used with replicated chromosomes connected at the centromere.

[@BOGObiology]

Hi Lauren, thanks for the comment! Yes, there used to be an option to put a little "sticker" on the video that corrected the mis-speak, but youtube has since removed the option to do that (ugh). I put a note in the video description but unfortunately once it's up you're not allowed to add anything or re-record. I've tried! Stay safe out there! -BOGO

[@alexandramaclachlan7597]

Brilliant video, and cheers for the clarification re: the 'sister chromatids' hiccup. Gotta be that guy though, and remind people of the distinction b/w gender (social) and sex (biological) ;)

[@uncxmfy]

thank you :) it really bothered me the way she kept using harmful and incorrect terminology with gender and sex

[@Tnbeazy]

Thank you for this explanation! Very informative. Do you know if one can call the chromatids at the end of meioses (II) chromosomes as well? I think I picked that up somewhere.

[@montyzarr1866]

Each pair are made from 2 homologous chromosomes not sister chromatids. Sister chromatids are introduce during s-phase of interphase when DNA is replicated.

[@user-ty4zq5zn8x]

agree

[@user-nt8vu2nz5h]

EXACTLY!! she’s confusing people and she still hasn’t deleted the video or said anything about the mistake .. I saw the mistake 1:53 and I literally had to rethink everything that I’ve learned cuz I thought I was wrong ..

[@cajesnoli5493]

What cytological abnormalities are expected of aneuploids at mitosis? At meiosis?

[@nooonii2248]

Thank you for this demonstration. I think karyotyping show homologous chromosomes and not sister chromatids?

[@spicydiarrhea5662]

if it's ethical topic people should also care about cancelling the processes of apoptosis and other biological mechanisms that eliminates defective offspring with chromosomal abnormalities / aberrations.

[@hemantupadhayay954]

That's the homologus chromosome Sister chromatids are from same chromosome which have replicated it's dna

[@alyssafox565]

I had a miscarriage due to Chromosomal Abnormalities but the Dr couldn’t find or detect which chromosomal abnormalities it was i was I was just told the babies heart stopped developing at 3 months and miscarried at 16 weeks is this considered a spontaneous miscarriage or what ?

[@BOGObiology]

Hi Alyssa, first off I'm so sorry for your loss. This must have been a very difficult time for you and I hope you have a strong support network of people who care about you. Please note that I'm not an MD, but based on my understanding of the term, yes this would be considered a spontaneous miscarriage. Generally speaking, the early rounds of cell division need to go absolutely perfectly, and in at least 1 in 4 pregnancies they don't quite get it right. The cells also need to communicate with one another in precisely the right way in order to begin growing into exactly the right tissues in exactly the right places. The hormones and growth factors and cell signaling compounds all need to be created and maintained and adjusted at just the right times, and more. It's like a developmental symphony; all the instruments must join in and drop out at the right times, play the correct notes, loudly or softly, fast or slow in order to create a complex and harmonious piece of music. A single instrument out of tune or out of sync can be very disruptive. If just a couple early rounds of cell division don't quite go the way they should, all of those cells' descendants will likely also have an abnormal number of chromosomes. These cells will all be missing a piece of their genetic code that contains important instructions for how to do their job, or they may have equally confusing duplicate sets of instructions. Not all abnormalities are fatal, but for many I'm afraid it's only a matter of time before the cells with missing or duplicate DNA will need to perform essential developmental tasks and they won't be up to it. I hope this helps to explain. Sending you tons of love and support. Love, BOGO

[@alyssafox565]

@@BOGObiology thank you so much I just didn’t understand why the Dr.s couldn’t explain why I miscarries like I said they told me abnormalities were detected but can’t determine exactly which ones and also the lady that did my ultrasound couldn’t find a heartbeat and said her gestational heart size was the size of an embryo of 3 months

[@alyssafox565]

@@BOGObiology and I also remember having a clot come out into the toilet around 3 months it’s was approximately the size of 2 or 3 quarters it was a brownish tan color with red discharge around it could that be possibly when the miscarriage started ?

[@evamandri]

Wow! Is that what happens with high and low mosaic embryos when talking about abnormal MI and MII?

[@aliyuyusuf9443]

I study Human Anatomy it's a type of course that need a lot of cramming and drawing but I am a type of person not good in cramming this videos simplify the whole stuffs release my tension

[@BOGObiology]

Thanks, Aliyu! I'm so happy it was helpful! Sending you best wishes from Boston! -BOGO

[@lennardschmidt4358]

Isn't the distribution of red and blue chromatids random in the end of meiosis 2? Because the allignement in the both prophase is random. Plus you would get mixed red and blue chromatids, because of the crossing over during Synapsis, wouldn't you?

[@BOGObiology]

You are right, and I originally drew it that way. HOWEVER, my students then couldn't tell the difference between the chromatids because they all looked basically the same. So, when I re-made the video I showed a simplified version and made a second video that showed independent assortment and crossing over. Hope this clarifies!

[@user-jc1yl6uf4x]

Thanks a lot 💓 I'm not a English speaker but i understand what you said

[@gregoryhudak802]

Insert "homologous chromosomes" @ 1:35 in place of "sister chromatids" Otherwise well done. Thank you for posting.

[@tahamahmudov9375]

thanks for the excellent explanation

[@cocekamhlawuli9726]

Incorrect information; the 23pairs INCLUDE sex chromosomes ie 22 pairs = Autosomal chromosomes and 23rd last pair is sex chromosomes.

[@skoufoss]

The homologus chromosomes are in synapsis during prophase I. You depict a synapsis among non-homologus.

[@panteasardari5657]

Amazing explanation 🙏🏻

[@BOGObiology]

Glad you think so! Sending love and best wishes from Boston MA!

[@funny11744]

A question :related karyotype abnormalities in the cell : I read about a trial with stem cell where a small number of patients were excluded because of that. QUESTION: These karyotype abnormalities in the cell - are related in this case only for genetic disease discovered from birth or is about all genetic disease? Please detail answer. Thanks.

[@nynmlg2299]

Thank you greetings from Germany

[@BOGObiology]

Thank you too!

[@cayanlamanna]

diploid actually means that each set of chromosomes is composed of 2 chromosomes

[@javi9059]

Beautiful explanation!!! Thank you so much!

[@a.h.s5152]

So an XX 46 is a normal female ?

[@ivaniam681]

Information is wrong at 2:00. The chromosomes with arrows are homologous chromosomes. Not sister chromatids

[@BOGObiology]

Yes, it's mentioned in the video description. Unfortunately, youtube deleted the little blurb that used to pop up pointing it out! -BOGO

[@0fryguy0]

i could be wrong but i think meiosis starts with a diploid cell that duplicates each chromosome before splitting (ie. tetraploid). if thats the case, then it should probably be labeled in the diagrams at 4:49

[@BOGObiology]

Great feedback; in retrospect, it's poorly labeled. The diagram is supposed to show what things look like at the END of meiosis I and meiosis II, but that's not super clear because I never explicitly said so. I made this in between classes back when I was teaching full time, if I were to re-do this video, I'd definitely label it differently and would also include ongoing labels showing the ploidy at every step. I'd also definitely draw more neatly... Hindsight is 20/20! Sending love and best wishes from Boston! -BOGO

[@manbeefcake]

The video header says aneuploidy, but no mention in the video. The word wasn't even used in the video.

[@BOGObiology]

Sorry, you're right. I originally made this for my students and they had to write their own definition of aneuploidy using a series of examples. It's just a word that means "having a different number of chromosomes than what would be expected"

[@blessingutomi5622]

I totally love your video but i have a question about an assignment. The question is 'what's the difference between aneuploidy abnormalities and non-aneuploidy abnormalities'. But the issue now is that i've not seen anything like 'non-aneuploidy abnormalities' on the net. i've only seen 'aneuploidy abnormalities'. Please i urgrntly need assistance. Thank you.

[@BOGObiology]

Hi Blessing! "Aneuploidy" just means "when the number of chromosomes is wrong", either too many or too few. I'm assuming that "non-aneuploidy" abnormalities would be "things that can go wrong besides having the wrong number of chromosomes". A LOT can actually go wrong with cell division even if the correct number of chromosomes end up in each cell. UV rays, x rays, certain toxins (e.g. chromium in groundwater) and a lot of other things can really goof up the DNA that's rolled up to make the chromosomes. UV rays, for instance, cause the "Ts" in DNA to clump together weirdly, instead of pairing with As. This means they won't make the correct proteins and won't be copied correctly. Perhaps that sort of thing is what the question is looking for? Love, BOGO

[@blessingutomi5622]

@@BOGObiology Thank you for your reply, i didn't think about that at all. And yes, now that you mentioned it, i think that's what my lecturer meant when she gave the assignment. I'll be sure to do more research on it.

[@blessingutomi5622]

@@BOGObiology Thank you. I totally understand it better.

[@grunktabulous]

Omg u saved my life, tysm

[@snpxpain2627]

Thats saved 2 hours of studying paediatrics

[@ngagshsh5749]

You didn’t differentiate between chromosomes and chromatid and father and mother

[@bonodipchowdhury6591]

What kind of aneuploid gametes will be formed if non-disjunction occurs at meiosis-1? Is it both n+1 and n-1 ?

[@apkapokemonunitegamer1242]

Idiot

[@medishine044]

yea i read that too in journal

[@khoa893]

1:41 shows wrong information, that two chromatids of the chromosome 5 is homologous chromosomes, not sister chromosome :((

[@BOGObiology]

Argh, it's so frustrating that I can't have a little sticker on the video anymore! (And that youtube won't let you edit the voiceover after you post the video!)

[@khoa893]

@@BOGObiology its okay, these terms are sometimes similar

[@silkecarina991]

this is great.

[@BOGObiology]

Thanks, Silke!

[@Supergirl-sd9th]

I've put the thousandth like hahaha, u're amazing thank u

[@BOGObiology]

Thanks for saying hi, Nour! Sending love and best wishes from Boston! -BOGO

[@ryanfrancis2640]

excellent vid to refresh the memory thanks

[@krusherchris6233]

your drawing of meiosis is wrong. parental chromosomes segregate to different cells separately.

[@user-pv5qq4um4s]

I think there is wrong in this video .

[@Ahmed-cn1vo]

I need reference for mechanim of abnormal kayotype,,please

[@mikerichards8456]

damn bluntly put but facts

[@lindaabah9826]

Superb

[@crimmc561]

Thank u ❤️

[@ChrisandTyCox]

What's the odds of having a healthy baby after miscarriage due to trisomy 8?

[@BOGObiology]

Wish I could tell you; that's something to discuss with a doctor who specializes in fertility. Lots of love and best of luck! -BOGO

[@OwOchina]

3:13 yes

[@lanolas8362]

thanks alot

[@erikasoriano1918]

So clear thank you so much 😊

[@BOGObiology]

Thanks, Erika! Sending best wishes from Boston! -BOGO

[@re1ence633]

Thank You so much

[@BOGObiology]

You're so welcome, LogixSai! Sending best wishes from Boston! -BOGO

[@fapjack1836]

1:33 a pair of homologous chromosomes

[@PriyaKarthik-vu8wn]

Trisomy 21, 18, 13 low meaning plz and then down syndrome negative meaning plz give me the details

[@-yayschmitty-8440]

But ma'am, I'm unable to attend class due to unfortunate circumstances. And also, my dog ate the questions that I have written in relation to the topic. Please excuse me ma'am.

[@apkapokemonunitegamer1242]

So what

[@apkapokemonunitegamer1242]

You unable to attend the classe

[@apkapokemonunitegamer1242]

And this is not a online classes

[@apkapokemonunitegamer1242]

Understand

[@apkapokemonunitegamer1242]

Stupid

[@kooisoooi5187]

3:54 why are there 4 chromosomes, i thought there should be only 2 ????????

[@BOGObiology]

It's totally annoying; this is a vocabulary issue. We use the same word "chromosomes" to describe both the PAIRS of genetic material bundles (second row) as well as the separated individual bundles of genetic material (third row). I really wish there was a different word because it always confuses people. Annoying, annoying, annoying! -BOGO

[@KingNat.]

Amazing, well done

[@BOGObiology]

Thanks, KingNat! I've never been congratulated by royalty before ; ) Sending you best wishes from Boston! -BOGO

[@apkapokemonunitegamer1242]

Befcufe

[@apotheosistheurbanmonk2341]

That was an amazing break down

[@BOGObiology]

Thanks, Apotheosis! Stay safe out there! Love, BOGO

[@bavitra2183]

why is there 2 red and 2 blue to start off with shouldnt it be 1 red and 1 blue im confused

[@BOGObiology]

Hi Ivab. Remember that this is MEIOSIS, not mitosis. The "n" gets split in half during meiosis, unlike in mitosis where you just duplicate all the chromosomes. I drew 4 chromosomes (2 pairs) to illustrate the concept so it could easily be seen, but in reality there would be 46 chromosomes arranged into 23 pairs, but that would have been a complete pain to draw. Love BOGO

[@vetalablossom]

can a non-disjunction occur in the mitosis?

[@maritw6854]

Yes it can. When a whole chromosome (not just one chromatid like normally) is pulled to one side during anafase. So you end up with 45 chromosomes in one cell and 47 chromosomes in the other.

[@maritw6854]

You can compare it to what happens with non-disjunction in myosis II

[@zainab_abd3776]

مرحبا ممكن أعرف اذا كنت بدرس دروس خصوصية لمواد المجموعة الطبية ؟؟ يا ريت تساعدوني

[@BOGObiology]

مرحبا! لقد صنعت هذا الفيديو لطلاب البيولوجيا ، لكن يمكن لأي شخص مشاهدته. وآمل أن يكون مفيدا! أطيب الأماني!

[@zainab_abd3776]

@@BOGObiology هل تجيد اللغة العربية ؟

[@BOGObiology]

@@zainab_abd3776 لسوء الحظ ، لا أستطيع التحدث باللغة العربية. أنا فقط أتحدث الإنجليزية والفرنسية والإسبانية قليلاً. انا استخدم مترجم جوجل!

[@sasom7274]

I think the thumbnail photo is incorrect. It's not the same as 6:56.

[@BOGObiology]

Hi, I wasn't happy with the original thumbnail taken from the video, so I made all the drawings bigger and in brighter colors and changed up the arrangement slightly so it'd be easier to see when it was small. The overall meaning should be the same though! Love, BOGO

[@sasom7274]

@@BOGObiology Hi. I think the thumbnail is incorrect. The middle part does not represent M1 non disjunction

[@BOGObiology]

@@sasom7274 Holy cow, you're right! I just downloaded a bigger version of the thumbnail, and you're totally correct! I somehow switched the M1 and M2 nondisjunction labels! Once I'm done working, I'll fix it and re-upload. 50 cool points to you and thank you!!!

[@sasom7274]

@@BOGObiology Thank you for the cool points. Make sure to delete the photo off google search as well with search engine. I almost learned wrong. But thank you for the video. You’re awesome.

[@helen.3221]

That problem jast in 21 ?

[@jswag2005]

It’s her child she made it she should be able to decide if she wants it or not

[@b4byheart726]

Yeah she can give them up for adoption if she doesn’t want them.

[@subhanwahab1191]

22xx normal chromosome plz tell me

[@BOGObiology]

Hi Subhan, I actually don't understand what you're asking. Can you please rewrite your comment as a question? -BOGO

[@subhanwahab1191]

My sister chromosome total number is 22xx plz tell me 22xx normal chromosome or abnormal doctor says abnormal chromosome her body

[@BOGObiology]

@@subhanwahab1191 Most people have 22 pairs of chromosomes plus a 23rd pair of either X and X or X and Y sex chromosomes. It's much more common to have extra chromosomes than to be missing chromosomes. Missing a chromosome is known as monosomy. However, I'm not an expert on this topic, so if you have questions about your sister's health, you should definitely speak to your doctor. Sending love to you and your family from Boston! -BOGO

[@Endoe.McKronic]

7:42 See you in class? You mean I have to go to your CLASS NOW!!??

[@BOGObiology]

HA! Well, I made this originally for my actual students...

[@Rob-ou4vk]

thank you po

[@BOGObiology]

You're welcome! Glad it was helpful

[@mvelobonga7968]

Thank you so much this helps

[@BOGObiology]

Glad it helped, Mvelo! Sending love from Boston!

[@chiahsuantsauo8375]

nice 8min spent

[@stumizathemiza9577]

Thanks alot ...can wait for human reproduction 🙆‍♂️🔥🔥🔥✌😌

[@lamboastonmartin8092]

2:01 lgbtq TRIGGERD

[@BOGObiology]

Hi Kyle, thanks for bringing this up; it merits a conversation. I made this video back in 2013 and uploaded the file in 2015. At the time, discussions of sex (chromosomal and physiological characteristics) vs gender (how someone identifies, behaves, etc.) weren't nearly as mainstream as they are today. There's also a whole other facet involving someone who is intersex (having physiological characteristics that don't conform to being entirely male or female). While those topics and discussions are very interesting, they were outside the scope of this video and thus aren't discussed. If you're interested in this topic, I recommend the book "Sexing the Body" by Dr. Fausto-Sterling. Also, just for the record, "triggered" has two "e's". Effective trolling requires good grammar. -BOGO

[@bananamanjunior7575]

@@BOGObiology 2:02 "notice that the Y chromosome is short and stubby". why you hatin on the Y chromosomes it's not their fault they born short :(

[@davidmoya6449]

*biological sex, not gender

[@BOGObiology]

Yes, I know, thank you. I recorded this live and now I can’t change it. I used to have a little decal that popped up with a correction but KZbin no longer allows that feature.