MEIOSIS A-Level Biology - How CROSSING OVER and INDEPENDENT SEGREGATION introduce genetic variation
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- čas přidán 27. 07. 2024
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your videos are so useful! i wish there was someone like you to cover my other alevel subjects haha
Thank you! I'm so glad they are helping you
Your vidoes have been helping me a lot through my IALs. Thank you!!! x
I'm so glad!
Just learning about this for the first time, extremely useful for making notes. Thank you!
You're welcome, glad it was helpful to make notes!
Your videos are the best I have found so far!!
Wow, thanks! So pleased you like them :)
Never understood meiosis since secondary school, learning it for the exams tomorrow
Wow this is so helpful, I finally understand! thank you so much!
Ah yes, that's great to hear Elli. Really pleased you found it helpful and it helped you to understand this topic 😀
Wonderful video, much appreciated
Glad it was helpful!
A huge thank you miss Estruch ,YOU RESOLVE MY CONFUSION
I'm so pleased 😀
This is such a great vid!
Thank you, glad it helped you. :D
Thank you so much! You are saving my as grades :)))
So pleased the videos are helping you 😊😊
thank u some much for this saved my life
Glad to have helped! Good luck with your studies 😀
got to understand meiosis better ,thanks
You're welcome, glad it helped you :D
You’re the best ever
☺ Thank you so much.
Hi miss do we have to know about bivalents and recombinants because that is what our teacher taught us and we also do aqa bio
well in lad great video
Thank you 😊
Mam your videos are so helpful in the examination, Also you are so beautiful 😍
So pleased they are helping 😀
Is the topic apart of the cell cycle and mitosis ?? For as biology
i dont get the paternal and maternal chromosomes on how are they present in meiosis one when after meiosis the sperm and egg will fertilise introducing the male and female genes
Does independent assortment and independent segregation same?
for aqa a level biology do you need to know the steps of meiosis, like prophase1, metaphase 1... etc ?
Hello, nope. For meiosis you just need to know the properties and how crossing over and independent segregation introduce variation
I completely understand Mitosis and Cycins at checkpoints and Phosporylation of protiens- all the stuff in Mitosis. But oh boy did Meiosis confuse me.
I hope this video helped with that 😊
@@MissEstruchBiology Yes, it did thanks! I hope you feel great because your helping lots of people learn!
LIFESAAAAVER! doing 2 a levels in one year and missed out a lot of info already. You rescue me!
you're so welcome! Good luck
2 à levels in one year?
@@idk-uv9dk yep. doing 4 in total wml
@@yaeltam damn, how is it like, how come you were allowed to do that
@@idk-uv9dk im clever and i asked and they said sure. worst decision of my life bro
So out of independent segregation and genetic recombination, which actually occurs first? And cos recombination only happens sometimes (Im assuming independent segregation always happens), in what cases does it happen like what causes recombination, is it random?
they'll be happening at very similar times as independent segregation involves the chromosomes aligning and crossing over happens when they are aligned.
Independent segregation always occurs and crossing over is random 😊
@@MissEstruchBiology ah makes sense. thank you so much ☺️
Do we need to know the process of meiosis 1 and 2 in detail?
Hello,
No you don't. For Meiosis you just need to know how variation is introduced.
The details of what happens at each stage is covered in mitosis in topic 2.
I am doing a project on meiosis and im suppose to draw a model of what it would look like with low genetic diversity.Would the model look similar to the model for mitosis?Im so confused i hope you can respond!
Hello,
Do you mean what meiosis would look like with low diversity?
I'm not exactly sure what is needed from those instructions, but low genetic diversity would mean there are not many alleles in the population, so maybe you need to show this on the chromosomes in your meiosis diagram.
what if chromatids break twice will it go back to normal
Hiya thank you for a good video. For AQA Alevel biology, is it required to know each stage of Meiosis I and Meiosis II.
So: Prophase I, Metaphase I, Anaphase I and Telophase I in meiosis I
and the same in Meiosis II etc.
Thank you :)
Hello,
No you don't for meiosis, but you do need this for mitosis.
Hope that helps ☺
so what exactly are the diploid cells that divide by meiosis to create gametes called? are they any ordinary body cell?
they are called germ cells (found in ovaries and testes in humans)
Which cell undergoes meiosis to create the gametes? They can't be body cells, right?
Exactly, meiosis happens in the testes and ovaries as this is where the gametes are formed.
hi I wanted to ask how comes in meiosis 1 It docent produce a diploid cell even though both gametes have half the number of chromosomes compared to the original cell?
In meiosis I, the homogous pairs of chromosomes are separated. A diploid cells has 2 copies of each chromosome (meaning homologous pairs). So this means it isn't a diploid cell. It is a haploid cell, but the chromatids haven't been separated yet.
Hope that helps
I’m guessing this isn’t for OCR A level Biology? We have to learn the different stages and what happens within each stage? Thanks anyway, the variation part was helpful 😊
Ah afraid not , its AQA
the variation bit is still applicable to ocr
Hi, so is crossing over in prophase 1 and then independent segregation in metaphase 1 for aqa alevel biology spec?
Hello,
For AQA you just say it's occurring in meiosis I, you don't state which phase.
Hope that helps ☺
Thank you
10:55 Hi Miss, why is it (2n)^2 possible combinations of chromosomes when you consider random fertilisation? Why is it squared and not any other number because it's random?
Thank you so much for the videos as well, they have been really helpful with revision 😊
That square doubles it instead of actually squaring it due to weird mathematics stuff
Hi Miss do we not need to know about the steps of meiosis in depth like we did for mitosis?
no not for AQA
@@MissEstruchBiology okay thank you. Also when you said that further variation can occur if fertilisation of gametes occur. Is that fertilisation of the haploid cells that were made in meiosis?
Does anyone know if there's mitosis video???
Yes there is
Doesn't crossing over occur at Prophase 1 and not metaphase 1?
you only have to know it occurs in meiosis I for A level. It starts to occur in prophase but it is still happening in metaphase, as this is when homologous pairs are lined up next to each other making crossing over possible.
Hope that helps
tysm for this video I have a question, after meoisis one are the cells haploid or diploid as some places i see it says diploid and others say haploid, which one would be relevant for the spec? many thanks!
The cells that enter meiosis II are haploid. They have one chromosome from each homologue pair, its just the chromosomes still have two sister chromatids. These sister chromatids separate in meiosis II, and the resulting cells ( the gametes) are still haploid cells, just not with the duplicated sister chromatid.
Hope that helps 😊
what do you mean by one set and two sets of chromosomes
0 dislikes, lets keep it that way
Aww thanks!!!
im assuming this video covers all exam boards or am i mistaken?
Hello :D
I haven't checked the level of detail against all exam boards. This is specifically for AQA but there will be lots of overlaps. I'd suggest checking against your spec though to be sure :D
3:44
What’s the difference between segregation and assortment
Like can you explain it?
images.app.goo.gl/JnPFoe8R2mfEUW6z7. This image is a really good summary that should help
for the diagram you used to show independent segregation would the possible number of combinations of chromosomes in daughter cells be 4 as 2^2 is 4? , thankyou
hello,
Yes thats right, there are 4 possible combinations for the example I gave 😊
@@MissEstruchBiology thankyou your videos help a lot :)
what happens during meiosis 2?
Hello,
Prophase II, metaphase II, anaphase Ii and telophase II ,much like they occur in mitosis.
@@MissEstruchBiology ohh ok thank you very much! your videos are helping me get through bio
So glad they are helping you 😁☺
2:45 that’s what I don’t get
Wdym exactly the same genes ?
So there’s a set amount of genes on the entire planet ?
hello,
By exactly the same genes I mean, for example, chromosome 9 is where the gene for blood group is located, so both copies of chromosome 9(homologous pairs) will have that same gene for blood group. They might be different versions (alleles) of the gene though.
Hope that helps.
@@MissEstruchBiology thanks
you're welcome 😊
I’m an identical twin
This topic is quite difficult…would have liked some definitions of the vocabulary used. I needed a clear concise explanation of the word “homologous “ and “ allele”….and I found the diagram showing independent segregation really difficult to understand. There’s no key as to the annotations used or verbal explanation and I couldn’t clearly see how the diagram is depicting the separation of the chromatids …also the diagram and explanation identifying meiosis in a life cycle was difficult to grasp .. maybe because of so much detail in the diagram ? totally confused !!! 😢
shes got another video explaining the terminology in her Y12 Biology playlist, watch that one first before you watch this one
the independent segregation diagram is not actually that necessary, if you know the stages of mitosis (prophase,anaphase etc) you should also know the stages of meiosis, theyre the same, they just occurs twice (meiosis I and meiosis II)
At 4:56 wouldn't n be 22 since humans have 22 pairs of homologous chromosomes( the 23rd pair is the sex chromosome)
Hello,
Yes if the individual is biologically a male as they would have 23 pairs of chromosomes of which 22 are homologous. Females do have 23 homologous pairs of chromosomes though, as their sex chromosomes are both X chromosome.
have bio paper 1 in 4 hours lmao
Good luck!
How did it go?
@@MissEstruchBiology thank you!!
@@bobguy4727 it went better than expected but I forgot to learn basic definitions:///// its a reminder for next time for sure haha
@@hs-dc6il Oh yeah it's so annoying cause like u know what it means but just not the exact words the marks scheme wants. Gl for paper 2!
great video but remember there is a difference between Independent Assortment and Independent segregation.
What you are describing is not segregation but assortment.
hey thanks for highlighting. This is for AQA, and for this exam board, the mark is for saying segregation. I do appreciate though that this may not be as specific as it should, but that's the what the spec says 🤷🏻♀️
Thank youu very muchhh!!!!
Your videos in bio are always the ones that help me pass 🥹
aww I'm so pleased ☺️