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Updated Mar 24, 2026
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Proces mejoze in tvorba spolnih celic
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Mejoza in nastanek spolnih celic
Predstavljaj si mejozo kot posebno "tovorno celično delitev", ki razpolovi število kromosomov. Iz ene diploidne celice (2n), ki ima dva kompleta kromosomov, nastanejo štiri haploidne celice (n) z enim kompletom kromosomov. Te postanejo spolne celice ali gamete.
Namen mejoze je dvojen: prvič, zmanjša število kromosomov na polovico, da se pri oploditvi spet vzpostavi normalno število. Drugič, ustvari genetsko raznolikost med potomci z mešanjem genskega materiala.
Diploidne celice (2n) imajo dva seta kromosomov - pri človeku 46. To so vse tvoje telesne celice. Haploidne celice (n) pa imajo samo en set - pri človeku 23. To so spermiji in jajčeca.
Homologna kromosoma sta kot par podobnih čevljev - enako velika, s centromerom na istem mestu, nosita pa gene za iste lastnosti. Crossing-over je izmenjava delov DNA med kromosomoma in je ključen za genetsko raznolikost.
💡 Nasvet: Zapomni si razliko med diploidno in haploidno celico - to je osnova za razumevanje mejoze!
Mejoza I - Redukcijska delitev
Mejoza I je prva in bolj zapletena delitev, kjer se homologni kromosomi ločijo. Tu se število kromosomov razpolovi (2n → n).
V profazi I se zgodijo najpomembnejše stvari. Kromosomi se zgostijo, homologni pari se združijo v bivalente, nato pa se zgodi crossing-over. To je izmenjava genetskega materiala med kromosomoma, ki ustvari nove kombinacije genov.
Metafaza I je ključna za genetsko raznolikost. Bivalenti se postavijo v sredino celice, vendar se vsak par naključno orientira proti poloma. To neodvisno razvrščanje pomeni, da lahko dobiš milijone različnih kombinacij.
V anafazi I se zgodi nekaj posebnega - homologni kromosomi se ločijo, vendar sestrski kromatidi ostanejo skupaj! To je glavna razlika od mitoze. V telofazi I se celica razdeli na dve haploidni celici.
💡 Pomembno: V anafazi I se ločujejo homologni kromosomi, ne sestrski kromatidi - to zapomni za test!
Mejoza II - Ekvacijska delitev
Mejoza II je precej podobna mitozi in jo imenujemo ekvacijska delitev. Tu se končno ločijo sestrski kromatidi.
V profazi II se kromosomi v obeh haploidnih celicah ponovno pripravijo na delitev. Oblikuje se novo delitveno vreteno.
Metafaza II je preprosta - kromosomi se poravnajo v sredini celice. Vsak kromosom je še vedno sestavljen iz dveh sestrskih kromatid.
Anafaza II je odločilna - centromeri se razdelijo in sestrski kromatidi se končno ločijo! Sedaj potujejo proti nasprotnim polom kot samostojni kromosomi.
V telofazi II se obe celici razdelita. Končni rezultat: iz ene diploidne celice so nastale štiri haploidne celice, ki so vse genetsko edinstvene!
💡 Zapomnij si: Mejoza II je kot mitoza, samo da se zgodi v haploidnih celicah!
Primerjava mitoze in mejoze
Razlike med mitozo in mejozo so ključne za razumevanje. Mitoza služi rasti in obnovi, mejoza pa nastanku spolnih celic.
Mitoza ima eno delitev in ustvari dve identični diploidni celici. Mejoza ima dve delitvi in ustvari štiri različne haploidne celice. Pri mitozi se crossing-over ne zgodi, pri mejozi pa je ključen za genetsko raznolikost.
Glavna razlika v anafazi: pri mitozi se ločijo sestrski kromatidi, pri mejozi I pa homologni kromosomi. Šele v mejozi II se ločijo sestrski kromatidi.
Genetska variabilnost nastane zaradi dveh procesov: crossing-over v profazi I (rekombinacija genov) in neodvisno razvrščanje homolognih kromosomov v metafazi I.
Če se kaj zalomi pri mejozi (nerazdvajanje kromosomov), lahko nastanejo gamete z napačnim številom kromosomov. To vodi do genetskih motenj, kot je Downov sindrom.
💡 Za test: Ključna razlika je v anafazi I - ločujejo se homologni kromosomi, ne sestrski kromatidi!
Spermatogeneza vs. oogeneza
Pri moških in ženskah se mejoza izvaja malo drugače, čeprav je osnovni proces enak.
Pri spermatogenezi (tvorba spermija) iz ene celice nastanejo štirje funkcionalni spermiji. Vsi štirje so približno enako veliki in vsi lahko oplodijo jajčno celico.
Pri oogenezi (tvorba jajčnih celic) pa iz ene celice nastane le ena velika funkcionalna jajčna celica in tri majhna polarna telesca, ki propadejo. Jajčna celica dobi skoraj vso citoplazmo, ker potrebuje zaloge hranil za razvoj zarodka.
Ta razlika je smiselna - spermiji morajo biti majhni in gibljivi za plavanje, jajčna celica pa velika z zalogami za hranjenje zarodka po oploditvi.
Napake pri mejozi lahko vodijo do gamet z napačnim številom kromosomov. Ko se takšna gameta oplodi, lahko nastanejo genetske motnje, kot je trisomija 21.
💡 Zanimivost: Ženska se rodi z vsemi jajčnimi celicami, ki jih bo imela v življenju - te celice lahko čakajo desetletja, da dokončajo mejozo!
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Is Knowunity really free of charge?
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The app is very easy to use and well designed. I have found everything I was looking for so far and have been able to learn a lot from the presentations! I will definitely use the app for a class assignment! And of course it also helps a lot as an inspiration.
Stefan S
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This app is really great. There are so many study notes and help [...]. My problem subject is French, for example, and the app has so many options for help. Thanks to this app, I have improved my French. I would recommend it to anyone.
Samantha Klich
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Wow, I am really amazed. I just tried the app because I've seen it advertised many times and was absolutely stunned. This app is THE HELP you want for school and above all, it offers so many things, such as workouts and fact sheets, which have been VERY helpful to me personally.
Anna
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Best app on earth! no words because it’s too good
Thomas R
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Just amazing. Let's me revise 10x better, this app is a quick 10/10. I highly recommend it to anyone. I can watch and search for notes. I can save them in the subject folder. I can revise it any time when I come back. If you haven't tried this app, you're really missing out.
Basil
Android user
This app has made me feel so much more confident in my exam prep, not only through boosting my own self confidence through the features that allow you to connect with others and feel less alone, but also through the way the app itself is centred around making you feel better. It is easy to navigate, fun to use, and helpful to anyone struggling in absolutely any way.
David K
iOS user
The app's just great! All I have to do is enter the topic in the search bar and I get the response real fast. I don't have to watch 10 YouTube videos to understand something, so I'm saving my time. Highly recommended!
Sudenaz Ocak
Android user
In school I was really bad at maths but thanks to the app, I am doing better now. I am so grateful that you made the app.
Greenlight Bonnie
Android user
very reliable app to help and grow your ideas of Maths, English and other related topics in your works. please use this app if your struggling in areas, this app is key for that. wish I'd of done a review before. and it's also free so don't worry about that.
Rohan U
Android user
I know a lot of apps use fake accounts to boost their reviews but this app deserves it all. Originally I was getting 4 in my English exams and this time I got a grade 7. I didn’t even know about this app three days until the exam and it has helped A LOT. Please actually trust me and use it as I’m sure you too will see developments.
Xander S
iOS user
THE QUIZES AND FLASHCARDS ARE SO USEFUL AND I LOVE Knowunity AI. IT ALSO IS LITREALLY LIKE CHATGPT BUT SMARTER!! HELPED ME WITH MY MASCARA PROBLEMS TOO!! AS WELL AS MY REAL SUBJECTS ! DUHHH 😍😁😲🤑💗✨🎀😮
Elisha
iOS user
This apps acc the goat. I find revision so boring but this app makes it so easy to organize it all and then you can ask the freeeee ai to test yourself so good and you can easily upload your own stuff. highly recommend as someone taking mocks now
Paul T
iOS user
The app is very easy to use and well designed. I have found everything I was looking for so far and have been able to learn a lot from the presentations! I will definitely use the app for a class assignment! And of course it also helps a lot as an inspiration.
Stefan S
iOS user
This app is really great. There are so many study notes and help [...]. My problem subject is French, for example, and the app has so many options for help. Thanks to this app, I have improved my French. I would recommend it to anyone.
Samantha Klich
Android user
Wow, I am really amazed. I just tried the app because I've seen it advertised many times and was absolutely stunned. This app is THE HELP you want for school and above all, it offers so many things, such as workouts and fact sheets, which have been VERY helpful to me personally.
Anna
iOS user
Best app on earth! no words because it’s too good
Thomas R
iOS user
Just amazing. Let's me revise 10x better, this app is a quick 10/10. I highly recommend it to anyone. I can watch and search for notes. I can save them in the subject folder. I can revise it any time when I come back. If you haven't tried this app, you're really missing out.
Basil
Android user
This app has made me feel so much more confident in my exam prep, not only through boosting my own self confidence through the features that allow you to connect with others and feel less alone, but also through the way the app itself is centred around making you feel better. It is easy to navigate, fun to use, and helpful to anyone struggling in absolutely any way.
David K
iOS user
The app's just great! All I have to do is enter the topic in the search bar and I get the response real fast. I don't have to watch 10 YouTube videos to understand something, so I'm saving my time. Highly recommended!
Sudenaz Ocak
Android user
In school I was really bad at maths but thanks to the app, I am doing better now. I am so grateful that you made the app.
Greenlight Bonnie
Android user
very reliable app to help and grow your ideas of Maths, English and other related topics in your works. please use this app if your struggling in areas, this app is key for that. wish I'd of done a review before. and it's also free so don't worry about that.
Rohan U
Android user
I know a lot of apps use fake accounts to boost their reviews but this app deserves it all. Originally I was getting 4 in my English exams and this time I got a grade 7. I didn’t even know about this app three days until the exam and it has helped A LOT. Please actually trust me and use it as I’m sure you too will see developments.
Xander S
iOS user
THE QUIZES AND FLASHCARDS ARE SO USEFUL AND I LOVE Knowunity AI. IT ALSO IS LITREALLY LIKE CHATGPT BUT SMARTER!! HELPED ME WITH MY MASCARA PROBLEMS TOO!! AS WELL AS MY REAL SUBJECTS ! DUHHH 😍😁😲🤑💗✨🎀😮
Elisha
iOS user
This apps acc the goat. I find revision so boring but this app makes it so easy to organize it all and then you can ask the freeeee ai to test yourself so good and you can easily upload your own stuff. highly recommend as someone taking mocks now
Paul T
iOS user
Proces mejoze in tvorba spolnih celic
Mejoza je super pomemben proces, ki omogoča nastanek spolnih celic - brez nje ne bi bilo spolnega razmnoževanja! Ta celična delitev je malo bolj zapletena od mitoze, ker iz ene diploidne celice nastanejo kar štiri genetsko različne haploidne celice.
Mejoza in nastanek spolnih celic
Predstavljaj si mejozo kot posebno "tovorno celično delitev", ki razpolovi število kromosomov. Iz ene diploidne celice (2n), ki ima dva kompleta kromosomov, nastanejo štiri haploidne celice (n) z enim kompletom kromosomov. Te postanejo spolne celice ali gamete.
Namen mejoze je dvojen: prvič, zmanjša število kromosomov na polovico, da se pri oploditvi spet vzpostavi normalno število. Drugič, ustvari genetsko raznolikost med potomci z mešanjem genskega materiala.
Diploidne celice (2n) imajo dva seta kromosomov - pri človeku 46. To so vse tvoje telesne celice. Haploidne celice (n) pa imajo samo en set - pri človeku 23. To so spermiji in jajčeca.
Homologna kromosoma sta kot par podobnih čevljev - enako velika, s centromerom na istem mestu, nosita pa gene za iste lastnosti. Crossing-over je izmenjava delov DNA med kromosomoma in je ključen za genetsko raznolikost.
💡 Nasvet: Zapomni si razliko med diploidno in haploidno celico - to je osnova za razumevanje mejoze!
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Mejoza I - Redukcijska delitev
Mejoza I je prva in bolj zapletena delitev, kjer se homologni kromosomi ločijo. Tu se število kromosomov razpolovi (2n → n).
V profazi I se zgodijo najpomembnejše stvari. Kromosomi se zgostijo, homologni pari se združijo v bivalente, nato pa se zgodi crossing-over. To je izmenjava genetskega materiala med kromosomoma, ki ustvari nove kombinacije genov.
Metafaza I je ključna za genetsko raznolikost. Bivalenti se postavijo v sredino celice, vendar se vsak par naključno orientira proti poloma. To neodvisno razvrščanje pomeni, da lahko dobiš milijone različnih kombinacij.
V anafazi I se zgodi nekaj posebnega - homologni kromosomi se ločijo, vendar sestrski kromatidi ostanejo skupaj! To je glavna razlika od mitoze. V telofazi I se celica razdeli na dve haploidni celici.
💡 Pomembno: V anafazi I se ločujejo homologni kromosomi, ne sestrski kromatidi - to zapomni za test!
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Mejoza II - Ekvacijska delitev
Mejoza II je precej podobna mitozi in jo imenujemo ekvacijska delitev. Tu se končno ločijo sestrski kromatidi.
V profazi II se kromosomi v obeh haploidnih celicah ponovno pripravijo na delitev. Oblikuje se novo delitveno vreteno.
Metafaza II je preprosta - kromosomi se poravnajo v sredini celice. Vsak kromosom je še vedno sestavljen iz dveh sestrskih kromatid.
Anafaza II je odločilna - centromeri se razdelijo in sestrski kromatidi se končno ločijo! Sedaj potujejo proti nasprotnim polom kot samostojni kromosomi.
V telofazi II se obe celici razdelita. Končni rezultat: iz ene diploidne celice so nastale štiri haploidne celice, ki so vse genetsko edinstvene!
💡 Zapomnij si: Mejoza II je kot mitoza, samo da se zgodi v haploidnih celicah!
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Primerjava mitoze in mejoze
Razlike med mitozo in mejozo so ključne za razumevanje. Mitoza služi rasti in obnovi, mejoza pa nastanku spolnih celic.
Mitoza ima eno delitev in ustvari dve identični diploidni celici. Mejoza ima dve delitvi in ustvari štiri različne haploidne celice. Pri mitozi se crossing-over ne zgodi, pri mejozi pa je ključen za genetsko raznolikost.
Glavna razlika v anafazi: pri mitozi se ločijo sestrski kromatidi, pri mejozi I pa homologni kromosomi. Šele v mejozi II se ločijo sestrski kromatidi.
Genetska variabilnost nastane zaradi dveh procesov: crossing-over v profazi I (rekombinacija genov) in neodvisno razvrščanje homolognih kromosomov v metafazi I.
Če se kaj zalomi pri mejozi (nerazdvajanje kromosomov), lahko nastanejo gamete z napačnim številom kromosomov. To vodi do genetskih motenj, kot je Downov sindrom.
💡 Za test: Ključna razlika je v anafazi I - ločujejo se homologni kromosomi, ne sestrski kromatidi!
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Spermatogeneza vs. oogeneza
Pri moških in ženskah se mejoza izvaja malo drugače, čeprav je osnovni proces enak.
Pri spermatogenezi (tvorba spermija) iz ene celice nastanejo štirje funkcionalni spermiji. Vsi štirje so približno enako veliki in vsi lahko oplodijo jajčno celico.
Pri oogenezi (tvorba jajčnih celic) pa iz ene celice nastane le ena velika funkcionalna jajčna celica in tri majhna polarna telesca, ki propadejo. Jajčna celica dobi skoraj vso citoplazmo, ker potrebuje zaloge hranil za razvoj zarodka.
Ta razlika je smiselna - spermiji morajo biti majhni in gibljivi za plavanje, jajčna celica pa velika z zalogami za hranjenje zarodka po oploditvi.
Napake pri mejozi lahko vodijo do gamet z napačnim številom kromosomov. Ko se takšna gameta oplodi, lahko nastanejo genetske motnje, kot je trisomija 21.
💡 Zanimivost: Ženska se rodi z vsemi jajčnimi celicami, ki jih bo imela v življenju - te celice lahko čakajo desetletja, da dokončajo mejozo!
Sign up to see the contentIt's free!
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Improve your grades
Join milions of students
We thought you’d never ask...
What is the Knowunity AI companion?
Our AI Companion is a student-focused AI tool that offers more than just answers. Built on millions of Knowunity resources, it provides relevant information, personalised study plans, quizzes, and content directly in the chat, adapting to your individual learning journey.
Where can I download the Knowunity app?
You can download the app from Google Play Store and Apple App Store.
Is Knowunity really free of charge?
That's right! Enjoy free access to study content, connect with fellow students, and get instant help – all at your fingertips.
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App Store
4.7/5
Google Play
The app is very easy to use and well designed. I have found everything I was looking for so far and have been able to learn a lot from the presentations! I will definitely use the app for a class assignment! And of course it also helps a lot as an inspiration.
Stefan S
iOS user
This app is really great. There are so many study notes and help [...]. My problem subject is French, for example, and the app has so many options for help. Thanks to this app, I have improved my French. I would recommend it to anyone.
Samantha Klich
Android user
Wow, I am really amazed. I just tried the app because I've seen it advertised many times and was absolutely stunned. This app is THE HELP you want for school and above all, it offers so many things, such as workouts and fact sheets, which have been VERY helpful to me personally.
Anna
iOS user
Best app on earth! no words because it’s too good
Thomas R
iOS user
Just amazing. Let's me revise 10x better, this app is a quick 10/10. I highly recommend it to anyone. I can watch and search for notes. I can save them in the subject folder. I can revise it any time when I come back. If you haven't tried this app, you're really missing out.
Basil
Android user
This app has made me feel so much more confident in my exam prep, not only through boosting my own self confidence through the features that allow you to connect with others and feel less alone, but also through the way the app itself is centred around making you feel better. It is easy to navigate, fun to use, and helpful to anyone struggling in absolutely any way.
David K
iOS user
The app's just great! All I have to do is enter the topic in the search bar and I get the response real fast. I don't have to watch 10 YouTube videos to understand something, so I'm saving my time. Highly recommended!
Sudenaz Ocak
Android user
In school I was really bad at maths but thanks to the app, I am doing better now. I am so grateful that you made the app.
Greenlight Bonnie
Android user
very reliable app to help and grow your ideas of Maths, English and other related topics in your works. please use this app if your struggling in areas, this app is key for that. wish I'd of done a review before. and it's also free so don't worry about that.
Rohan U
Android user
I know a lot of apps use fake accounts to boost their reviews but this app deserves it all. Originally I was getting 4 in my English exams and this time I got a grade 7. I didn’t even know about this app three days until the exam and it has helped A LOT. Please actually trust me and use it as I’m sure you too will see developments.
Xander S
iOS user
THE QUIZES AND FLASHCARDS ARE SO USEFUL AND I LOVE Knowunity AI. IT ALSO IS LITREALLY LIKE CHATGPT BUT SMARTER!! HELPED ME WITH MY MASCARA PROBLEMS TOO!! AS WELL AS MY REAL SUBJECTS ! DUHHH 😍😁😲🤑💗✨🎀😮
Elisha
iOS user
This apps acc the goat. I find revision so boring but this app makes it so easy to organize it all and then you can ask the freeeee ai to test yourself so good and you can easily upload your own stuff. highly recommend as someone taking mocks now
Paul T
iOS user
The app is very easy to use and well designed. I have found everything I was looking for so far and have been able to learn a lot from the presentations! I will definitely use the app for a class assignment! And of course it also helps a lot as an inspiration.
Stefan S
iOS user
This app is really great. There are so many study notes and help [...]. My problem subject is French, for example, and the app has so many options for help. Thanks to this app, I have improved my French. I would recommend it to anyone.
Samantha Klich
Android user
Wow, I am really amazed. I just tried the app because I've seen it advertised many times and was absolutely stunned. This app is THE HELP you want for school and above all, it offers so many things, such as workouts and fact sheets, which have been VERY helpful to me personally.
Anna
iOS user
Best app on earth! no words because it’s too good
Thomas R
iOS user
Just amazing. Let's me revise 10x better, this app is a quick 10/10. I highly recommend it to anyone. I can watch and search for notes. I can save them in the subject folder. I can revise it any time when I come back. If you haven't tried this app, you're really missing out.
Basil
Android user
This app has made me feel so much more confident in my exam prep, not only through boosting my own self confidence through the features that allow you to connect with others and feel less alone, but also through the way the app itself is centred around making you feel better. It is easy to navigate, fun to use, and helpful to anyone struggling in absolutely any way.
David K
iOS user
The app's just great! All I have to do is enter the topic in the search bar and I get the response real fast. I don't have to watch 10 YouTube videos to understand something, so I'm saving my time. Highly recommended!
Sudenaz Ocak
Android user
In school I was really bad at maths but thanks to the app, I am doing better now. I am so grateful that you made the app.
Greenlight Bonnie
Android user
very reliable app to help and grow your ideas of Maths, English and other related topics in your works. please use this app if your struggling in areas, this app is key for that. wish I'd of done a review before. and it's also free so don't worry about that.
Rohan U
Android user
I know a lot of apps use fake accounts to boost their reviews but this app deserves it all. Originally I was getting 4 in my English exams and this time I got a grade 7. I didn’t even know about this app three days until the exam and it has helped A LOT. Please actually trust me and use it as I’m sure you too will see developments.
Xander S
iOS user
THE QUIZES AND FLASHCARDS ARE SO USEFUL AND I LOVE Knowunity AI. IT ALSO IS LITREALLY LIKE CHATGPT BUT SMARTER!! HELPED ME WITH MY MASCARA PROBLEMS TOO!! AS WELL AS MY REAL SUBJECTS ! DUHHH 😍😁😲🤑💗✨🎀😮
Elisha
iOS user
This apps acc the goat. I find revision so boring but this app makes it so easy to organize it all and then you can ask the freeeee ai to test yourself so good and you can easily upload your own stuff. highly recommend as someone taking mocks now
Paul T
iOS user