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Discussion Starter · #1 ·
I don't get how a 46/4n cell (after replication) can become two 46/2n cells (after mitosis) and also become two 23/2n cells (after meiosis 1), can some please explain this cytologically or clarify it somehow. thanks
 

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46 4N means that you have replicated your 46 Chromosomes (each chromosome consists of 4 chromatids, not the usual situation which is 2 chromatids).

46 2N is the usual diploid state in all human somatic cells. 23 doubled together each pair consisting of two chromatids.

23 2N is when you halved the chromosomes, now you have only 23 chromosomes, what's called halploid.
 

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Discussion Starter · #3 ·
so the "n" refers to the number of chromatids? In kaplan under embryo meiosis section it says spermatogonia (46/2n) replicate their dna to have 46/4n dna, then undergo meiosis 1 and the daughter cells have 23/2n, shouldn't it be 23/4n because only the chromosomes split, not the chromatids (the 23 chromosomes still have 4 chromatids). Hope this makes sense.
 

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Before both mitosis or meiosis the normal double 23 (46 2N) set get replicated and become (46 4N) which means the same homologous pairs of 23 chromosomes but in two copies.

In mitosis, that's easy. You cut that duplicate in half and so you get each daughter cell having 46 2N.

Just like you in meiosis I don't why they call it 23 2N. :toosad:

this diagram may help

Facial expression Organism Red Font Circle
click to enlarge
 

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Discussion Starter · #5 ·
yeah i got the mitosis part down but even from that diagram, i dont get the meiosis and how it goes from 46/4n to 23/2n and eventually 23/1n, grr
 

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I was taught this by my teacher in 10th or 11th grade but i forgot..the reason behind calling them -daughter chromatids or the daughter cysts...I always thought why girls so special..Why not Son chromosome or the Son cyst....Anyone remember the reason..and for the same reason they always clone to make a daughter..as in dolly the cloned sheep....:confused:
 
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