structure and behaviour of chromosomes during meiosis (1 Viewer)

[league_girl]

this dot point is extremely confusing. i understand the different stages of the process but i am confused as to how many chromosones are involved are we talking 2n=46, 32 or just the sex chromosones??!?!?! wha??!?!


PLEASE HELP!:burn:

 

[Dr_Doom]

46 / 2 = 23 (22 somatic, 1 sex cell (either X or Y)).

prophase - chromosomes get thicker
metaphase - chromosomes randomly assort with their matchin pairs (Eg/ AB or aB or Ab or ab)
anaphase - chromosomes start to seperate and head toward opposite poles
telephase - cell starts to split and 2 cells are formed.
process repeats to form 4 daughter cells each with haploid number of chromosomes (23).

chromosomes can also cross over which increases genetic diversity

so chromosomes:
cross over
independent assortment / random segregation

to remember the processes in meiosis:

IP MAT

interphase
prophase
metaphase
anaphase
telephase

 

[Ea22.007]

in humans b4 meiosis 1 u have 92 chromatids as they have replicated in the S phase

but then they become 2n=46 in each cell after meiosis 1

and then n=23 chromosomes are in each daughter cell after meiosis 2

the crossing over bit happens in meiosis 1

 

[Princess Court]

I also have a question sorta similar: at the end of meiosis what are two process which could result in different gametes occuring and draw a diagarm to illustrate what gametes would result.

Can anyone please help me with this???

 

[Dr_Doom]

46 / 2 = 23 (22 somatic, 1 sex cell (either X or Y)).

prophase - chromosomes get thicker
metaphase - chromosomes randomly assort with their matchin pairs (Eg/ AB or aB or Ab or ab)
anaphase - chromosomes start to seperate and head toward opposite poles
telephase - cell starts to split and 2 cells are formed.
process repeats to form 4 daughter cells each with haploid number of chromosomes (23).

chromosomes can also cross over which increases genetic diversity

so chromosomes:
cross over
independent assortment / random segregation

to remember the processes in meiosis:

IP MAT

interphase
prophase
metaphase
anaphase
telephase

Thanks man, I totally forgot all that!

 

[JCDenton]

Two process which could result in different gametes occuring are random segrigation and crossing over

Random segrigation: When creating only one zygote, only two gametes are required to do so, however, there are more than one different groups of chromosomes that make up different gametes.
This means that the chromosomes the gamete gets durring meiosis are completely random, giving thousands of different comibinations of chromosomes.
This gives different gametes.

Crossing over: This is very common in meiosis. When the Chromosomes are in their homologus pairs, the genetic code from one of the pairs of "arms" become wound up like rope and finally break off, switching the code in the DNA. This will only happen with whole parts of the genes, so all the genes are there, just in different coding.