mitosis/meiosis with 3n organism

[Oh_Gee]

assuming mendelian inheritance, would 3n mitosis mean you get 2^3 daughter cells? how would meiosis work?

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[DrDreams]

2n-->4 daughter cells
I think you just get 2 extra cells don't you?

The difference is just 1 chromosome additional.

for a 2n you get 4 daughter cells and so for a 3n you must get 6. Thats how I am thinking of it.

 

[Oh_Gee]

hmm. so in 2n mitosis, say you have chromosome K with 1 copy each from mother and father. the 2 daughter cells will have also have 1 copy K from mother and father. that's what 2n means right?

now in 3n mitosis, you would have chromosome R with 3 different copies. i guess there'd be 2 daughter cells each with 3 different copies of R?

 

[DrDreams]

So this was confusing to me to. So when each cell has a chromosome from both parents, its 2n, even if its a tetrad(because its still has the pair from mom and dad but each pair now has sister chromatids) its still a 2n.

The result of meiosis is that each cell has 1/2 pair (or just 1 copy rather than 1 from mom and dad) each cell may RANDOMLY have number 1 from dad 2 from mom and 3 from mom and 4 from dad etc. Thats the genetic variability.

But the end result is, that you had tetrads, and hence 4 cells in meiosis.

But mitosis would just be sister chromatids split and create another 2n cell. So both cells will remain 2n.

 

[kraskadva]

2n-->4 daughter cells
I think you just get 2 extra cells don't you?

The difference is just 1 chromosome additional.

for a 2n you get 4 daughter cells and so for a 3n you must get 6. Thats how I am thinking of it.

no.
You still get 2 (or 4) daughter cells for mitosis (or meiosis).

Mitosis works the same way i.e. double then split.
Meiosis gets weird and all sorts of polyploidy or aneuploidy occurs. In plants this happens all the time like its no thing, and you can end up with enormous genomes. In mammalian cells, the SHTF and it won't make viable zygotes.

I wouldn't worry about the details much though, as you're highly unlikely to see anything about this on the MCAT, or anywhere outside of plant genetics for that matter.

 

[DrDreams]

Thanks for clarifying kraskadva.

BTW here is where i got clarification prior http://mcat-review.org/genetics.php

 

[DrDreams]

no.
You still get 2 (or 4) daughter cells for mitosis (or meiosis).

Mitosis works the same way i.e. double then split.
Meiosis gets weird and all sorts of polyploidy or aneuploidy occurs. In plants this happens all the time like its no thing, and you can end up with enormous genomes. In mammalian cells, the SHTF and it won't make viable zygotes.

I wouldn't worry about the details much though, as you're highly unlikely to see anything about this on the MCAT, or anywhere outside of plant genetics for that matter.

BTW so that means you won't have a meiosis 3 stage right?

 

[Oh_Gee]

no.
You still get 2 (or 4) daughter cells for mitosis (or meiosis).

Mitosis works the same way i.e. double then split.
Meiosis gets weird and all sorts of polyploidy or aneuploidy occurs. In plants this happens all the time like its no thing, and you can end up with enormous genomes. In mammalian cells, the SHTF and it won't make viable zygotes.

I wouldn't worry about the details much though, as you're highly unlikely to see anything about this on the MCAT, or anywhere outside of plant genetics for that matter.

so is DrDreams right about

"The result of meiosis is that each cell has 1/2 pair (or just 1 copy rather than 1 from mom and dad) each cell may RANDOMLY have number 1 from dad 2 from mom and 3 from mom and 4 from dad etc. Thats the genetic variability."?

also what is SHTF

 

[kraskadva]

hmm. so in 2n mitosis, say you have chromosome K with 1 copy each from mother and father. the 2 daughter cells will have also have 1 copy K from mother and father. that's what 2n means right?

now in 3n mitosis, you would have chromosome R with 3 different copies. i guess there'd be 2 daughter cells each with 3 different copies of R?

yes.

BTW so that means you won't have a meiosis 3 stage right?

correct, there is no meiosis 3. ever.

 

[DrDreams]

so is DrDreams right about

"The result of meiosis is that each cell has 1/2 pair (or just 1 copy rather than 1 from mom and dad) each cell may RANDOMLY have number 1 from dad 2 from mom and 3 from mom and 4 from dad etc. Thats the genetic variability."?

also what is SHTF

I understand that to be the law of independent assortment...correct me if I'm wrong. Genetics is not my strength.

 

[Oh_Gee]

i only made this thread because i was thinking like a test writer

"hmmm how can I mess with this guy's head"

no.
You still get 2 (or 4) daughter cells for mitosis (or meiosis).

Mitosis works the same way i.e. double then split.
Meiosis gets weird and all sorts of polyploidy or aneuploidy occurs. In plants this happens all the time like its no thing, and you can end up with enormous genomes. In mammalian cells, the SHTF and it won't make viable zygotes.

I wouldn't worry about the details much though, as you're highly unlikely to see anything about this on the MCAT, or anywhere outside of plant genetics for that matter.

how do plant mitosis/meiosis work if their polyploidy. mitosis would be the same right? if you have 14n plant cell, you would still get 14n daughter cells?

 

[kraskadva]

so is DrDreams right about

"The result of meiosis is that each cell has 1/2 pair (or just 1 copy rather than 1 from mom and dad) each cell may RANDOMLY have number 1 from dad 2 from mom and 3 from mom and 4 from dad etc. Thats the genetic variability."?

also what is SHTF

SHTF= **** hits the fan. very technical, scientific term

"The result of meiosis is that each cell has 1/2 pair (or just 1 copy rather than 1 from mom and dad) each cell may RANDOMLY have number 1 from dad 2 from mom and 3 from mom and 4 from dad etc. Thats the genetic variability."?
took me three times to read that, but yes... independent assortment.

Ok, basic mnemonic:
Mitosis happens in my toes, meiosis happens in my Os

Mitosis is cells dividing to grow/replace. 2n doubles, then halves. You get 2 daughter cells identical to each other and to the original cell.

Meiosis is all about the next generation (so it happens in the Ovaries and the Orchi {testes})
Cells double (2n to 4n) then half (meiosis 1) then half again (meiosis 2) leaving 1n. whether the daughter cell ended up with grandma's copy of the gene or grandpa's copy of the gene is totally random. (grandma/grandpa because mom (or dad) has one copy from each parent)
Also, crossing over happens here, so a single chromosome in the daughter cell will be a jumble of grandma & grandpa's DNA.

 

[kraskadva]

i only made this thread because i was thinking like a test writer

"hmmm how can I mess with this guy's head"



how do plant mitosis/meiosis work if their polyploidy. mitosis would be the same right? if you have 14n plant cell, you would still get 14n daughter cells?

lol, ok good, because I was wondering about you...

in plants mitosis is the same, & the steps of meiosis are the same (but there can be some non-disjunction). The biggest difference will be whether the seeds are viable or not after fertilization. Plants tend to handle all this pretty well though. Which is why you see so many hybrids.
But really don't worry about this, it won't come up.

 

[kraskadva]

Thanks for clarifying kraskadva.

BTW here is where i got clarification prior http://mcat-review.org/genetics.php

Yeah, that's a fairly comprehensive list of what you need to know.