something i just absolutely dont get

[TheWhiteFlame]

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about mitosis, DNA replication and karyotypes.


ok. ive never understood this. i mean it hasnt affected my grades, but it bothers the piss out of me.


in any given somatic cell karyotype, you see the chromosomes appear in the standard X formation. ok.

whenever you watch a video on mitosis, whenever the chromosomes are lined up on the metaphase plate, they are said to be "replicated". but, they are STILL in the X formation. when they are pulled apart, the image shows that the NEW CELL only has ONE of each chromatid from each separated chromosome.

so the new cell nucleus seems to contain as

|
|
|
instead of
X
X
X

BUT, each cell is said to have two "pairs" of each chromosome in G1 phase. | isnt a pair, X is.

how does | get to X?


do you understand what im asking?

 

[RogueUnicorn]

oh... my..... god....

 

[patel2]

about mitosis, DNA replication and karyotypes.


ok. ive never understood this. i mean it hasnt affected my grades, but it bothers the piss out of me.


in any given somatic cell karyotype, you see the chromosomes appear in the standard X formation. ok.

whenever you watch a video on mitosis, whenever the chromosomes are lined up on the metaphase plate, they are said to be "replicated". but, they are STILL in the X formation. when they are pulled apart, the image shows that the NEW CELL only has ONE of each chromatid from each separated chromosome.

so the new cell nucleus seems to contain as

|
|
|
instead of
X
X
X

BUT, each cell is said to have two "pairs" of each chromosome in G1 phase. | isnt a pair, X is.

how does | get to X?


do you understand what im asking?

 

[TheWhiteFlame]

oh... my..... god....

that was constructive

 

[TheWhiteFlame]

thats ignorant

 

[Political]

If only life had a homework help forum

 

[obscurehero]

This comes from a popular misconception with the nomenclature.

Each chromosome is actually the _._ little design. When it replicates in S-phase it turns into an X so that the cell now has 4n. When the chromosomes line up on the meta-phase plate there are actually two chromosome 1's (X's) that are duplicated so that when the cells split each cell is 2n. The funny thing is that _._ and X are called chromosomes. However, the X structure is a chromosome with two sister chromatids...weird eh?

This is all explained when you look at a karyotype and you see that the chromosomes aren't always in the traditional X fashion.

This is at least the way I was taught.

 

[TheWhiteFlame]

ok, so taking chromosome one for example.

there are two objects in the image, side by side. these two objects are the "pairs" of chromosomes? so when they replicate, these two "objects" go from || (in the image) to _._ --> replication results in X?


i think i understand now. the two objects in the image of the karyotype join to form one chromatid?

 

[TheWhiteFlame]

If only life had a homework help forum

if you would have read the OP you would have realized this has nothing to do with my homework and is something that just bothers me because i dont completely understand the mechanics

 

[obscurehero]

No..well, kinda right.

You've posted a SORTED karyotype. Each of the _._ replicate and turn into X...the two _._ don't join to become an X. So, during 4n G2/M phase of mitosis you have TWO X's for each chromsome #. So, for chromosome #1 there are two X's during G2/M phase of mitosis.

As for each X, its also called a chromosome (not plural) with two sister chromatidS. When the cell is quiescent or not in mitosis, the chromosomes are in _._ form.

Look at chromosome X and Y for this male karyotype. See how they're not joined? The problem with sorted karyotypes and the nomenclature ambiguity is that the student will tend to think that they are joined in the 'X' form even though they're just sitting next to each other. If you look at a replicating cell (G2/M) karyotype (easily found on google) you can see that there are TWO X's for each Chromosome #.

 

[TheWhiteFlame]

word. i get it now. thanks.

 

[goldenwest]

i dink iz becuz u gottah understand tha the when the things split they make the other haff thing agin or sumtin