New Chromosomes after Mitosis?

[Guest Siientx]

Normally i don't have any questions about science but this one struck me. My teacher said all cells come from other cells (Cell Theory) so i asked myself. Today we learnt about Mitosis, the dividing of cells to form new cells. In the Metaphase Double Stranded Chromosomes line up on the Spindle Finders and are seperated into one One Stranded Chromosomes by the time the cell divides into two (Telophase). Now how does the two cells continue diving if the Chromosomes are not double stranded? Do they regenerate a new strand for the next dividing, or what?

[psi20]

Chromosomes form when the cell begins to divide. At other times, it's chromatin, which is a "soup of DNA," as my teacher explained. In Prophase, which is before Mitosis, chromosomes duplicate, which is why you get 2 pairs of chromosomes. In DNA, adenine goes with thymine, and guanine go with cytosine, so having one chromosome allows it to make a copy of itself from the base pairs floating around the nucleus of the cell.

[muad'dib]

Before a cell divides it duplicates each chromosome. In humans there are 46 chromosomes in each cell (except in gametes, which have 23), 23 from each parent. This means that each cell has two versions of chromosome 6, and 12, and 2, and so on, one version from each parent. So right after all the chromomsomes are duplicated but before the cell divides there are four versions of chromosome 6; the one from the father and its duplicate, and the one from the mother and its duplicate. When the chromosomes start to move to opposite ends of the cell during ananphase one copy of each chromosome goes to either end. Each end of the cell gets two versions of chromosome 6, the version from the father and the version from the mother.

[mak10]

Now how does the two cells continue diving if the Chromosomes are not double stranded? Do they regenerate a new strand for the next dividing, or what?

 

yes, the DNA replicates and the chromosomes again divide into two chromatids, marking the onset of interphase. this can go on an on, depending on the instructions encoded in your genes. if this instruction is disrupted (like in cancer), then the cell may start dividing uncontrollably and can form unspecialized masses canlled tumors. i don't want wanna into more detail on this but thats basically it.

 

-mak10

[birdo118]

if ur talking about mitosis, the chromatin duplicates during interphase. chromosomes are then established, consisting of two sister chromatids. after anaphase where the chromosomes split and then form the DNA of the new cells. this produces two regular cells.

 

 

if ur talking about meiosis, which you probably are, the chromatin duplicates twice, forming homologus pairs of double-stranded chromosomes. in the first anaphase, the homologus pairs are split, one chromosome going to each of the two cells. after that, normal mitosis occurs and the double stranded chromosomes split and each of the four sister chromatids becomes the DNA of a new cell. this produces 4 sex cells.

[birdo118]

my mistake.....you were asking how cells continue to divide.....they do this by constantly duplicating the chromatin each time the cell needs to divide....this does go on and on, as mak10 said, as long as it needs to......so yes, the chromatin duplictates every time a cell divides

[Auburngirl05]

The cells spend the majority of their time in Interphase, it's divided into a couple of phases itself, and there are checkpoints that function to make sure the cell has duplicated enough material before it begins mitosis. This site gives a pretty good overview, there are tons of online tutorials, too, when I was cramming for the AP Bio test this past spring I found some good ones using a basic Google search.

 

http://biology.about.com/library/weekly/aa071300a.htm