It ensures that each newcell will be an exactcopy of its parent cell.
Chromosomes must be copied before cells divide because it ensures that each cell will be an exact copy of its parent cell. How a cell makes more cells depends on whether the cell is prokaryotic ( has no nucleus ) or eukaryotic ( has a nucleus ) .
Chromosomes must replicate so that both cells that are formed from cell division can have the same genetic material.
Chromosomes must replicate so that both cells that are formed from cell division can have the same genetic material.
If a cell divides by mitosis both cells will have the diploid (2N) number of chromosomes. These two cells will have identical DNA If a cell divides by meiosis subsequent cells will have the haploid (1N) number of chromosomes. These cells will have the same basic amount of DNA but the DNA will not be identical. If the sex chromosomes are different sizes (like the X and Y chromosomes of humans) the DNA will vary a bit more dramatically if the meiosis includes the additional variation of the different sex chromosomes.
Twice the number in the cell. So if the cell normally has 46 chromosomes, such as in somatic human cells, the dividing cell would have 92 chromosomes just before division. With germ cells such as sperm and egg this would be half that. Sperm and egg cells in humans would contain 23 chromosomes and 46 just before division.With N representing the number of chromosomes in an organism:Mitosis (somatic cells) 2N -> 4N division -> 2N
Before mitosis begins, the chromosomes and other materials are copied. The pair of centrioles which are also copied. Each chromosome now consist of two chromatids.
DNA must be copied before cell division so that one complete copy of each chromosome ends up in each of the two daughter cells. Otherwise only one cell would end up with DNA, making the other cell.. well.. not a cell.
when the chromosomes are replicated the cells were about to divide into 2 cells (mitosis)
They copy their chromosomes so that when they do divide into two different cells each one will have its own set of chromosomes and it couldn't be copied and transferred after divison occured
the chromosomes are replicated (copied) and are compacted into dense visible structures
After Mitosis, the result is 2 new, identical, daughter cells. In order for each to be identical, the chromosomes must be copied.
If a cell divides by mitosis both cells will have the diploid (2N) number of chromosomes. These two cells will have identical DNA If a cell divides by meiosis subsequent cells will have the haploid (1N) number of chromosomes. These cells will have the same basic amount of DNA but the DNA will not be identical. If the sex chromosomes are different sizes (like the X and Y chromosomes of humans) the DNA will vary a bit more dramatically if the meiosis includes the additional variation of the different sex chromosomes.
Meiosis
Twice the number in the cell. So if the cell normally has 46 chromosomes, such as in somatic human cells, the dividing cell would have 92 chromosomes just before division. With germ cells such as sperm and egg this would be half that. Sperm and egg cells in humans would contain 23 chromosomes and 46 just before division.With N representing the number of chromosomes in an organism:Mitosis (somatic cells) 2N -> 4N division -> 2N
The DNA and chromosomes divide with it
Before mitosis begins, the chromosomes and other materials are copied. The pair of centrioles which are also copied. Each chromosome now consist of two chromatids.
Chromosomes
To make all cells identical.
when the chromosomes are replicated the cells were about to divide into 2 cells (mitosis)
DNA must be copied before cell division so that one complete copy of each chromosome ends up in each of the two daughter cells. Otherwise only one cell would end up with DNA, making the other cell.. well.. not a cell.