Why is DNA copied before mitosis?

Answer 1

DNA has to replicate before mitosis to keep the number of chromosomes and DNA in the cell consistent. Mitosis is the process of reproducing cells by splitting one cell in half to make two. If the DNA didn't replicate, the two daughter cells wouldn't be able to have a complete strand. DNA replicates by dividing in half, then creating a mirror image of itself. Replication gives both strands of DNA an EXACT copy.

For instance, say a cell contains 46 chromosomes (a human body cell). Before dividing in half, it has to double its amount of chromosomes. That way, each offspring cell has the same amount of chromosomes that a normal body cell has. If there weren't the same amount of chromosomes inside all of your body cells, you would have a disability. So, the amount doubles to 92 chromosomes. Then, when the cell splits, each of the offspring again have 46 chromosomes. This is because the chromosomes split equally between the two cells. If it didn't duplicate, the number of chromosomes in each cell would decrease by half each time. This would lead to some cells having a small amount of chromosomes and some cells still having 46. If this occurred, the body would not function properly. This is the same concept with DNA. *REMEMBER* Chromosomes replicate along with the DNA before mitosis begins.

Hope that this helped! :D

Answer 2

Two daughter cells that are genetically identical are formed during the process of mitosis. DNA hence needs to be replicated so that there are two copies of each chromosome for each daughter cell.

Answer 3

Mitosis is asexual reproduction. DNA replication occurs in the S phase of Interphase and this is necessary for the production of the two new Daughter Cells.

A human skill cell has 46 chromosomes. The cell is a parent cell. After Mitosis ends, then each Daughter Cell will still have 46 chromosomes because the DNA replicated and now those two Daughter Cells can begin to replicate as new parent cells. They are exact replications of the parent cell.

Answer 4

If DNA didn't duplicate or copy before mitosis began, an 'empty' cell would be made, as there would be no DNA for this cell to have. Therefore, the cell would be worthless.

Or, in other cases, the DNA from the first cell may halve, so each of the two cells after mitosis have only half the necessary DNA, making both cells useless.

Answer 5

Because mitosis must create an exact copy of the cells, the DNA is duplicated. For meiosis, the resulting diploid zygote (offspring of two gametes) contains 46 chromosomes before becoming haploid (23 chromosomes.) When it splits, this enables the zygote to have the proper chromosomes.

Answer 6

So both cells produced have one copy of all the chromosomes of the original cell

Answer 7

So that the daughter cells are genetically identical to the original cell.