Chromosomes in the nucleus of a cell contain information for inheritance of features from parents to next generation in the form of DNA molecules. The DNA in the cell nucleus is the information source for making proteins. If the information is changes, different proteins will be made. Different proteins will eventually lead to altered body designs. Therefore, a basic event in reproduction is the creation of a DNA copy.
DNA copying is accompanied by the creation of an additional cellular apparatus and then the DNA copies separate each with its own cellular apparatus. Effectively a cell divides to give rise to two cells.
The process of copying the DNA will have some variations each time. As a result the DNA copies generated will be similar but may not be identical to the original.
