Eukaryotic cells have many more genes than prokaryotic cells.
These genes have to be copied when cells divide.
Each new daughter cells has to have an exact copy of the genes from the original cell.

The genes are grouped together into chromosomes.
In human cells there are 46 chromosomes.
Each chromosomes contains one very long linear DNA molecule which can contain thousands for genes.

A cell copies its DNA by duplicationg each chromosome.

After replication, each chromosome consists of two sister chromatids. The two sister chromatids are held together by a region called the centromere.

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Key terms: Genes, daughter cells, chromosomes, DNA molecule,chromatin, sister chromatids, centromere

Basic facts: http://homepages.ius.edu/GKIRCHNE/biomolec.htm