Summary:
- Chromosomes are the form of the genetic material of a cell during cell division.
- Chromosomes form after DNA replicates; prior to replication, DNA exists as chromatin.
- Human cells normally have two sets of chromosomes, one set inherited from each parent.
- There are 23 chromosomes in each set, for a total of 46 chromosomes per cell.
- Each chromosome in one set is matched by a chromosome of the same type in the other set.
- Most genes contain the instructions for a single protein.
- There may be hundreds or even thousands of genes on a single chromosome.