DNA replication is important because it creates a second copy of DNA that must go into one of the two daughter cells when a cell divides. Without replication, each cell lacks enough genetic material to provide instructions for creating proteins essential for bodily function.
DNA is generally tightly packed into a structure called chromatin. It is double stranded and twisted into a structure called a double helix. In order to replicate, DNA must unwind. After unwinding, each side of DNA separates by unzipping down the middle, with the two unzipped strands serving as templates for creating new strands. At the end of replication, the two new segments of DNA each contain one old and one new strand.
Replication occurs at different rates in different types of cells. Some cells continuously divide and must constantly replicate their DNA. Other cells divide at a much slower rate and do not need to replicate their DNA as often. Some cells divide until the organ they make up reaches its normal size, and then they do not divide again.
DNA stands for deoxyribonucleic acid. Each strand of DNA is made up of a sugar, a phosphate and a nitrogenous base bonded together into a structure called a nucleotide. Many nucleotides bond together to form DNA.