Cells, like these prokaryotic E. coli cells, replicate themselves quickly and efficiently. Part of the process of asexual reproduction is the ability of cells to make identical copies of their of their DNA before cell division occurs. Prokaryotic cells that reproduce by binary fission rely on the fast, accurate process of DNA replication to ensure future generation of cells will have the same genetic instructions as the parent cell. The structure of DNA aids in the speed and accuracy of replication. Double stranded DNA is a polymer of two strands of nucleotides which are hydrogen bonded to each other to form a double helix. Nucleotides are molecules that consist of a deoxyribose sugar, a phosphate and one of four nitrogenous bases. The phosphodiester backbones consist of alterating sugar and phosphate groups. The nitrogenous bases include cytosine, thymine, adenine, and guanine. Cytosine forms three hydrogen bonds with guanine and thymine forms two hydrogen bonds with adenine. This is referred to as complementary base pairing, The double helix will have one strand oriented in a 5'-3' direction relative to the hydroxyl group of the deoxyribose sugar, and the other strand oriented in a 3'-5' direction. This shows the antiparallel nature of the DNA strands. The complementary base pairing in the structure of DNA allows replication to be executed in a semi-conservative manner . Each strand of the DNA molecule is used as a template in the creation of a new double strand. Replication begins with double stranded DNA being separated and each original strand, cells a parent strand, is used as a template for the complementary base pairing of nucleotides to make two new molecules. DNA replication occurs in the 5' to 3' direction, adding new nucleotides to the 3' end of the newly forming strand. DNA repilcation will begin at a specific area of the molecule called the origin of replication. The origin or replication denotes the area of active replication called the replication fork. In order to understand how complex eukaryotic organisms replicate DNA, scientists first studied replication in prokaryotic models, like E. coil. A numder of enzymes are needed for replication to proceed once the replication fork is established. Helicase separates the strands of the double helix and single stranded binding proteins stabllize the newly stranded