DNA Replication

Nearly every cell in a person’s body has the same DNA. Most DNA is located in the cell nucleus, but a small amount of DNA can also be found in the mitochondria. DNA was thought to be a simple molecule, consisting of nucleotides strung together like beads on a string.By the late 1940s biochemists knew that DNA was a very long polymer made up of millions of nucleotides. DNA is made up of two strands and each strand of the original DNA molecule serves as a template for the production of the complementary strand, a process referred to as semi conservative replication. Cellular proofreading and error-checking mechanisms ensure near perfect fidelity for DNA replication. DNA usually exists as a double-stranded structure, with both strands coiled together to form the characteristic double- helix. Each single strand of DNA is a chain of four types of nucleotides. Nucleotides in DNA contain a deoxyribose sugar, a phosphate, and a nucleobase. The four types of nucleotide correspond to the four-nucleobase adenine; cytosine, guanine, and thymine, commonly abbreviated as A, C, G and T. This review was assumed to have the historical background of DNA replicationand major DNA replication steps and its function.