In molecular biology, DNA replication is the biological process of producing two identical DNA replicas from one original DNA molecule. This process occurs in all biological tissues and is the basis of biological inheritance. This cell has a unique cleavage property that necessitates DNA replication. DNA consists of a double helix of two complementary strands. These chains are separate during the copying process. Each strand of the original DNA molecule is then used as a template for the production of its counterpart, a process known as semi-conservative replication. Cell alignment and error checking mechanisms ensure near-perfect fidelity of DNA replication.
In cells, DNA replication begins at a specific location in the genome or at the origin of replication. The origin of DNA and the synthesis of new chains cause the replication fork to grow bidirectionally from the origin. Many proteins are involved in the replication fork and contribute to the initiation and persistence of DNA synthesis. Most notably, DNA polymerases synthesize new chains by adding nucleotides that complement each [template] strand. DNA replication occurs in the S phase of the interval. DNA replication can also be performed in vitro [manually, extracellularly]. DNA polymerase and artificial DNA primers isolated from cells can be used to initiate DNA synthesis in a template DNA molecule with a known sequence. Polymerase chain reaction [PCR] is a common laboratory technique that is periodically applied to amplify specific target DNA fragments from a DNA library. DNA usually exists in a double-stranded structure, and the two strands are coiled together to form a characteristic double helix. Each DNA strand is a chain of four nucleotides. Nucleotides in DNA contain deoxyribose, phosphate and nucleobases.
The four types of nucleotides correspond to four nucleobases adenine, cytosine, guanine and thymine, usually abbreviated as A, C, G and T. adenine and guanine are purine bases, while cytosine And thymine is a pyrimidine. These nucleotides form a phosphodiester bond, producing a phosphate-deoxyribose backbone of the DNA duplex, with the nucleobases pointing inward [ie, toward the opposite strand]. Nucleotides [bases] are matched between the chains by hydrogen bonding to form base pairs. Adenine is paired with thymine [two hydrogen bonds] and guanine is paired with cytosine [stronger: three hydrogen bonds].
The DNA strand is directional, and the different ends of the single strand are called "3' [three proton] ends" and "5' [five proton ends]". Conventionally, if the base sequence of a single-stranded DNA is given, the left end of the sequence is the 5' end, and the right end of the sequence is the 3' end. End. The double helix chains are anti-parallel, one of which is 5' 3' and the opposite chain 3' to 5'. These terms refer to carbon atoms in deoxyribose, to which the next phosphate in the chain is attached. The direction has an effect in DNA synthesis because DNA polymerase can synthesize DNA in only one direction by adding nucleotides at the 3' end of the DNA strand. Pairing of complementary bases in DNA [by hydrogen bonding] means that the information contained in each chain is redundant.
The phosphodiester [intrachain] bond is stronger than the hydrogen [interchain] bond. This allows the strands to be separated from one another. Nucleotides on a single strand can exist prior to use in reconstituting nucleotides on a newly synthesized partner strand. All the DNA structures that need to be known and their replication.
Orignal From: Exploring biology: DNA replication and structure
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