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Nucleotides (bases) are matched to synthesize the new partner strands into two new double helices. In molecular biology, [1] [2] [3] DNA replication is the biological process of producing two identical replicas of DNA from one original DNA molecule. [4] DNA replication occurs in all living organisms acting as the most essential part of ...
In eukaryotes, the vast majority of DNA synthesis occurs during S phase of the cell cycle, and the entire genome must be unwound and duplicated to form two daughter copies. During G 2, any damaged DNA or replication errors are corrected. Finally, one copy of the genomes is segregated into each daughter cell at the mitosis or M phase. [2]
This arrangement of two nucleotides binding together across the double helix (from six-carbon ring to six-carbon ring) is called a Watson-Crick base pair. DNA with high GC-content is more stable than DNA with low GC-content. A Hoogsteen base pair (hydrogen bonding the 6-carbon ring to the 5-carbon ring) is a rare variation of base-pairing. [26]
Nucleotides that have been joined to form polynucleotides can act as a DNA template for one form of DNA synthesis - PCR - to occur. DNA replication also works by using a DNA template, the DNA double helix unwinds during replication, exposing unpaired bases for new nucleotides to hydrogen bond to.
The rate of semiconservative DNA replication in a living cell was first measured as the rate of the T4 phage DNA strand elongation in phage-infected E. coli. [10] During the period of exponential DNA increase at 37 °C, the rate of strand elongation was 749 nucleotides per second.
The eukaryotic cell cycle consists of four distinct phases: G 1 phase, S phase (synthesis), G 2 phase (collectively known as interphase) and M phase (mitosis and cytokinesis). M phase is itself composed of two tightly coupled processes: mitosis, in which the cell's nucleus divides, and cytokinesis, in which the cell's cytoplasm and cell membrane divides forming two daughter cells.
This replication is slow, and sometimes about 100 nucleotides per second are added. We take from this that prokaryotic cells are simpler in structure, they have no nucleus, organelles, and very little of DNA, in the form of a single chromosome. Eukaryotic cells have nucleus with multiple organelles and more DNA arranged in linear chromosomes.
The two main classes of nucleic acids are deoxyribonucleic acid (DNA) and ribonucleic acid (RNA). If the sugar is ribose, the polymer is RNA; if the sugar is deoxyribose, a variant of ribose, the polymer is DNA. Nucleic acids are chemical compounds that are found in nature. They carry information in cells and make up genetic material.