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Eukaryotic origins of replication control the formation of several protein complexes that lead to the assembly of two bidirectional DNA replication forks. These events are initiated by the formation of the pre-replication complex (pre-RC) at the origins of replication. This process takes place in the G 1 stage of the cell cycle. The pre-RC ...
In eukaryotes, DNA replication takes place in the nucleus. A plethora replication form in just one replicating DNA molecule, the start of DNA replication is moved away by the multi-subunit protein. This replication is slow, and sometimes about 100 nucleotides per second are added.
Within eukaryotes, DNA replication is controlled within the context of the cell cycle. As the cell grows and divides, it progresses through stages in the cell cycle; DNA replication takes place during the S phase (synthesis phase). The progress of the eukaryotic cell through the cycle is controlled by cell cycle checkpoints.
In molecular biology, endonucleases are enzymes that cleave the phosphodiester bond within a polynucleotide chain (namely DNA or RNA).Some, such as deoxyribonuclease I, cut DNA relatively nonspecifically (with regard to sequence), while many, typically called restriction endonucleases or restriction enzymes, cleave only at very specific nucleotide sequences.
DNA gyrase, or simply gyrase, is an enzyme within the class of topoisomerase and is a subclass of Type II topoisomerases [1] that reduces topological strain in an ATP dependent manner while double-stranded DNA is being unwound by elongating RNA-polymerase [2] or by helicase in front of the progressing replication fork.
Many important cell functions take place in the nucleus, more specifically in the nucleoplasm. The main function of the nucleoplasm is to provide the proper environment for essential processes that take place in the nucleus, serving as the suspension substance for all organelles inside the nucleus, and storing the structures that are used in ...
DNA is a duplex formed by two anti-parallel strands. Following Meselson-Stahl, the process of DNA replication is semi-conservative, whereby during replication the original DNA duplex is separated into two daughter strands (referred to as the leading and lagging strand templates). Each daughter strand becomes part of a new DNA duplex.
Before replication can take place, an enzyme called helicase unwinds the DNA molecule from its tightly woven form, in the process breaking the hydrogen bonds between the nucleotide bases. This opens up or "unzips" the double-stranded DNA to give two single strands of DNA that can be used as templates for replication in the above reaction.