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In molecular biology, origin recognition complex (ORC) is a multi-subunit DNA binding complex (6 subunits) that binds in all eukaryotes and archaea in an ATP-dependent manner to origins of replication. The subunits of this complex are encoded by the ORC1, ORC2, ORC3, ORC4, ORC5 and ORC6 genes.
Binding of the cell division cycle 6 (Cdc6) protein to the origin recognition complex (ORC) is an essential step in the assembly of the pre-replication complex (pre-RC) at the origins of replication. Cdc6 binds to the ORC on DNA in an ATP-dependent manner, which induces a change in the pattern of origin binding that requires Orc1 ATPase . [ 23 ]
The challenge for abiogenesis (origin of life) [7] [8] [9] researchers is to explain how such a complex and tightly interlinked system could develop by evolutionary steps, as at first sight all its parts are necessary to enable it to function. For example, a cell, whether the LUCA or in a modern organism, copies its DNA with the DNA polymerase ...
Eukaryogenesis, the process which created the eukaryotic cell and lineage, is a milestone in the evolution of life, since eukaryotes include all complex cells and almost all multicellular organisms. The process is widely agreed to have involved symbiogenesis , in which an archeon and a bacterium came together to create the first eukaryotic ...
The underlying hypothesis held by Oparin, Haldane, Bernal, Miller and Urey, for instance, was that multiple conditions on the primeval Earth favoured chemical reactions that synthesized the same set of complex organic compounds from such simple precursors. Bernal coined the term biopoiesis in 1949 to refer to the origin of life. [33]
The evolution of biological complexity is one important outcome of the process of evolution. [1] Evolution has produced some remarkably complex organisms – although the actual level of complexity is very hard to define or measure accurately in biology, with properties such as gene content, the number of cell types or morphology all proposed as possible metrics.
In a Lockean view, there are really two types of ideas: complex and simple. Simple ideas are the building blocks for more complex ideas, and "While the mind is wholly passive in the reception of simple ideas, it is very active in the building of complex ideas…" [11] Complex ideas, therefore, can either be modes, substances, or relations.
This early, simple form of genetic recovery is similar to that occurring in extant segmented single-stranded RNA viruses (see influenza A virus). As duplex DNA became the predominant form of the genetic material, the mechanism of genetic recovery evolved into the more complex process of meiotic recombination, found today