Autonomous replication

Extrachromosomal autonomously replicating circular closed DNA molecules encoding non-essential supplementary genetic information, like antibiotic resistance or metabolic capacities. 

ARS Autonomously replicating sequence the origin of replication in yeast. 

A vector (or cloning vector) is any DNA molecule (or fragment) capable of autonomous replication within a host cell into which other DNA sequences can be inserted and thus amplified. 

To clone the restriction fragments, they must each be inserted into a vector. A vector is a piece of DNA (plasmid, viral chromosome, yeast chromosome) capable of autonomous replication in a host cell, for instance, the plasmid pBR322 shown in Figure 1-6-3. The DNA used as a vector usually has... 

A fundamental shortcoming should also be borne in mind transgenic organisms are made by altering one or a few genes, while it is the cell that has fiill attributes of autonomous replication. Further, in multicellular organisms this occurs in cooperation among differentiated cells. 

A vector is a molecule of DNA to which the fragment of DNA to be cloned is joined. Essential properties of a vector include 1) it must be capable of autonomous replication within a host cell, 2) it must contain at least one specific nucleotide sequence recognized by a restriction endonuclease, and 3) it must carry at least one gene that confers the ability to select for the vector, such as an antibiotic resistance gene. Commonly used vectors include plasmids and bacterial and animal viruses. 

In a simple procedure for DNA cloning, an autonomously replicating plasmid and insert DNA are cut with a restriction enzyme and then the pieces are annealed and covalently joined by the action of DNA ligase. The resulting recombinant molecules are then transfected into E. coli, where they replicate. When plasmid vectors are used, a population of permeabilized cells is bathed in the plasmid DNA containing the inserted DNA. Because only a small number of cells become transfected by this procedure, a way to se-... 

Replicon. A genetic element that behaves as an autonomous replicating unit. It can be a plasmid, phage, or bacterial chromosome. 

Further examples of plasmids (autonomously replicating extranuclear DNA) emerged through the 1950s and 1960s (see Day and Poulton, 1996) those for drug... 

The size of the genomic DNA in eukaryotic cells (such as the cells of yeast, plants, or mammals) is much larger (up to 10+11 base pairs) than in E. coli (ca. 10+6 base pairs). The rate of the eukaryotic replication fork movement is about fifty nucleotides per second, which is about ten times slower than in E. coli. To complete replication in the relatively short time periods observed, multiple origins of replication are used. In yeast cells, these multiple origins of replication are called autonomous replication sequences (ARSs). As with prokaryotic cells, eukaryotic cells have multiple DNA polymerases. DNA polymerase S, complexed with a protein called proliferating... 

Plasmids are autonomously replicating pieces of extrachromosomal DNA present in bacteria. They are encoded with subtle, yet vital, changes for the synthesis of important cellular proteins. Because they are relatively large, they can contain information pertaining to several genes. One of these genes codes for beta-lactamase, an enzyme that can hydrolyze the four-member heterocyclic beta-lactam ring present in penicillins and cephalosporins. 

Most progress in understanding this has been made in the yeast Saccharomyces cerevisiae from the chromosomes of which sequences have been identified that allow initiation of replication when inserted into plasmids (see below). These sequences are called autonomously replicating sequences (ARSs). It is likely that some of them, at least, represent bona fide replication origins. Presumably the mechanism of initiation at these origins is similar to that which has been elucidated in bacteria. 

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