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Yeast artificial chromosomes (YACs) are genetically engineered chromosomes derived from the DNA of the yeast, Saccharomyces cerevisiae, which is then ligated into a bacterial plasmid. By inserting large fragments of DNA, from 100–1000 kb, the inserted sequences can be cloned and physically mapped using a process called chromosome walking .
Cloning is generally first performed using Escherichia coli, and cloning vectors in E. coli include plasmids, bacteriophages (such as phage λ), cosmids, and bacterial artificial chromosomes (BACs). Some DNA, however, cannot be stably maintained in E. coli , for example very large DNA fragments, and other organisms such as yeast may be used.
Artificial chromosome may refer to: Yeast artificial chromosome; Bacterial artificial chromosome; Human artificial chromosome; P1-derived artificial chromosome; Synthetic DNA of a base pair size comparable to a chromosome
Yeast genes are classified using gene symbols (such as Sch9) or systematic names. In the latter case the 16 chromosomes of yeast are represented by the letters A to P, then the gene is further classified by a sequence number on the left or right arm of the chromosome, and a letter showing which of the two DNA strands contains its coding sequence.
A total of 1,078 cassettes were built, each 1,080 base pairs long. These cassettes were designed in a way that the end of each DNA cassette overlapped by 80 base pairs. The whole assembled genome was transplanted in yeast cells and grown as yeast artificial chromosome. [36]
Next, the desired contents of the minichromosome must be transformed into a host which is capable of assembling the components (typically yeast or mammalian cells [5]) into a functional chromosome. This approach has been attempted for the introduction of minichromosomes into maize for the possibility of genetic engineering, but success has been ...
A human artificial chromosome (HAC) is a microchromosome that can act as a new chromosome in a population of human cells. That is, instead of 46 chromosomes, the cell could have 47 with the 47th being very small, roughly 6–10 megabases (Mb) in size instead of 50–250 Mb for natural chromosomes, and able to carry new genes introduced by human researchers.
At each end of a chromosome lies a "cap" or telomere, as it is known, which protects it. After Elizabeth Blackburn discovered that telomeres have a particular DNA, through experiments conducted on ciliates and yeast, she and Jack Szostak proved in 1982 that the telomeres' DNA prevents chromosomes from being broken down,