Human artificial chromosome
Encyclopedia
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
in size, and able to carry new genes introduced by human researchers. Yeast artificial chromosome
s and bacterial artificial chromosome
s were created before human artificial chromosomes, which first appeared in 1997
. They are useful in expression studies as gene transfer vector
s and are a tool for elucidating human chromosome function. Grown in HT1080 cells, they are mitotically
and cytogenetically
stable for up to six months.
School of Medicine published the first report of human artificial chromosomes in 1997. They were first synthesized by combining portions of alpha satellite DNA
with telomeric
DNA and genomic DNA into linear microchromosomes.
Microchromosome
A microchromosome is a type of very small chromosome which is a typical component of the karyotype of birds, some reptiles, fish, and amphibians; they tend to be absent in mammals. They are less than 20 Mb in size; chromosomes which are greater than 40 Mb in size are known as macrochromosomes,...
that can act as a new chromosome
Chromosome
A chromosome is an organized structure of DNA and protein found in cells. It is a single piece of coiled DNA containing many genes, regulatory elements and other nucleotide sequences. Chromosomes also contain DNA-bound proteins, which serve to package the DNA and control its functions.Chromosomes...
in a population of human
Human
Humans are the only living species in the Homo genus...
cells. That is, instead of 46 chromosomes, the cell could have 47 with the 47th being very small, roughly 6-10 megabases
Base pair
In molecular biology and genetics, the linking between two nitrogenous bases on opposite complementary DNA or certain types of RNA strands that are connected via hydrogen bonds is called a base pair...
in size, and able to carry new genes introduced by human researchers. Yeast artificial chromosome
Yeast artificial chromosome
A yeast artificial chromosome is a vector used to clone DNA fragments larger than 100 kb and up to 3000 kb. YACs are useful for the physical mapping of complex genomes and for the cloning of large genes...
s and bacterial artificial chromosome
Bacterial artificial chromosome
A bacterial artificial chromosome is a DNA construct, based on a functional fertility plasmid , used for transforming and cloning in bacteria, usually E. coli. F-plasmids play a crucial role because they contain partition genes that promote the even distribution of plasmids after bacterial cell...
s were created before human artificial chromosomes, which first appeared in 1997
1997 in science
The year 1997 in science and technology involved many significant events, listed below.-Astronomy and space exploration:* January 17 - Explosion of a Delta II rocket carrying a military GPS payload shortly after liftoff from Cape Canaveral....
. They are useful in expression studies as gene transfer vector
Vector (molecular biology)
In molecular biology, a vector is a DNA molecule used as a vehicle to transfer foreign genetic material into another cell. The four major types of vectors are plasmids, viruses, cosmids, and artificial chromosomes...
s and are a tool for elucidating human chromosome function. Grown in HT1080 cells, they are mitotically
Mitosis
Mitosis is the process by which a eukaryotic cell separates the chromosomes in its cell nucleus into two identical sets, in two separate nuclei. It is generally followed immediately by cytokinesis, which divides the nuclei, cytoplasm, organelles and cell membrane into two cells containing roughly...
and cytogenetically
Cytogenetics
Cytogenetics is a branch of genetics that is concerned with the study of the structure and function of the cell, especially the chromosomes. It includes routine analysis of G-Banded chromosomes, other cytogenetic banding techniques, as well as molecular cytogenetics such as fluorescent in situ...
stable for up to six months.
History
John J. Harrington, Gil Van Bokkelen, Robert W. Mays, Karen Gustashaw & Huntington F. Willard of Case Western Reserve UniversityCase Western Reserve University
Case Western Reserve University is a private research university located in Cleveland, Ohio, USA...
School of Medicine published the first report of human artificial chromosomes in 1997. They were first synthesized by combining portions of alpha satellite DNA
Satellite DNA
Satellite DNA consists of very large arrays of tandemly repeating, non-coding DNA. Satellite DNA is the main component of functional centromeres, and form the main structural constituent of heterochromatin....
with telomeric
Telomere
A telomere is a region of repetitive DNA sequences at the end of a chromosome, which protects the end of the chromosome from deterioration or from fusion with neighboring chromosomes. Its name is derived from the Greek nouns telos "end" and merοs "part"...
DNA and genomic DNA into linear microchromosomes.
See also
- bacterial artificial chromosomeBacterial artificial chromosomeA bacterial artificial chromosome is a DNA construct, based on a functional fertility plasmid , used for transforming and cloning in bacteria, usually E. coli. F-plasmids play a crucial role because they contain partition genes that promote the even distribution of plasmids after bacterial cell...
(BAC) - yeast artificial chromosomeYeast artificial chromosomeA yeast artificial chromosome is a vector used to clone DNA fragments larger than 100 kb and up to 3000 kb. YACs are useful for the physical mapping of complex genomes and for the cloning of large genes...
(YAC) - plasmidPlasmidIn microbiology and genetics, a plasmid is a DNA molecule that is separate from, and can replicate independently of, the chromosomal DNA. They are double-stranded and, in many cases, circular...
- cosmidCosmidA cosmid, first described by Collins and Hohn in 1978, is a type of hybrid plasmid that contains cos sequences, DNA sequences originally from the Lambda phage. Cosmids can be used to build genomic libraries....
- fosmidFosmidFosmids are similar to cosmids but are based on the bacterial F-plasmid. The cloning vector is limited, as a host can only contain one fosmid molecule. Fosmids are 40 kb of random genomic DNA...