bacterial artificial chromosome & yeast artificial chromosome

BAC & YAC are artificially prepared chromosomes to clone DNA sequences.yeast artificial chromosome is capable of carrying upto 1000 kbp of inserted DNA sequence

1. BAC (Bacterial artificial chromosome) & YAC (Yeast artificial chromosome) PRESENTED BY : ASHA PATEL CLASS: M.Sc SEM 2

2. COMMON GENE COMPONENTS IN BAC RepE : for plasmid replication and regulation of copy number. ParA and parB : for partitioning F plasmid DNA to daughter cells during division and ensures stable maintenance of the BAC. Selectable marker: for antibiotic resistence ; some BACs also have lacZ at the cloning site for blue/white selection. T7 & Sp6: phage promoters for transcription of inserted genes. OriS : the origin of replication

3. MOLECULAR CLONING IN BAC

4. APPLICATION OF BAC BACs are being greatly used in modeling genetic diseases in order to study their effects in the experimentation on transgenic mice. BAC have been used to study neurological diseases such as Alzheimer’s disease or in the case of down syndrome. The genome of several large DNA Viruses and RNA viruses have been cloned as BACs. These constructs are referred to as “infectious clones”.

5. YEAST ARTIFICIAL CHROMOSOME (YAC) First described in 1983 by Murray and Szostak . Yeast artificial chromosomes is a human engineered DNA molecule used to clone DNA sequences in yeast cells. YACs are shuttle vectors capable of replicating and being selected in common bacterial hosts such as E.coli as well as in the yeast S . cerevisiae. They are capable of carrying approximately upto 1000 kbp of inserted DNA sequence. Many different YAC plasmids exist, such as pYAC3 & pYAC4.

6. COMPONENTS OF YAC The vector contains several elements of typical yeast chromosomes including: CEN: A yeast centromere, that ensures chromosome partitioning between two daughter cells and a selective marker genes. ARSI: Yeast autonomously replicating sequence TEL: Yeast telomere Yeast selectable marker such as URA3 & TRP1 and Bacterial selectable marker.

7. CONSTRUCTION OF YAC A YAC is built using an initial circular DNA plasmid, which is typically cut into a linear DNA molecule using restriction enzymes. DNA ligase is then used to ligate a DNA sequence or gene of interest into the linearized DNA, forming a single large, circular piece of DNA.

8. Appropriately modified YACs can be utilized in many different organisms, for cloning or genome analysis. Chromosomal translocation (chromosome abnormality that occurs due to rearrangement of parts among non homologous chromosomes) can be studied by means of disposable YACs that do not contain genetic information necessary for cell function. To identify essential mammalian chromosomal sequences necessary for the future construction of specialized mammalian artificial chromosomes(MACs). APPLICATION OF YAC

9. REFERENCES WEBLIOGRAPHY BIBLIOGRAPHY http://web.ornl.gov/sci/techresources/meetings/bacpac/ http://www.els.net/WileyCDA/ElsArticle/refld-a0000379.html https://www.ncbi.nlm.nih.gov/pubmed/7859160 S.B.Primrose and R.M. Twyman .(2006) Principles of Gene Manipulation and Genomics(7 th ed ), Graphicraft Limited,Hong Kong,p.204-8.