3. COMMON GENE COMPONENTS IN BAC
RepE: for plasmid replication and regulation of copy
ParA and parB: for partitioning F plasmid DNA to daughter
cells during division and ensures stable maintenance of the
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
OriS: the origin of replication
5. 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
6. 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
Many different YAC plasmids exist, such as pYAC3 & pYAC4.
7. COMPONENTS OF YAC
The vector contains several elements of typical yeast
CEN: A yeast centromere, that ensures chromosome
partitioning between two daughter cells and a selective
ARSI: Yeast autonomously replicating sequence
TEL: Yeast telomere
Yeast selectable marker such as URA3 & TRP1 and
Bacterial selectable marker.
8. CONSTRUCTION OF YAC
A YAC is built using an initial circular DNA plasmid, which is
typically cut into a linear DNA molecule using restriction
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.
10. 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