1. Cosmid vectors are cloning vectors derived from bacteriophages that can contain up to 44 kilobase pairs of foreign DNA. They are commonly used to clone large fragments of genomic DNA in E. coli. 2. Yeast artificial chromosomes (YACs) are engineered chromosomes used to clone DNA in yeast cells. They contain telomeres, a centromere, autonomous replicating sequences, and selectable markers to replicate and maintain cloned DNA. 3. Plant vectors use the tumor-inducing (Ti) plasmid of Agrobacterium tumefaciens as the primary vector. The Ti plasmid transfers T-DNA containing the gene of interest into the plant genome, allowing genetic modification of

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Vectors
◘ we will taking about 3 Vectors in our lecture : -
1- Cosmid Vector .
2- Yeast artificial chromosome Vector .
3- Plant Vector .
Cosmid Vector
• A cosmid is a type of hybrid plasmid that contains a Lambda
phage cos sequence, (cos sites + plasmid = cosmids)
• Host cell : ( Bacteria ) Prokaryotic (E. coli host )
• DNA sequences are originally from the lambda phage.
• They are often used as a cloning vector in genetic engineering
• Cosmids can contain 44 k bp of DNA.

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• They also contain a gene for selection such as antibiotic resistance, so
that the transformed cells can be identified by plating on a medium
containing the antibiotic. Those cells which did not take up the cosmid
would be unable to grow.
• They Have Multiple cloning site ( poly linker ) , and Origin of
replication .
• Extra-chromosomal circular DNA molecule .
◘ Cloning Steps :-
1- Preparation .
- Target DNA: the genomic DNA to be cloned has to be cut into the
appropriate size range of restriction fragments , By using Restriction
Enzymes , And Cut the Cosmid Cloning site ( poly linker ) by the same
Restriction enzyme , Then Ligation of physically unlinked fragments.
2- Packaging
- the total DNA is transferred into an appropriate E. coli host via a
technique called in vitro packaging (recombinant plasmids contained in
phage shells ) .
- they can also be packaged in phage capsids, which allows the foreign
genes to be transferred into or between cells by transduction (a process
resembling viral infection )

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3- Plating & Growing & Selection & Isolation
- Colonies are formed in selective media , just as with a plasmid vector .
- The media is : Liquid media .
- So that the transformed cells can be identified by plating on a medium
containing the antibiotic ( Ampicillin Agar plate ).
- Those cells which did not take up the cosmid would be unable to grow.
Yeast artificial chromosome Vector
Telomers
AB Resistant Centromere

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- Yeast artificial chromosome (YAC) is a human-engineered
DNA molecule used to clone DNA sequences in yeast cells.
- YAC is an artificially constructed chromosome that contains a
 Centromere :
 Telomeres :
• for maintenance and stabilization and protect ends from degradation
happened by enzymes .
 Autonomous replicating sequence (ARS)
• element required for replication and preservation of YAC
in yeast cells
 ARS elements are thought to act as replication origins
- Artificial chromosome that contains telomers , (center ) origin
of replication , a yeast centromere , and selectable marker (
Antibody resistance ) for identification in yeast cells.
- Host cell : Yeast cell ( Eukaryotic )
◘ A YAC is built using an initial circular plasmid
- typically broken into two linear molecules using restriction
enzymes
 DNA ligase is then used to ligate a sequence or gene of
interest between the two linear molecules
 forming a single large linear piece of DNA

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Plant Vectors
1- Ti – plasmid ( 1ry vector )
2- plant vector ( 2ry vector )

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◘ Ti – Plasmid
 Tumor inducing plasmids (Ti plasmid) are double stranded
circular DNA present in Agrobacterium tumefaciens.
 Agrobacterium is a Gram negative soil bacterium which
infects plants. ( Host cell : plant cell )
 Agrobacterium tumefaciens infects damaged plant tissues,
induces the formation of a plant tumor growth called crown
gall ( grown gall ) .
 Crown gall ( grown gall ) formation occurs when a fragment
of Ti plasmid, referred to as ( T-DNA ) is transferred from
the bacterium in to the host where it gets integrated in to the
plant cell chromosomes.
◘ Plant Vector : -
- The gene of interest integrate with the DNA of the plant ,
produce new traits for the plant using later in Genetic
engineering .

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