A cloning vector is a small piece of DNA that can accept foreign DNA fragments for cloning. There are several types of cloning vectors including plasmids, bacteriophages, cosmids, bacterial artificial chromosomes (BACs), yeast artificial chromosomes (YACs), and human artificial chromosomes (HACs). Cosmids combine features of plasmids and bacteriophages, allowing large foreign DNA fragments of up to 42 kb to be delivered into host cells. BACs are artificially synthesized plasmids that can accommodate even larger DNA sequences of 150-350 kb without risks associated with other vectors. The choice of vector depends on factors like size of the foreign DNA and stability.

1. CLONING
VECTOR

2. Objectives
 After the end of the presentation we’ll know -
 What is cloning vector?
 Types of cloning vector
– Plasmid
– Bacteriophage
– Cosmid
– Bacterial Artificial Chromosome (BAC)
– Yeast Artificial Chromosome (BAC)
– Human Artificial Chromosome (HAC)
 What determines choice of vector?

3. Cloning vector
 A cloning vector is a small piece of DNA in which a foreignDNA
fragment can be inserted for cloning purposes.
 Most vectors are genetically engineered.
 There are many types of cloning vectors including:
- plasmids - Bacterial artificial chromosome (BAC)
- phages - Yeast artificial chromosome (YAC)
- cosmids -

4. cosmid
• A cosmid, first described by Collins and Hohn in 1978
• It is formed by joining ends of a linearized plasmid DNA with
cos-site of lambda DNA.
• The cosmid DNA can be packed in a capsid of lambda phage in
vitro to form recombinant phage particles.
• Cosmids have advantages of both plasmids and phage vectors
and they can be delivered to the host by the more efficient
infection procedures rather than by transformation.

5. cosmid contin...
• Cosmid has ;-
 an origin of replication,
selectable markers
 gene cloning sites of
plasmid DNA.
• size up to 42 kb of
DNA.
• Examples: Col EI
cosmid, pHC 79, pJB8,
pWE cosmid,

6. Bacterial artificial chromosome (BAC)
 It is artificially synthesized plasmid
 These are similar to E.coli plasmids vectors.
 It is obtained from modification F’plasmid.
 They can accommodate large DNA sequences withoutany
risk.
 size is 150-350 kb.

7. • Contain the
origin and
genes encoding
the ori binding
proteins.
 chloramphenic
ol resistant
gene and
lactose
metabolizing
gene (LacZ)

9. Advantages of BACs compared to
YACs
• Stable
• Ease to transformation
• Speed of growth of E. coli host
• Simpler to purify
• More user friendly
• They are helpful in the development of
vaccines