Introduction of recombinant DNA technology, types of recombinant vectors, bacteriophage, Bacterial vectors, Agrobacterium, PBR 322 ETC. THEIR ROLE, PROPERTIES OF GOOD VECTOR

1. Recombinant
Vectors
Dr. Sonali Randive-Aherkar

3.  Introduction
 Types of vector
 Plasmid
 PBR322
 PUC
 Bacteriophage
 Cosmid

4.  Vectors are isolated from bacteria
 They should be easy for isolation
 They have ability to replicate host DNA with its own.
 It should be easily inserted in to interested plant or
animal.
 It should not affect host DNA
 They have antibiotic resistant, restriction sites.

5.  Bacteria are able to express foreign genes inserted
into plasmids. Plasmids are small, circular, double-
stranded DNA molecules lacking protein coat that
naturally exists in the cytoplasm of many strains of
bacteria.
 Some of the examples of naturally occurring
plasmids are Ti plasmids, F-factors, R-factors,
Co/E1 plasmid.
 range in size from 1000 to 200 000 base pair

6.  pBR322 has a relatively small
 size of 4,363 bp. This is important because
transformation efficiency is inversely proportional to
 size and above 10 kbp is very low.
 ‘p’ indicates as a plasmid
 2. ‘BR’ identifies Bo-liver and Rodriguez, the two
 researchers who developed it.
 3. ‘322’ distinguishes those plasmids from others
(like
 pBR 325, pBR 327, etc.) developed in the same
 laboratory.

8.  pUC are obtained by modifying the pBR322 vector. pUC
vectors are smaller than pBR322
 of being only ~2.7 kb. But comparatively they have a high
copy number. A mutation within the
 origin of replication produces 500 to 600 copies of the
plasmid per cell without amplification.
 ‘p’ indicates the plasmid.
 2. ‘UC’ stands for university of California where it was first
developed by J. Messing et al.
 We also see many numbers after this like pUC8, pUC18,
pUC19 etc.

10.  Bacteriophages, or phages as they are commonly
known, are viruses that specifically infect bacteria.
Like all viruses, phages are very simple in structure,
consisting merely of a DNA (or occasionally
ribonucleic acid (RNA)) molecule carrying a number
of genes, including several for replication of the
phage, surrounded by protective coat or capsid
made up of protein molecules.

12.  Cosmids are the hybrids between the phage DNA
molecule and bacterial plasmid.
 A cosmid is basically a plasmid that carries a cos
site. It also needs a selectable marker.
 such as ampicillin resistant gene, and a plasmid
origin of replication. This is important to note that
 as cosmid lacks all the lambda genes,