Introduction of recombinant DNA technology, types of recombinant vectors, bacteriophage, Bacterial vectors, Agrobacterium, PBR 322 ETC. THEIR ROLE, PROPERTIES OF GOOD VECTOR
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.
7.
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.
9.
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.
11.
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,