Telomere and Its enzyme
The chromosomal end consists of hairpin structure synthesized by an enzyme called Telomerase reverse transcriptase. And the structure is called Telomere which is repetitive sequence of nucleotide.
Cell Communication
The living cells of an organism communicate with one another, either by direct contact between cells or by means of chemical signals.
Mutation and its types
Stable genetic alterations occurs due to change in the nucleotide sequence of a genome in an organism, that usually, but not always leads to change in phenotype.
Industrial use of Microorganism
Industrial Microorganisms deals mainly with their major category i.e Food, Pharmaceuticals and Bioremediation. Microorganims are genetically modified inorder to increase their efficiency for better yield.
18 October 2013
PI3K Pathway
13 September 2013
Phage Vector
Ultraviolet Mutagenesis
Purines and pyrimidine absorbs UV at 260 nm wavelength, which makes a perfect source for identifying nucleic acids in Electrophoresis.
11 September 2013
Cloning Vector : Vehicle for transport foreign DNA into Host cell.
Ti plasmid as vector for plants
- It is circular and not always
- It’s contains 56%GC content out of which 81% encodes for a protein.
- It has various types of opines
- Octopine
- Nopaline
- Succinamopine
- Leucinopine
- It is found in Agrobacterium tumefacien and Agrobacterium rhizogenes.
- There is no pseudogene.
- It works only in dicotyledon plants.
- The Ti plasmid is lost when Agrobacterium is grown above 28°C. Such cured bacteria do not induce crown galls, i.e. they become avirulent.
- virA codes for a receptor which reacts to the presence of phenolic compounds such as acetosyringone, syringealdehyde oracetovanillone which leak out of damaged plant tissues.
- virB encodes proteins which produce a pore/pilus-like structure.
- virC binds the overdrive sequence.
- virD1 and virD2 produce endonucleases which target the direct repeat borders of the T-DNA segment, beginning with the right border.
- virG activates vir-gene expression after binding to a consensus sequence, once it has been phosphorylated by virA.
Plasmid
- F plasmid à Involves in conjugation for transferring information to another bacteria.
* It contains genes responsible for cell attachment and plasmid transfer between specific bacterial strains during conjugation.
* It has an insertion sequences that assist plasmid integration into the host cell chromosome.
(Small Picture of F plasmid.)
- R plasmid à resistance to antibiotic.
- Degradative plasmid à carry specific genes for the utilization of unusual metabolites.
- Cryptic plasmid à no functional coding genes.
- Col plasmids à colicin production. Bacteriocin gene produces cloacins which kills bacteriophages.
4) High copy number plasmids (relaxed plasmids) à 10-100 copies of plasmids per host cell.
5) Low copy number plasmids (Stringent plasmids) à 1-4 copies of plasmids per host cell.
6) Host range of plasmid is determined by its ori region. And there are two host range of plasmid i.e. Restricted where the plasmid is restricted to replicate in certain bacteria only (eg: Plasmid Col E1 replicates only in enteric bacteria like E.Coli or salmonella) and Broad host range where the plasmid can replicate any group of bacterium (RP4 plasmid can replicate in most of gram negative bacteria).
Plasmids look like a coiled rubber band and . Topoisomerase, an enzyme that regulates the winding (over or under) of the DNA. It relaxes the supercoiled plasmid and brings CCC form. But if a Endonuclease (Enzyme cleaving the phosphodiester bond of DNA) attacks this uncoiled CCC, then a nick is formed in one of the strands of plasmid DNA. So therefore it forms a open circular DNA. The nick can be cured by another enzyme called DNA ligase which joins both the ends of the DNA strand. This enzyme is one of the important enzyme for joining the fragmented DNA with the plasmid.
Now, DNA gyrase is type of Topoisomerase II which provide negative supercoiling of DNA by cutting the double strands and then joining them together by twisting the ends.
In certain bacteria like streptomyces sp or Borrelia burgdorferi, plasmids are found in linear form. To protect the ends from nuclease digestion, there are two general mechanism involved:
a) terminal contains a hairpin loop structure (Borrelia).
b) terminal are protected by covalent attachment of protein (Streptomyces sp.)
1. It contains 4,361 bp and
carries two antibiotic resistance genes: Ampr (Ampicillin) and Tetr
(Tetracycline).
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cDNA Library - A detailed note
Genomic Library- A detailed note
8 September 2013
Endocytosis: Import system of the cell
- Phagocytosis
- Pinocytosis
- Receptor Mediated Endocytosis