(a) Plasmid
(b) Restriction Enzymes
(c) Palindrome sequence
(d) Transposons

Vectors are of two types:
i) Cloning Vector, and ii) Expression Vector.
Cloning vector is used for the cloning of DNA insert inside the suitable host cell. Expression vector is used to express the DNA insert for producing specific protein inside the host.

When microbes are cultured, they secrete some enzymes into the growth media. These enzymes are industrially used in detergents, food processing, brewing and pharmaceuticals.
E.g. Protease, amylase, isomerase, and lipase.

Restriction endonuclease. e.g: Hind II, EcoR I, Pvul, Bam H I, Taq I.

Since the DNA is a hydrophilic molecule, it cannot pass through cell membranes, In order to force bacteria to take up the plasmid, the bacterial cells must first be made competent to take up DNA. This is done by treating them with a specific concentration of a divalent cation such as calcium.

Type II enzyme is preferred for use in recombinant DNA technology as they recognise and cut DNA within a specific sequence typically consisting of 4-8 bp.

A restriction enzyme or restriction endonuclease is an enzyme that cleaves DNA into fragments at or near specific recognition sites within the molecule known as restriction sites.
Types
(i) Exonucleases - which remove nucleotides one at a time from the end of a DNA molecule. e.g. Bal 31, Exonuclease III.
(ii) Endonucleases - which break the internal phosphodiester bonds within a DNA molecule. e.g. Hind II, EcoRI, PvulI, BamHI, TaqI.
(iii) The restriction enzymes are called as molecular scissors
(iv) They are used in recombinant DNA technology as they recognize & cut DNA within a specific sequence.

Agarose Gel Electrophoresis is used mainly for the purification of specific DNA fragments. Agarose is convenient for separating DNA fragments ranging in size from a few hundred to about 20000 base pairs. Polyacrylamide is preferred for the purification of smaller DNA fragments. The gel is complex network of polymeric molecules. DNA molecule is negatively charged molecule - under an electric field DNA molecule migrates through the gel. The electrophoresis is frequently performed with marker DNA fragments of known size which allow accurate size determination of an unknown DNA molecule by interpolation. The advantages of agarose gel electrophoresis are that the DNA bands can be readily detected at high sensitivity. The bands of DNA in the gel are stained with the dye Ethidium Bromide and DNA can be detected as visible fluorescence illuminated in UV light will give orange fluorescence, which can be photographed.

Bioremediation:
It is defined as the use of microorganisms or plants to clean up environmental pollution.
Some examples of bioremediation technologies are :
(i) Phytoremediation - use of plants to bring about remediation of environmental pollutants.
(ii) Mycoremediation - use of fungi to bring about remediation of environmental pollutants.
(iii) Bioventing is the process that increases the oxygen or air flow to accelerate the degradation of environmental pollutants.
(iv) Bioleaching is the use of microorganisms in solution to recover metal pollutants from contaminated sites
(v) Bioaugmentation is the addition of selected microbes to speed up degradation process.
(vi) Composting is the process by which the solid waste is composted by the use of microbes into manure which acts as a nutrient for plant growth.
(vii) Rhizofiltration is the uptake of metals or degradation of organic compounds by rhizosphere microorganisms
(viii) Rhizostimulation is the stimulation of plant growth by the rhizosphere by providing better growth condition or reduction in toxic materials