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(i) (a) – vector DNA

(b) – foreign DNA

(ii) EcoRI

(iii) DNA ligase

A selectable marker helps to identify transformed host cells and non transformed cells will be eliminated and only transformed cells will grow. Whereas reporter gene is the one whose phenotypic expression can be monitored and thus it reports about activity or change in advance of the effect of modification, in addition to eliminating non transformed cells by selectable markers.

Foam control system, a temperature control system, pH control system and sampling port to take small volume of culture periodically are some other advantages of stirred tank bioreactors.

It is a container in which biochemical process is carried out by using living cells and their growth medium.

Hind II is the first restriction endonuclease.

(i) PCR – Polymerase chain reaction
(ii) – Bacillus thurigenesis.

Responsible for restricting the growth of bacteriophage.

Stanley Cohen and Herbert Boyer were the first to construct a recombinant DNA. They isolated the gene from the bacterium. Salmonella typhimurium.

It is the replacement of a defective gene by normal healthy and functional gene. This method helps to overcome the effect of various disorders like sickle cell anaemia, alkaptonuria, SCID, colour blindness etc.

It is the process of making multiple copies of gene/DNA segments of interest.

(a) PCR :

PCR stands for Polymerase chain reaction. In this reaction multiple copies of the gene (DNA) of interest is synthesized in vitro using two sets of primers (small chemically synthesized oligonucleotides that are complementary to the region of DNA) and the enzyme DNA polymerase. The enzyme extends the primers using the nucleotides provided in the reaction and the genomic DNA as template. Then the process of replication of DNA is repeated many times i.e. one billion copies are made.

(b) Restriction enzyme: 

The enzymes which are responsible for ‘ restricting the growth of bacteriophage in Escherichia coli are called restriction enzymes. One of this enzyme is added to the methyl groups of DNA, while the other cut DNA. This enzyme is known as restriction endonuclease enzyme. The first restriction endonuclease is Hind II. Now more than 900 restriction enzymes have been isolated from over 230 strains of bacteria.

(c) Chitinase:

It is an enzyme obtained from fungus Trichoderma which is specialised to digest chitin of fungal cell walls. The enzyme is used both as an effective fungicide as well as dissolving fungal cell walls to obtain their protoplasts for separation of DNA is genetic engineering.

Downstream processing is the recovery of product from the fully grown genetically modified cells, its purification and preservation.

Because it helps in identifying and selecting the recombinants and eliminating the non recombinants.

Cloning vectors are those organisms on their DNAs which can multiply independently of the host DNA and increase their copy number along with the alien DNA attached to them.

Functions are:

• They help in linking the foreign/alien DNA with that of the host
• They also help in the selection of recombinants from nonrecombinants

“Ori” is a specific sequence of DNA, where replication occurs; the alien DNA must be linked to it, if it has to replicate. The restriction site where a foreign DNA is linked is called “cloning site”.

• Bacteria -Lysozyme
• Fungi – Chitinase

Plasmids and bacteriophages have the ability to replicate within bacterial cells independently of the chromosomal DNA.