- A bioreactor is a vessel in which raw materials are
biologically converted into specific products by microbes,
plant and animal cells and their enzymes. These are used
for food processing, fermentation, waste treatment, etc.
Growth conditions that a bioreactor provides for obtaining
the desired products are as follows:
(i) Controlled environment for optimum product yield.
(ii) Aseptic fermentation for number of days and
prevention of escape of viable cells.
(iii) Adequate mixing and aeration for optimum growth
and production, without damaging the microorganism.
(iv) Easy and dependable temperature control.
(v) Facility of sampling.
- Differences between type I, type II and type III restriction
endonucleases are as follows:
Type I Type II Type III
(i) Enzyme structure
consists of three
different subunits.
Enzyme
structure is
simple.
Enzyme structure
consists of two
different subunits.
(ii) They require ATP, Mg2+
and S-adenosyl-
methionine for
restriction.
They require
Mg2+ for
restriction.
They require ATP,
Mg2+ and
S-adenosyl
methionine for
restriction.
(iii) They recognise
specific sites
within the DNA
but do not cut
these sites.
They
recognise
specific sites
within the
DNA and cut
these sites.
They recognise
specific sites
within the DNA
but do not cut
these sites.
(iv) They are not used
in recombinant
DNA technology.
They are used
in recombinant
DNA
technology.
They are not used
in recombinant
DNA technology.
- (a) Bacillus thuringiensis produces Bt toxin, an insecticidal
protein. This protein kills insects such as lepidopterans
(tobacco budworm, armyworm), coleopterans (beetles)
and dipterans (flies, mosquitoes), but it does not kill
the Bacillus (bacterium) itself.
(b) cry gene codes for this toxin. The toxin does not kill the
bacterium Bacillus, as it exists in the form of inactive
protoxins. However, once an insect ingests the inactive
toxin, it is converted into an active form of toxin, due to
the alkaline pH of the gut, which then creates pores in
the midgut epithelial cells and cause cell swelling, lysis
and finally death of the insect.
(c) Proteins encoded by genes cry IAc and cry IIAb control
the cotton bollworms, while cry IIAb controls corn
borers.
- Biological products are useful in treating certain human
diseases. They are often very expensive. These expensive
biological products can be produced in good quantity in
transgenic animals by inserting genes for these products
into them. Usually milch animals are used for this purpose
so that the biological product is available in their milk and
from which the same can be extracted and purified. This
process is called molecular farming or molecular harvesting.
The important biological products being harvested by
this method are proteins a – 1 antitrypsin for treating
emphysema, tissue plasminogen activator (goat) etc.
- Gel electrophoresis is done to separate and isolate DNA
fragments. The procedure is as follows :
(i) DNA is cut into fragments by restriction endonucleases.
(ii) DNA fragments separate according to their size or
charge.
(iii) DNA fragments being negatively charged, are
separated by forcing them to move through matrix
under an electric field.
(iv) Agarose, a natural polymer obtained from sea weeds is
used as the matrix.
(v) The separated molecules are stained by ethidium
bromide and visualised by exposure to UV radiation, as
bright orange coloured bands.
(vi) The separated bands of DNA are cut from the agarose
gel and extracted from the gel piece by elution.
- (a) When bioresources of one country are exploited or
patented by some multinational companies or organisations
of other countries without proper authorisation from
concerned country and compensation is referred to as
biopiracy.
(b) To prevent unauthorised exploitation of bio-resources
and traditional knowledge, the Indian Parliament has
recently cleared the second amendment of the Indian
Patents Bill, that takes biopiracy issues into consideration,
including patent terms, emergency provisions, research and
development initiatives.
- The basic requirements of a polymerase chain reaction are:
(i) DNA template – The desired segment of target DNA
molecule that is to be amplified.
(ii) Primers – Two nucleotide primers, usually 10-18
nucleotides long and complementary to the sequences
present at the 3′ end of the target DNA segment.
(iii) Enzyme – Ta q DNA polymerase which is stable at high
temperature is required to carry out synthesis of new
DNA.
OR
Agrobacterium tumefaciens is a soil-inhabiting bacterium
that may invade growing plants at the junction of root and
