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Biotechnology
Answers
Answer:
01. ans:-
Enzymes should not have more than one site of action. This is because vectors have very few recognition sites for commonly used restriction sites. If it will have more than one restrictrion sites it will generate various fragments. This will, complicates the process of genetic engineering.
2. ans:-
Selection of recombinants due to inactivation of antibiotics is a cumbersome procedure because it requires simultaneous plating on two plates having different antibiotics. ... After the insertion of alien DNA, the recombinant plasmids lose the antibiotic resistance, that is they get inactivated.
3. ans :-
ELISA and PCR serve the purpose of early diagnosis of human diseases
4. ans :-
Proinsulin contains an extra stretch called c peptide. This c peptide is not present in the mature insulin and is removed during maturation into insulin.This is the major difference between them.
5. ans :-
Biopiracy refers to the use of bioresources by multinational companies and other organisations without proper authorisation from people and countries concerned.
OR
The practice of commercial exploitation of biochemicals or genetic materials which occur naturally is known as biopiracy.
6. ans:-
Bt cotton is a genetically modified organism (GMO) or genetically modified pest resistant plant cotton variety, which produces an insecticide to combat bollworm.
The toxin is coded by a gene named cry. There are a number of them, for example the proteins encoded
by the gene cryIAc and cryIIAb control the cotton ballworms that of cryIAb control corn borer.
OR
Herbert Boyer
Herbert Boyer was born in 1936 and brought up in a corner of western
Pennsylvania where railroads and mines were the destiny of most young
men. He completed graduate work at the University of Pittsburgh, in
1963, followed by three years of post-graduate studies at Yale.
In 1966, Boyer took over assistant professorship at the University of
California at San Francisco. By 1969, he performed studies on a couple
of restriction enzymes of the E. coli bacterium with especially useful
properties. Boyer observed that these enzymes have the capability of
cutting DNA strands in a particular fashion, which left what has became
known as ‘sticky ends’ on the strands. These clipped ends made pasting
together pieces of DNA a precise exercise.
This discovery, in turn, led to a rich and rewarding conversation in
Hawaii with a Stanford scientist named Stanley Cohen. Cohen had
been studying small ringlets of DNA called plasmids and which float
about freely in the cytoplasm of certain bacterial cells and replicate
independently from the coding strand of DNA. Cohen had developed
a method of removing these plasmids from the cell and then reinserting
them in other cells. Combining this process with that of DNA splicing
enabled Boyer and Cohen to recombine segments of DNA in desired
configurations and insert the DNA in bacterial cells, which could then
act as manufacturing plants for specific proteins. This breakthrough was
the basis upon which the discipline of biotechnology was founded.
Answer:
1 Ans : It the restriction enzymes have more than one recognition site in a vector, than the vector itself will get fragmented on treatment with the restriction enzyme.
2 Ans : Selection of recombinants due to inactivation of antibiotics is a cumbersome procedure because it requires simultaneous plating on two plates having different antibiotics.
3 Ans : ELISA (Enzyme linked Immuno sorbent Assay) and PCR (Polymerase Chain Reaction) serve the purpose of early diagnosis of human diseases.
4 Ans : Proinsulin contains an extra stretch called c peptide. This c peptide is not present in the mature insulin and is removed during maturation into insulin.This is the major difference between pro-insulin and matured insulin.
5 Ans : The practice of commercial exploitation of biochemicals or genetic materials which occur naturally is known as biopiracy.
6 Ans : Bt cotton is a genetically modified organism or genetically modified pest resistant plant cotton variety, which produces an insecticide to combat bollworm. Cry gene codes for the Bt toxin. Cry I Ac gene and cry II Ab gene control the cotton bollworms and cry I Ab controls corn borer.
OR
Ans. Herbert Wayne Boyer.
(A) He performed studies on a couple of restriction enzymes of the E.coli bacterium with especially useful properties.
(B) He produced synthetic insulin using his new transgenic genetically modified bacteria.
7 Ans :
a. EcoR1 can cut this strand 3 times
b. 7 small pieces of DNA can be formed from this long strand.
c. They are called as sticky-ends” since a DNA molecule with complimentary sequence in the overhang region can anneal to each other.
d. These sticky ends have identical nucleotide sequence and are sticky because they can bind to complementary tails of other DNA fragments cut by the same restriction enzyme. Hence they can be easily ligated by DNA ligase enzymes.
8 Ans :
(a) Selection of recombinants due to inactivation of antibiotics is a laborious process as it requires:-
(i) a vector with two antibiotic resistance marker
(ii) preparation of two kinds of media plate, with one antibiotic each.
Transformed cells are first plated on that antibiotic plate which has not been insertionally inactivated (ampicillin) and incubated overnight for growth of transformants. For selection of recombinants, these transformants are Replica plated on second antibiotic (tetracycline) plate (which got inactivated due to insertion of gene). Non-recombinants grow on both the plates (one carrying ampicillin and the other carrying tetracycline) while recombinants will grow only on ampicillin plate.
This entire exercise is laborious and takes more time (two overnight incubation) as well. However, if we choose the second option (insertional inactivation of a marker that produces colour in the presence of a chromogenic compound), we can distinguish between the recombinants and non-recombinants on a single medium plate (containing one antibiotic and the chromogenic compound) after overnight growth.
Hence I would choose a marker which produces a coloured compound but gets inactivated due to insertion of foreign DNA.
(b) The reasons are as follows :
(i) DNA sample that was loaded on the gel may have got contaminated with nuclease (exo-or endo-or both) and completely degraded.
(ii) Electrodes were put in opposite orientation in the gel assembly that is anode towards the wells (where DNA sample is loaded).
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