Explore topic-wise InterviewSolutions in .

(1) Scientific value of transgenic animals:

• Transgenic mice are used medical research to identify the functions of specific factors through over – or under-expression of a modified gene (the inserted transgene). They are designed to study how genes contribute to the development of disease. These animals are used to investigate development of diseases like cancer, cystic fibrosis, rheumatoid arthritis, etc. 
• In toxicology field, they are used for detection of toxicants. They are used as responsive test animals.

(2) Commercial value of transgenic animals:

Transgenic cattle are used for production of human therapeutic proteins such as human lactoferin, human serum albumin, etc. 

Better quality and quantity of wool by transgenic sheep.

cys E, cys M

Correct answer is (b) product patent

Texmati is a trade name of “Basmati rice line and grains” for which Texas based American company Rice Tec Inc was awarded a patent by the US Patent and Trademark Office (USPTO) in 1997.

First biopatent was awarded for genetically engineered bacterium ‘Pseudomonas’ used for clearing oils spills.

Duration of biopatents is five years from the date of the grant or seven years from the date of filing the patent application, whichever is less.

Correct answer is (d) All of these

Correct answer is (b) Bacillus thuringiensis

Recombinant DNA is the DNA formed by combining DNAs from two different organisms.

A plasmid is a circular extra-chromosomal DNA molecule present in a bacterial cell, which replicates autonomously, of the bacterial chromosomal DNA.

Agarose the name of the substance used as a medium/matrix in gel electrophoresis.

The instrument for bombarding micro-projectile particles (gold/tungsten particles) coated with foreign DNA, with great velocity, into a target cell is called gene gun.

Electrophoresis was developed by Tiselius in 1937 and is based on the principle that charged particles move under the influence of electric current to oppositely charged electrodes.

Ethidium bromide.

Gel electrophoresis.

i. cDNA—Complementary DNA

ii. Bt—Bacillus thuringiensis

Centrifugation and centrifuge

E. coli and Saccharomyces cerevisiae.

a.

Positive terminal – ‘B’

Negative terminal – ‘A’

b. DNA is negatively charged. Because of its negative charge, DNA moves towards the positive electrode (anode).

c. The separated DNA fragments are separated by elution. The separated bands of DNA are cut out from the agarose gel and extracted from the gel piece.

Normal Endonuclease makes cuts at random positions within a DNA sequence. Restriction endonuclease makes cuts only at specific positions within a DNA sequence.

a. ori: Ori is a sequence from where replication starts and any piece of DNA when linked to this sequence can be made to replicate within the host cells. It is also responsible for controlling the copy number of the linked DNA.

b. amp^R: The ligation of alien DNA is carried out at a restriction site present in any antibiotic resistance gene.

c. rop: It codes for the proteins involved in the replication of the plasmid.

Ethidium bromide (EtBr) exchanges its visible range of wavelength with the invisible wavelength of DNA to make it visible under UV light.

CHO is a eukaryotic host cell so it is used to clone eukaryotic gene. 

(i) dNTP & ddNTP

dNTP used in DNA replication

ddNTP used in chain termination

Structural differences can also be shown

(ii) pBR322 & pUC19

pBR322 - contains two antibiotic resistant genes

pUC19 - contains MCS

(iii) M-13 & lambda phage

M-13 : Circular and single stranded Lambda 

phage : Linear double stranded 

(iv) Cosmid & plasmid

Cosmid : having features of plasmid and cos sites of phage lambda 

Plasmid : small, circular, extra-chromosomal self replicating naturally present in bacteria

(v) Transformation and transfection 

Transformation: Cold CaCl2 treated competent bacterial cells to introduce rDNA 

Transfection: Transfer rDNA into host cells by mixing foreign DNA with charged substances like calcium liposomes/calcium phosphate/DEAE dextran 

In pUC19 –two bands

Linear DNA 

Because restriction endonuclease cleaves the DNA internally

The negatively charged oxygen anion is able to make a nucleophilic attack on the carbonyl carbon of the peptide bond of its substrate. 

It loosens the carbonyl carbon, so that a water molecule can hydrolyse the bond. 

Recombinant DNA technology involves the following steps:

i. Isolation of DNA

ii. Fragmentation of DNA by restriction endonucleases.

iii. Isolation of a desired DNA fragment.

iv. Amplification of the gene of interest.

v. Ligation of the DNA fragment into a vector.

vi. Insertion of recombinant DNA into the host.

vii. Culturing the host cells on a suitable medium at a large scale.

viii. Extraction of the desired gene product.

ix. Downstream processing of the products as finished product, ready for marketing.

If denaturation of double-stranded DNA does not take place, then primers will not be able to anneal to the template, no extension will take place, hence no amplification will occur.

DNA being hydrophilic in nature cannot pass through the cell membranes into the host. Therefore, cloning vectors are required to transfer the DNA into the host by attaching the desired DNA to it.

The two cloning vectors that are used are plasmids and bacteriophages.

The two strands of ds tDNA will not be separated if denaturation step is missed. These would be no annealing of primers to the template and therefore no extension of DNA would occur.