Explore topic-wise InterviewSolutions in Current Affairs.

This section includes 7 InterviewSolutions, each offering curated multiple-choice questions to sharpen your Current Affairs knowledge and support exam preparation. Choose a topic below to get started.

1.	How is copy number of the plasmid vector related to yield of recombinant protein?
Answer» The recombinant DNA can multiply as many times as the copy number of the vector plasmid thereby determining the yield of recombinant protein, So, higher the copy number of plasmid vector, higher the copy number of gene and consequently, protein coded by the gene is produced in high amount.

2.	Would you choose an exonuclease, while producing a recombinant DNA molecule?
Answer» No, as exonuclease acts on the free ends of linear DNA molecule, Therefore instead of producing DNA fragments with sticky ends. It will shorten or completely degrade the DNA fragment containing the gen e of interest and the circular plasmid (vector) will not got cut as it lacks free ends.

3.	Both a wire maker and a molecular biologist who had developed a recombinant vaccine claim to be biotechnologists. Who in your opnion is correct?
Answer» In my opnion both of them are correct. As biotechnology is a very wide area which deals with techniques of using a natural organism for its parts as well as genetically modified organism to produce and processes useful for markind. A wine maker employs a strain of yeast to produce wine by fermentation (a nature phenomenon). while the molecular biologist has clonied gene for the antigen (that is used as vaccine) in an organism which allows the production of the antigen in large amount.

4.	Restriction enzymes that are used in the construction of recombinant DNA are endonucleases which cut the DNA at specific recognition sequence? What would be the disadvantage if they do not cut the DNA at specific recogniion sequence?
Answer» If the restriction enzymes would cut DNA at random sites instead of at specific sites, then the DNA f ragments obtained will not h ave sticky ends in the absence of sticky ends. Construction of recombinant DNA molecule would not be possible.

5.	A recombinant DNA molecule was created by ligating a gene to a plasmid vector. By mistake. An exonuclease was added to the tube containing the recombinant DNA. How does this affect the next step in the experiment, i.e., bacterial trasformation?
Answer» The experiment will not likely to be affected as recombinant DNA molecule is circular and closed, with no free ends. Hence, if will not be a substrate for exonclease enzyme which removes, nucleotides from the free ends of DNA.

6.	What modification is done on the Ti-plasmid of Agrobacterium tumefaciens to convert it into cloning vector?
Answer» The plasmid is disarmed by deleting the tumour inducing genes in the plasmid. So, that it become an effective cloning vector. The modified tumour inducing (Ti) plasmid of Agrobacterium tumefacients will no longer remain pathogenic to the plants but still deliver genes of interest into a variety of plants.

7.	An antibiotic resistance gene in a vector usually helps in the selection ofA. competent cellsB. transformed cellsC. recombinant cellsD. None of these
Answer» Selectable markers help in identifying and elminating non-transofrmants selectively permiting the growth of the transformation . The normal E, coli cells do carry resistance against any of these antiobiotics. Completant bacterial cells are no capable to take foreign DNA with chemical treatment, e.g., calcium chloride.

8.	While isolating DNA from bacteria, which of the following enzymes is not used ?A. LysozymeB. RibonucleaseC. DeoxyribonucleaseD. Protease.
Answer» In the process of recombinant DNA technology the first step is isolation of DNA. Since the DNA is enclosed within the membranes, we have to break the cell open to release DNA is enclosed within the membranes, we have to break the cell open to release DNA along with other macromolecules such as RNA, proteins ,polysaccharides and also lipids. this can be achieved by treating the bacterial cells/plant of animal tissue with enzymes such as lysozyme (bacteria), cellulase (plant cells) and chitinase (fungus). As we know that genes are located on long molecuels of DNA interwined with proteins such as histones. the RNA can be removed by treatment with ribonuclease, whereas proteins can be removed by treatment with protease. Other molecuels can be removed by appropriate treatments and purified DNA ultimately precipitates out after the addition of chilled ethanol Deoxyribonclease is not used in tis process as this enzyme causes the lysis of DNA molecuels.

9.	Rising of dough is due isA. multiplication of yeastB. production of `CO_(2)`C. emulsificationD. hydrolysis of wheat flour starch into sugars .
Answer» Correct Answer - B Inoculation of kineaded flour with baker yeast, Saccharomyces cerevislae produce `CO_(2)` during the process of fermentaion, causes puffing up of the dough and make it soft and spongy. It is used to make foods like idii, dosa,bread, etc.

10.	An enzyme catalysing the removal of nucleotides from the ends of DNA isA. endonucleaseB. exonucleaseC. DNA ligaseD. Hind II
Answer» Restriction enzymes belongs to a class of enzymes called nucleases and are of two types (i) Exonucleases remove nucleotides from the ends of the DNA. (ii) Endonucleases make cuts at specific positions within the DNA. DNA ligase is a sealing enzymes (also called as genetic gum), which is responsible for joining of two individual fragments of DNA, whereas Hind II is first discovered restricition endonclease enzyme.

11.	How does one visulaise DNA on an agarose gel?
Answer» A compound called ethidium bromide stains DNA. Which on exposure with ultra-violet (uv) radiation gives orange light band of DNA. Hence. DNA framents appear as orange band in the presence of ethidium bromide and UV light.

12.	In agarose gel electrophoresis, DNA molecules are separated on the basic of theirA. charge onlyB. size onlyC. charge to size ratioD. All of these
Answer» In agarose gel electrophoresis, the DNA fragents separate out (resolve) according to their size of length because of the sleving property of agarose gel. It means, the smaller the fragment size. The farther it will move.

13.	Which of the following is not a source of restriction endonuclease ?A. Haemophilus influenzaeB. Escherichla coliC. Agrobacterium fumelaciensD. Bacilus amyloli
Answer» Agrobacterium tumefecians is a pathogen of several dicot plants it delivers a piece of DNA known as DNA in the plasmid which trasnforms normal plant cells into tumour cells to produce chemicals against pathogens. The restriction enzymes Eco Rl, is isolated from Escherichla coli R Y 13. The first restriction enzymes Hind II was isolated from bacterium Haemophilus influenzae. the resistriction enzyme Bam HI is isolated from Bacl lius amyloli.

14.	Which of the following steps are catalysed by Taq polymerase in a PCR reaction ?A. Denaturation of template DNA.B. Annealing of primeres to template DNAC. Extension of primer end on the template DNAD. All of the above.
Answer» In polymerase chain reaction polymerisation or extension step is catalysed by Taq polymearse enzyme, PCR is carried out in the following three steps (i) Denaturation the double standard DNA is denatured by applying high temperature of `95^(@)C` for 15 seconds Each separated single standard strant now acids as template for DNA synthesis. (ii) Annealing Two sets of primers are added which anneal to the 3 and of each separated strand. primers act as initiators of replication. (iii) DNA polymerase extends the primare by adding nucleotides complementary to the template provided in the reaction. A thermostable DNA polymerase (Taq DNA polymerase) is used in the reaction which can tolerate the high temperature of the reaction. All these steps are repeated many times to obtain several copies of desired DNA.

15.	Which of the following has popularised the PCR (polymerase chain reactions)?A. Easy availability of DNA templateB. Availability of synthetic primeresC. Availability of cheap deoxyribonucleotides.D. Availability of Thermostable DNA polymerase
Answer» The polymerase Chain Reaction (PCR) is a reaction in which amplification of specific DNA sequcne is carried out in vitro. Such repeated amplification is achieved by the use of a thermostable DNA polymerase (Isolated from a bacterium, Themus aquaticus), which remain active and stable during the high temperature and induced denaturation of double standard DNA.

16.	While doing a PCR, denaturation step is missed. What will be its effect on the process?
Answer» If denaturation of double-stranded DNA does not take place then primere will not be able to anneal (joining) to the template. Hence, no extension will take place and after are there will be no amplification.

17.	What would happen when one grows a recombinant bacterium in the bioreactor but forget to add antibiotic to the medium in which the recombinant is growing?
Answer» In the absence of antibiotic there will be no pressure on recomb inants to retain the plasmid (containing the gene of our interest). Sinc e, maintaining a high copy number of plasmids is a metabolic burden to the microbial cells. It will thus tend to loose the plasmid.

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