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Multiple choice question for engineering

Set 1

1. RNaseH method and homopolymer tailing method generates blunt ended cDNA molecules. Which of the following can be used for attaching them to vector?
a) Blunt ended ligation
b) Addition of linkers
c) Using appropriate restriction enzymes
d) All the methods can be used equivalently

View Answer

Answer: d [Reason:] As the products of RNaseH method and homopolymer tailing method generates dsDNA and blunt ended molecules, there are many methods to attach them to vector. Blunt ended ligation, addition of linkers and restriction enzymes all can be used.

2. Choose the correct statement for modification of homopolymer tailing method.
a) It includes modification of primers
b) Primers are varied by simply altering their size by randomly adding or removing bases
c) The 5’ end of the first cDNA strand is tailed with C residues
d) A single stranded oilgonucleotide is then used for second strand synthesis

View Answer

Answer: a [Reason:] The modification of homopolymer tailing method includes modification of primers. Primers can be modified by introduction of restriction sites in them. The 3’ end of first cDNA strand is tailed with C residues. Another oligo-dG primer precedes the introduced restriction site and is contained with the double stranded oligonucleotide region. It is used for second strand synthesis.

3. By synthesizing two strands separately then annealing them leads to formation of double stranded oligonucleotide. Is the given statement true or false?
a) True
b) False

View Answer

Answer: a [Reason:] Double stranded oligonucleotides are required for the synthesis of second cDNA strand. This double stranded oligonucleotide is synthesized by separately synthesizing two strands and then annealing them.

4. Choose the incorrect statement for the homopolymer tailing of cDNA strands.
a) The blunt ended double stranded cDNA molecules are treated with terminal transferase and dCTPs
b) Vector is also treated with terminal transferase and dGTPs
c) The vector and cDNA can now anneal with the help of DNA ligase
d) If gaps are created they can be repaired by physiological processes

View Answer

Answer: c [Reason:] For homopolymer tailing of cDNA strands, the blunt ended double stranded molecules are treated with terminal transferase and dCTPs. This leads to addition of C residues at 3’ end. Vector is also treated with terminal transferase and dGTPs. This leads to annealing of vector and cDNA molecules and DNA ligase is not required. The gaps created can be repaired by physiological processes once the recombinant molecules enter the host.

5. Choose the correct statement if the RNA is non polydenylated.
a) A collection of chemically synthesized oligonucleotides is used as primers
b) They are usually tetramer
c) Unequal quantities of A, G, T and C are used
d) The primers attach at only specific sequences for first strand synthesis

View Answer

Answer: a [Reason:] As the RNA is non polyadenylated, oilgo-dT primer can’t be used and in place of it a collection of chemically synthesized oligonucleotides is used as primers. They are usually hexamers and are made by equal quantities of A, G, C and T. And thus all hexameric sequences can be synthesized. The primers can attach to the RNA sequences throughout.

6. In case if molecules smaller than the fragments required for making a full genomic library, are used for making a collection. This collection is called as:
a) library
b) shelf
c) small library
d) mini library

View Answer

Answer: b [Reason:] If the molecules smaller than the fragments required for making a full genomic library are used for collection, this collection is called as shelf. It is a subsection of library.

7. Choose the correct statement for construction of a library subsection.
a) The size of a particular restriction fragment on which the gene is located is not known
b) The size of the restriction fragment can be known by carrying out southern blotting
c) Another digest of the genomic DNA is carried out by different enzyme
d) DNA fragments of different size are recovered after carrying out gel electrophoresis

View Answer

Answer: b [Reason:] For the construction of a subsection of library, some steps are followed. The size of a particular restriction fragment on which gene is located is known at times. The size of the fragment can be known by carrying out southern blotting. After the size is known, another digest of the genomic DNA is carried out and is done by the same enzyme. DNA fragments of approximately same size are recovered from the gel after carrying out gel electrophoresis. They can be further cloned into a vector.

8. Any cDNA library would represent a fraction of RNA species of an organism. Is the given statement true or false?
a) True
b) False

View Answer

Answer: a [Reason:] Any cDNA library would represent a fraction of RNA species of an organism, the whole organism can’t be represented in a library. It depends on the developmental stage, physiological state and the tissue from which RNA was isolated.

9. What do we mean by housekeeping genes?
a) Housekeeping genes are those genes which are specific to an organism
b) Housekeeping genes are those genes which are present in all the organisms
c) Housekeeping genes are those genes which are meant for repair and maintenance in a species of organism
d) Housekeeping genes are those genes which required for replication process

View Answer

Answer: b [Reason:] Housekeeping genes are those genes which are present in all the organisms. cDNA libraries may therefore contain housekeeping genes and genes specific to that organism.

10. Choose the correct statement for RNA fractionation.
a) The RNA is fractioned by size but before separating on oligo-dT cellulose
b) A sucrose density gradient is used
c) The RNA is applied to the top of a pre-poured gradient and during centrifugation smaller molecules move down the tube faster
d) Different bands are formed according to the density in the sucrose density gradient

View Answer

Answer: b [Reason:] RNA fractionation is carried out and the basis is size. It is fractioned by size after carrying out separation on oligo-dT cellulose. A sucrose density is used for size based separation. The RNA is applied to the top of a pre-poured gradient and during centrifugation larger molecules move down the tube faster. There are different bands formed on the basis of size in the sucrose density gradient.

11. What is done after RNA fractionation is carried out?
a) Each band is translated in vivo
b) Translation is carried out in wheat gram or lysate of rabbit reticulocyte cells
c) Translation is carried out with a high background
d) Amino acid is not radioactively labelled

View Answer

Answer: b [Reason:] RNA fractionation is carried out and it is followed by translation of each band in vitro. It is carried out in wheat gram or lysate of rabbit reticuloycte cells. Ribosomes, tRNAs are added in order to carry out the translation with low background. An amino acid is radioactively labelled and thus the polypeptide sequence synthesized is labelled.

12. The polypeptides produced after addition of mRNA are analysed with antibodies. Choose the incorrect statement for this analysis.
a) Antibodies are added to each reaction tube and precipitation is simply based on antigen-antibody reaction
b) Along with simple antigen-antibody complex, a substrate is added for easy precipitation
c) Protein A-Sepharose is added
d) Protein A-Sepharose binds to IgG antibodies

View Answer

Answer: a [Reason:] The analysis of polypeptides after addition of mRNA can be carried out by addition of antibodies. But it is not simply based on antigen-antibody reaction. A substrate for easy precipitation is also added. For this, protein A-Sepharose is added. Protein A-sepharose binds to IgG antibodies. After carrying out centrifugation, it can be pelleted easily.

13. What is done after the recovery of pellets has been carried out in order to know the amount of polypeptides?
a) Denaturing and gel electrophoresis in SDS- Polyacryamide gel
b) Gel electrophoresis in agarose gel
c) Quantitative PCR
d) Weighing pellets

View Answer

Answer: a [Reason:] After the recovery of pellets has been carried out by the use of antigen- antibody reaction, denaturation and gel electrophoresis in SDS-Polyacrylamide gel. The amount of radioactivity gives the amount and location of polypeptides.

Set 2

1. Insertion vectors are a type of vectors. Choose the correct statement for this type of vector.
a) These are complex vectors
b) DNA is inserted through many restriction sites
c) There is an upper limit on the size of the DNA to be packaged
d) Lambda gt09 is an example of this type of vector

View Answer

Answer: c [Reason:] Insertion vectors are the simple vectors and DNA is inserted through a single restriction site. It must be a non-essential gene to maintain phage viability. There is an upper limit on the size of the DNA to be packaged thus only a few kilobases of the extra DNA can be included. Lambda gt10 and gt11 are an example of insertion vectors.

2. Choose the correct statement for lambda gt10.
a) It is having an EcoRI site
b) It is having cII gene
c) It accepts an insert of size greater than that of 8 kbp
d) This size is less than that the size which is generally accepted by wild type phage

View Answer

Answer: a [Reason:] Lambda gt10 is having an EcoRI site which contains the cI repressor gene. It accepts an insert of size upto 7.6 kbp which is generally more than that of the size generally accepted by a wild type phage.

3. The presence of insert leads to inactivation of which gene?
a) cII
b) cI
c) cIII
d) Both cII and cIII

View Answer

Answer: b [Reason:] The presence of insert leads to inactivation of cI gene and this is the method to detect the presence of an insert.

4. A portion of phage is removed and in place of it the DNA of interest is inserted. This type of vector is called as:
a) displacement vector
b) insertion vector
c) substitution vector
d) transposition vector

View Answer

Answer: c [Reason:] If a portion of phage is removed and in its place the DNA of interest is inserted, it is called as substitution or replacement vector.

5. Choose the incorrect statement for the central portion of lambda genome.
a) The central portion is not required for lytic growth
b) The central portion includes repressor gene
c) The repressor gene is not required for lysogenic growth
d) It is approximately 10kbp long

View Answer

Answer: d [Reason:] The central portion of lambda genome is approximately 20 kbp and it is not required for lytic growth. The central portion constitutes of repressor gene and thus it has to be removed for the lysogenic growth to take place.

6. The fragment inserted in the place of the central portion of genome is known as:
a) insertion fragment
b) substitution fragment
c) stuffer fragment
d) displacement fragment

View Answer

Answer: c [Reason:] The fragment inserted in the place of the central portion of genome is known as stuffer fragment. It is generated by doing partial digestion an enzyme having a 4bp long recognition site.

7. Choose incorrect statement for the substitution vector EMBL4.
a) It is having two single multiple cloning sites
b) The region to be removed is on one side of the multiple cloning sites
c) If a digestion within the multiple cloning sites, it generates central portion and right and left arms
d) The right and left portions are called as arms

View Answer

Answer: b [Reason:] The substitution vector EMBL4 contains two multiple cloning sites. The two multiple cloning sites flank the region which is to be removed. If digestion is done within the multiple cloning sites, it generates central portion and the right and left portions. The right and left portions separated are known as arms.

8. Is it necessary to stop the relegation of central portion before the stiffer fragment is ligated. The given statement is true or false?
a) True
b) False

View Answer

Answer: a [Reason:] The central portion should be stopped from religating before the stuffer fragment should be ligated. There are chances that central portion gets religated to the arms.

9. At times, a second enzyme is used while the central portion is removed and the stuffer fragment is placed there. Choose the statement which doesn’t holds for this process.
a) It is a method which is used for avoiding the relegation of central portion before the stuffer fragment is attached over there
b) In this method, the central portion is cut with another enzyme after being separated from the arms
c) The arms are also cut with this second enzyme
d) It is not necessary to remove the fragments generated

View Answer

Answer: c [Reason:] A second enzyme is used in order to avoid the relegation of central portion and the arms. In this method, the central portion is cut with a second enzyme after being separated from the arms. These arms are not cut with the second enzymes. Hence the ends created are different now and the arms won’t ligate to the central portion again. It is not necessary to remove the fragments generated because the chances of having a multimolecular reaction which are required for the formation of original phage are very less.

10. Physical separation is also used at times. Choose the correct statement in respect to this method.
a) Physical separation constitutes of gel electrophoresis and or by using centrifugation in sugar density gradient
b) In sugar density gradient, the molecules are separated on the basis of density
c) The central portion is recovered from the gel or the gradient
d) Gel is more efficient than the sugar density gradient

View Answer

Answer: a [Reason:] Physical separation is also used at times, it constitutes of using gel electrophoresis or by using centrifugation in the sugar density gradient. In sugar density gradient, the separation is done on the basis of size. The arms are separated from the gel or gradient. Gradient is more efficient than gel, thus gradient is more preferred over gel.

11. Packaging in vitro is also carried out to introduce the lambda DNA into the cells. Choose the incorrect statement in respect to it.
a) Packaging in phage coat is a more efficient process than the normal transformation process
b) The lambda DNA is incubated with lysate of lambda infected cells in a concatemeric configuration
c) Lysate constitutes of lambda proteins needed for phage assembly
d) The amount of non-recombinant phage in the background is less

View Answer

Answer: d [Reason:] Packaging in vitro is used to introduce the lambda. It is more efficient than the normal transformation procedure. Thus, the lambda DNA is incubated with lysate of lambda infected cells in a concatemeric configuration. This lysate constitutes of lambda proteins needed for phage assembly and hence the recombinant DNA is also packed. But there is also a large amount of non-recombinant packaging in the background.

12. Packaging in vitro is basically carried out by two different strategies. Choose the incorrect statement for it.
a) Separate strains with chain-termination mutations in different genes for coat components is used
b) Temperature sensitive cI repressor is used
c) Due to heat shock packaging proteins are induced
d) Packaging is carried out in each strain

View Answer

Answer: d [Reason:] Packaging in vitro is basically out by two different strategies. In the first strategy, separate strains with chain-termination mutations in different genes (mostly D and E genes) for coat components are used. Temperature sensitive cI repressor is used and due to induction by heat shock, packaging proteins are produced. But packaging is not carried out in any of the strain because none of the strain is having full complement of proteins to carry out packaging.

13. Chain-termination mutations in coat proteins genes are carried out. The coat protein coat genes used are:
a) A gene
b) D gene
c) E and D gene
d) D and A gene

View Answer

Answer: c [Reason:] Chain-termination mutations in coat proteins genes are carried out, these genes are D and E genes.

Set 3

1. Plasmids are used for carrying out the cloning procedure. Which of the statement is true for plasmids?
a) Bacterial plasmids are linear in nature
b) They are single stranded
c) Insertion of DNA into plasmid allows it to be propagated in host cells and they are known as vectors because of their this property
d) They are not capable of replication in bacteria

View Answer

Answer: c [Reason:] Plasmids are double stranded and they are circular in nature. They are capable of replication in bacteria. Insertion of DNA into plasmid allows it to be propagated in host cells and the molecules which are used for propagation by this method are called as vectors.

2. Which of the following characteristic is not present in a plasmid on a general basis?
a) Multiple cloning site (MCS)
b) Origin of replication (ori)
c) Antibiotic resistance gene
d) Beta galactose genes

View Answer

Answer: d [Reason:] Plasmid generally consists of characteristics such as multiple cloning site, origin of replication, antibiotic resistant genes and beta galactosidase genes. An origin of replication is necessary for the replication to take place.

3. bla is a gene, which is incorrect for it?
a) It is an antibiotic resistance genes
b) Antibiotic acts by blocking the cross-linking of the bacterial cell wall and thus leading to lysing of cells
c) It encodes beta lactamase enzyme
d) The beta lactam ring is activated

View Answer

Answer: d [Reason:] bla is an ampicillin resistant gene. Antibiotic acts by blocking the cross-linking in the bacterial cell wall and thus leading to lysing of the cells. If antibiotic resistant gene is used, which encodes for beta lactamase enzyme it inactivates the beta lactam gene by hydrolysing it.

4. Which of the characteristics is present in lacZ gene?
a) It encodes for beta galactosidase enzyme
b) Beta galactosidase enzyme is responsible for cleaving monosaccharides into the constituent elements
c) It doesn’t cleaves a substrate called as X-gal
d) But if X-gal is cleaved, it liberates pink coloured dye

View Answer

Answer: a [Reason:] lacZ gene encodes for beta galactosidase enzyme. This enzyme is responsible for cleaving of disaccharides into monosaccharides. It cleaves a substrate known as X-gal, which then liberates a blue dye.

5. Which of the following orientation is not propagated to later stages?
a) Circular plasmids having genomic DNA
b) Intramolecular ligation of plasmids
c) Linear molecules
d) Head to head ligation of two DNA plasmids

View Answer

Answer: c [Reason:] When a cloning experiment is carried out, there various orientations which are possible. The orientation which is not propagated to the later stages is linear molecule. Other possible orientations are relegation of plasmid, intramolecular ligation of genomic DNA. Intermolecular ligation of two DNA plasmids and genomic plasmids is also possible.

6. Molecules having new combination of sequences that were not present before are called as:
a) intermolecular ligants
b) recombinants
c) couple
d) intramolecular ligants

View Answer

Answer: b [Reason:] After cloning experiment is carried out, there are various orientations possible. Molecules having combination of new sequences which were not present earlier are called as recombinants.

7. Insertion of DNA into lacZ gene may lead to disruption of the gene function. This given statement is true or false?
a) True
b) False

View Answer

Answer: a [Reason:] Insertion of DNA into lacZ gene may lead to disruption of the gene function. It always doesn’t so but there are minimal chances that function is not disrupted because often it leads to shifting of the reading frame.

8. Transformation efficiency is defined as:
a) ratio of transformed colonies by microgram of sample DNA that is to be inserted
b) ratio of transformed colonies by amount of sample DNA that is to be inserted
c) ratio of transformed colonies by microgram of plasmid DNA
d) ratio of transformed colonies by amount of plasmid DNA

View Answer

Answer: d [Reason:] Transformation efficiency is defined as the ratio of transformed colonies to that of the amount of plasmid DNA which is taken. It is often altered by altering the competence of the cells.

9. After carrying out the cloning experiment, the cells are plated on agar. Along with agar, it also contains antibiotic resistant genes, X-gal and an inducer of lacZ gene. Which of the following would grow?
a) Cells that have taken up plasmid DNA
b) Cells that have taken up genomic DNA
c) Cells having no insert
d) Cells either having no insert or having genomic DNA

View Answer

Answer: a [Reason:] Only cells that have taken up the plasmid DNA would be able to grow. It is so because only plasmid is having antibiotic resistant genes and the rest will die after few generations.

Set 4

1. The ________ protein of bacteriophage P1 mediates site-specific recombination at a 34 bp sequence, loxP.
a) cre recombinase
b) gene II
c) gene IV
d) gene VIII

View Answer

Answer: a [Reason:] The Cre recombinase protein of bacteriophage P1 mediates site-specific recombination at a 34 bp sequence, loxP.

2. Choose the incorrect statement for cre-lox excision.
a) The chromosomal copy of the target gene replaces the target gene flanked by loxP sites
b) The second step is supply of Cre recombinase
c) Integration of cre takes place under a controllable promoter followed by induction of the promoter
d) Induction results in expression of cre, recombination along loxP sites and excision of the sequence between

View Answer

Answer: a [Reason:] For cre-lox excision, the chromosomal copy of the target gene is replaced by target gene flanked by loxP sites. The second step is supply of cre recombinase. Integration of cre is done by a controllable promoter which is followed by the induction of promoter. This induction results in expression of cre and recombination along loxP sites, leading to excision.

3. Cre can be introduced by crossing it with a strain containing the gene or by infection with virus containing it. Is the given statement true or false?
a) True
b) False

View Answer

Answer: a [Reason:] Generally cre is introduced with the help of a promoter. But it can also be introduced by crossing it with a strain containing the gene or by infection with virus containing it.

4. How much effect is there on the surrounding genes by the loxP sequence which is left after recombination has take place?
a) Little effect
b) No effect
c) Huge effect
d) It depends on the nature of the surrounding gene

View Answer

Answer: b [Reason:] As the recombination has taken place, the loxP sequence remains there. The remaining loxP sequence has no effect on the surrounding genes.

5. The ability to control the expression of cre allows controlling what?
a) recombination
b) replication
c) excision
d) packaging

View Answer

Answer: c [Reason:] The ability to control the expression of cre allows when and where excision takes place. Specific excision of the target takes place if expression is tissue or time specific.

6. Excision of DNA flanked by loxP sequences is also known as _________
a) subtle excision
b) croxing
c) floxing
d) sequence specific excision

View Answer

Answer: c [Reason:] Excision of DNA flanked by loxP sequences is called as floxing at times. Other site specific recombination systems are also used.

7. RNA molecule with catalytic activity is termed as________
a) ribosomes
b) catalytic RNA
c) reactive RNA
d) ribozyme

View Answer

Answer: d [Reason:] Any RNA molecule with catalytic activity is termed as ribozyme. Some of the catalytic activity can be removal of introns by self-splicing.

8. Hepatitis delta virus capable of self cleavage. Is the given statement true or false?
a) True
b) False

View Answer

Answer: a [Reason:] Hepatitis delta virus, which is associated with hepatitis B is capable of self cleavage. Ribozymes mainly comprise of RNA molecules which are capable of self cleavage.

9. Choose the correct statement for self cleavage reaction.
a) It is nucleophilic attack reaction by 2’ hydroxyl of RNA
b) It is nucleophilic attack reaction by 3’ hydroxyl of RNA
c) It is nucleophilic attack reaction by 2’ hydroxyl of DNA
d) It is nucleophilic attack reaction by 3’ hydroxyl of DNA

View Answer

Answer: a [Reason:] In the self cleavage reaction, it is an internal nucleophilic attack reaction by 2’ hydroxyl of RNA. The attack is done on the phosphate group in the sugar phosphate group.

10. Self cleavage reaction can take place in?
a) DNA
b) RNA
c) Both DNA and RNA
d) Can take place in both but is preferred in DNA

View Answer

Answer: b [Reason:] The self cleavage reaction takes place in RNA. It is because it involves nucleophilic attack by 2’ hydroxyl, which is found in RNA and not in DNA.

Set 5

1. Lesch-Nyhan syndrome is caused by deficiency of the enzyme hypoxanthine-guanine phosphoribosyl transferase (HGPRT). Cells deficient in HGPRT die in a medium containing which of the following?
a) Hypoxanthine and thymidine
b) Thymidine
c) Aminopterin and thymidine
d) Hypoxanthine, thymidine and aminopterin (HAT medium)

View Answer

Answer: d [Reason:] HGPRT deficient cells in the medium containing all three hypoxanthine, thymidine and aminopterin. It is so because aminopterin blocks endogenous synthesis of purines needed for synthesis of nucleic acid.

2. Presence of wild-type DNA onto the HGPRT– in the presence of _______ led to DNA uptake and stable transformation.
a) lithium acetate
b) calcium phosphate
c) sodium chloride
d) aluminum sulphate

View Answer

Answer: b [Reason:] Presence of wild type in HGPRT—in the presence of calcium phosphate led to DNA uptake and stable transformation.

3. Cells deficient in thymidine kinase (TK) are also killed in HAT medium. Is the given statement true or false?
a) True
b) False

View Answer

Answer: a [Reason:] Cells deficient in thymidine kinase are also killed in HAT medium. It is so because pyrimidine synthesis is also blocked in the presence of aminopterin and utilization of thymidine in the HAT medium requires a functional TK.

4. Hygromycin is used as a selectable marker in mammalian cultured cells. It is used for:
a) initiating protein synthesis
b) inhibiting protein synthesis
c) initiating DNA binding process
d) inhibiting DNA binding process

View Answer

Answer: b [Reason:] Hygromycin is used as a protein synthesis inhibitor. It is conferred by a bacterial hph gene which encodes hygromycin phosphotransferase. Resistance to hygromycin is used as a selectable marker.

5. Puromycin, is a protein synthesis inhibitor. It is conferred by_______ gene:
a) streptococcal
b) bacilovirus
c) streptomyces
d) both streptococcal and streptomyces

View Answer

Answer: c [Reason:] Puromycin is a protein synthesis inhibitor and is conferred by streptomyces gene. It does so by encoding puromycin-N-acetyltransferase.

6. Resistance to bleomycin (zeocin) is used as a selectable marker for mammalian cultured cells and its function is:
a) DNA damaging agent
b) DNA synthesis promoter
c) Inhibiting RNA synthesis
d) Activating RNA synthesis

View Answer

Answer: a [Reason:] Resistance to bleomycin (zeocin) is used as a selectable marker for mammalian cultured cells and it is a DNA damaging agent. It does so by expression of a binding protein.

7. Resistance to methotrexate, which inhibits the enzyme dihydrofolate reductase (DHFR) is used as selectable marker. This enzyme is involved in synthesis of _____ carbon units and is required for _____ biosynthesis.
a) two, nucleoside
b) two, nucleotide
c) one, nucleotide
d) one, nucleoside

View Answer

Answer: d [Reason:] Resistance to methotrexate, which is used as a selectable marker inhibits DHFR enzyme. This enzyme is involved in synthesis of one carbon units and is required for nucleoside synthesis.

8. Histidinol dehydrogenase allows synthesis of histidine from exogenous histanol. Is the given statement true or false?
a) True
b) False

View Answer

Answer: a [Reason:] Histidinol dehydrogenase is also used as a selectable marker. It allows synthesis of histdidine from exogenous histanol and protects from toxic effects of histidinol.

9. Many mammalian cells contain Thymidine Kinase, the mammalian enzyme uses the analogue _____ than does the viral enzyme.
a) more efficiently
b) less efficiently
c) with same efficiency
d) either with same or more efficiency

View Answer

Answer: b [Reason:] Many mammalian cells contain thymidine kinase, the mammalian enzyme uses the analogue less efficiently than the viral enzyme. If cells lack viral enzyme they are resistant to analogue and are able to grow in mammalian enzyme.

10. A wide range of host cell lines are available and commonly used human cell lines are obtained from:
a) kidney
b) liver
c) lymphoblast from leukaemia patient
d) both kidney and lymphoblast from a leukaemia patient

View Answer

Answer: d [Reason:] There is a wide range of host cell lines available. Commonly used human cell lines are HeLa 293T, obtained from kidney and Jurkat which is obtained from lymphoblast from a leukaemia patient.

11. DEAE-dextran is used for introduction of DNA. It is a modified _____ and is ______
a) polysaccharide, negatively
b) polysaccharide, positively
c) monosaccharide, positively
d) monosaccharide, negatively

View Answer

Answer: b [Reason:] There are various methods for uptake of transformation DNA such as electroporation and DEAE-dextran method. It is a modified polysaccharide and is positively charged. It forms a complex with negatively charged DNA and is taken into cells by endocytosis.

12. Cells whose contents have been removed and replaced, by swelling and shrinking in solutions of suitable osmotic strength are called as:
a) protoplast
b) ghosts
c) shrunken cells
d) vacuole

View Answer

Answer: b [Reason:] Ghosts are those cells whose contents have been removed and replaced by swelling and shrinking in solutions of suitable osmotic strength. Red blood ghosts are also used for introduction of DNA into mammalian cells.

13. In _____ cells, virus replication doesn’t take place and viral DNA _____
a) non-permissive, is also not expressed
b) permissive, is also not expressed
c) non-permissive, can be expressed
d) non-permissive, is always expressed

View Answer

Answer: c [Reason:] In non-permissive cells, virus replication doesn’t take place and viral DNA can be expressed though.

14. SV40 is a virus and it produces how many transcripts?
a) 1
b) 2
c) 3
d) 4

View Answer

Answer: b [Reason:] SV40 is a virus and it produces two transcripts. These transcripts are produced by early and late transcripts.

15. Splicing of the transcripts is necessary for efficient expression. Is the given statement true or false?
a) True
b) False

View Answer

Answer: a [Reason:] Splicing of both the transcripts is necessary and it is for efficient expression. Sequences that have not been through splicing process are not expressed efficiently even if introns are removed.