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Multiple choice question for engineering

Set 1

1. Which one of the following is not done if amplification of the non flanking region is carried out?
a) Firstly, restriction enzyme digestion is done of those sites whose sequence is not known
b) Then the self-ligation of molecules is allowed
c) Now the molecules are cleaved where the known sequence is
d) Again, the molecules are linearized and the known sequence is in the middle

View Answer

Answer: d [Reason:] If such amplification has to be carried out, firstly the restriction enzyme digestion is done at those sites whose sequence is not known till now. Then self ligation is carried out i.e. conditions for intramolecular ligation is applied. As the molecules circularize now, cleavage is carried out of known sequence. As the known sequence is cleaved, the molecule is now cleaved with known sequence at the ends. As it known sequence, primers can be constructed for it and the unknown region is amplified.

2. Reverse transciptase PCR is also carried out at times. Which of the statement is true?
a) Amplification of RNA samples is not required for knowing the abundance of mRNA
b) Both the start and the end primers are used
c) Only a single cDNA strand is synthesized before the PCR
d) The primer used is always specific

View Answer

Answer: d [Reason:] Reverse transciptase PCR is carried out by the use of reverse transciptase enzyme. RNA amplification is necessary at times to know the abundance of mRNA. In this only one primer is used and one cDNA strand is synthesized before the PCR. The primer can be oligo-dT for general cDNA synthesis or a specific primer is used.

3. Which type of PCR allows the use of permeabilized tissue?
a) Inverse PCR
b) In-situ PCR
c) Quantitative PCR
d) Hot-start PCR

View Answer

Answer: b [Reason:] In-situ PCR allows the use of permeabilized tissue, such as thin sections on a microscopic slide. The PCR product is detected by hybridization and it allows locating the nucleic acid in the target tissue.

4. How many approaches are there for measuring the quantity of PCR products?
a) 1
b) 2
c) 3
d) 4

View Answer

Answer: b [Reason:] There are basically two approaches for measuring the amount of PCR products. These are known as end-point approach and real time approach. In end-time approach the amount is measured once the PCR is done. In real time approach the amount is measured while the PCR reaction is still going on.

5. Which of the statement hold true for Quantitative PCR?
a) A fluorescent dye is used which binds on single stranded DNA molecules
b) SYBR green is an example such type of dye
c) The quantity of DNA is simply measured by measuring the amount of fluorescence
d) This approach is useful if the products are non-specific in nature

View Answer

Answer: c [Reason:] A fluorescent dye is used which binds on double stranded DNA molecules and SYBR green is an example of such type of dye. The quantity of DNA is measured by simply measuring the amount of fluorescence. It is used only in the case if products are created specifically because it simply relies on binding of dye to double stranded molecules.

6. In another method of quantitative PCR, reporter-quencher set up is used. Which of the statement holds true for this methodology?
a) It allows detection of all double stranded molecules
b) The reporter and quencher are the molecules present on the same probe
c) The quencher is having a fluorescent group
d) Fluorescence is observed only when both the groups are present in proximity to each other

View Answer

Answer: b [Reason:] This method allows the detection of only specific molecules. It is so because the probes are specific for areas to be amplified. The probe consists of reporter at one end and quencher at the other. The reporter consists of the fluorescent group which fluoresce only when the quencher is released. Quencher is released as specific binding of probe is taking place.

7. By using two oligonucleotides, we can measure the amount of quantity of DNA by measuring the amount of fluorescence. The first probe absorbs light and the second emits it at particular wavelength. Is the mentioned phenomenon true or false?
a) True
b) False

View Answer

Answer: a [Reason:] If two oilgonucleotides are used, which bind nearby to the target DNA help in quantifying the DNA. The first probe is meant for absorbing light and the second probe absorbs the light emitted by the first one and then re-emits it. DNA is quantified by measuring the fluorescence from second probe and it is possible only when both the probes are close to each other i.e. they have bound to the location near the target DNA.

8. Choose the correct statement with regard to quantitative PCR?
a) End-point PCR is favourable over real time PCR
b) In real time PCR, quantification is done as the reaction is going on
c) If the product measurement is done after the completion then the measurement is done by target sequence and no other factor affects it
d) If the primers are available in limited amount, then the product obtained is proportional to the target sequence

View Answer

Answer: b [Reason:] Real-time PCR is favourable over end-point PCR. It is so because real-time PCR is performed when the PCR is going on and the end-point PCR is performed when the PCR has been completed. In the end-point PCR, it is limited by the amount of reactants such as primers. If fewer amounts of primers are there, the product formed is less and is not proportional to the amount of target sequence only.

9. Mutation is never deliberately induced in PCR products. The given statement is true or false?
a) True
b) False

View Answer

Answer: b [Reason:] Mutation is deliberately induced in PCR product at times and the process is termed as mutagenesis. In mutagenesis, primers are constructed in such a way that they correspond to the mutated sequence rather than the original one.

10. If amplification of one of the strand is favoured, the modification of PCR is known as:
a) single-strand PCR
b) partial PCR
c) asymmetric PCR
d) anchored PCR

View Answer

Answer: c [Reason:] If amplification of one of the strand is preferred, it is called as asymmetric PCR. This leads to the formation of single stranded products which are having uses such as in sequencing.

11. Which of the statement is incorrect for anchored PCR?
a) Anchored PCR is the modification in which only one piece of sequence is known and thus one primer
b) The known sequence is attached to the required region of amplification and then further used as second priming site
c) Fragment the sample DNA and ligate it to known sequence
d) Tails are added enzymatically to the region of known sequence

View Answer

Answer: d [Reason:] Anchored PCR is based on the fact that only a piece of sequence is known and thus only one primer. The known sequence is attached to the required region of amplification and is further used as second priming site. The sample DNA is fragmented and ligated to known sequence. Also, enzymatically tails are added to the sample DNA or to the molecules formed after first round of synthesis. This tail can be further used as a primer.

12. Emulsion or droplet PCR is another modification of PCR. Which of the statement holds true?
a) It is possible to incorporate the reagents in a lipid drop
b) It refers to the PCR carried out at large scale
c) The temperature variation is not possible easily
d) If there is a single template molecule at the start then amplification results in mixture and it because of the extent of extension carried out

View Answer

Answer: a [Reason:] It is possible to incorporate the reagents in a lipid drop. In this type, PCR is carried out at small scale. The temperature of these drops can be varied easily. If there is a single template in the DNA molecule then the amplification results in only one type of molecules.

13. Isothermal amplification is carried out at times. Which of the statement is true?
a) The repeated heating and cooling required by PCR is not the reason for limiting how quickly the reaction is carried out
b) It is carried out typically at 65 degrees
c) Normal Taq polymerase is used
d) It requires expensive PCR machines to be carried out

View Answer

Answer: b [Reason:] Isothermal PCR is that in which the reaction is carried out at typically 65 degrees. The repeated heating and cooling cycles required by the PCR is the reason for limiting how quickly the reaction is carried out. In this case DNA polymerase with strand displacing activity is used and it avoids heating at high temperatures. It is a rapid process and expensive PCR machines are not used.

Set 2

1. What happens if chain-termination mutation is in the S gene?
a) Cell lysis is blocked
b) Growth of cells containing low levels of packaging proteins is not allowed
c) The lysis of cells is not carried artificially
d) Packaging is not carried out efficiently

View Answer

Answer: a [Reason:] If chain-termination mutation is carried out is in the S gene, cell lysis is blocked. The growth of cells having high levels of packaging proteins is carried out. The lysis is then carried out artificially.

2. Which of the following is used for blocking the phage-encoded recombination?
a) Mutation in D gene
b) Mutation in E gene
c) Red mutation
d) Mutation in S gene

View Answer

Answer: c [Reason:] Red mutation is used for blocking the phage-encoded recombination. It ensures that no recombination or rearrangement takes place while carrying out packaging in vitro.

3. Which of the following is not a consequence of deletion in the b region?
a) Excision of the prophage on induction is prevented
b) It reduces the amount of endogenous phage DNA in the packaging mix
c) It reduces the amount of exogenous phage DNA in the packaging mix
d) It reduces the level of background non-recombinant phage

View Answer

Answer: c [Reason:] The deletion in b region is responsible for preventing the excision of the prophage on induction. It reduces the amount of endogenous phage DNA in the packaging mix and thus resultantly it reduces the level of background non-recombinant phage.

4. If a single system is used for packaging, there are increased chances of endogenous material being packed. The given statement is true or false.
a) True
b) False

View Answer

Answer: a [Reason:] In the case if a single strain is used for packaging, there are increased chances of endogenous material being packed. It can be avoided by using additional mutations such xis in the prophage to stop the excision and packaging of the lysogenic phage from the cells producing packaging extract.

5. The cI function can be scanned in order to check whether the recombinants are present or not. Which of the following doesn’t hold true?
a) The cI protein is required for the formation of lysogen
b) The plaques formed are turbid in the case if cI gene is active
c) The plaques formed are clear in the case if cI gene is inactive
d) hflA mutant host reduces the amount of cII stability

View Answer

Answer: d [Reason:] The cI protein is required for the formation of lysogen to take place. The plaques formed are clear in the case if cI is inactive and turbid in the case if cI is active. hflA (high frequency of lysogenization) mutant hosts is used for enhanced screening. It is so because, it increases the amount of cII stability and thus consequently lysogenization is taking place efficiently.

6. What is the function of red and gam gene products?
a) It promotes the growth of the phage in the E. coli cells which are lysogenic for bacteriophage P1
b) It inhibits the growth of the phage in the E. coli cells which are lysogenic for bacteriophage P2
c) It inhibits the growth of the phage in the E. coli cells which are lytic for bacteriophage P1
d) It activates the growth of the phage in the E. coli cells which are lytic for bacteriophage P2

View Answer

Answer: b [Reason:] The red and gam gene products inhibit the growth of the phage in the E.coli cells which are lysogenic for bacteriophage P2. When red and gam gene products are absent, the growth takes place in the cells which are lysogenic to bacteriophage P2.

7. The red and gam genes are removed in which type of phages?
a) Substitution phage
b) Replacement and substitution phages both
c) Replacement phage
d) Substitution is preferred over replacement phage

View Answer

Answer: c [Reason:] The red and gam genes are removed in replacement vectors. And this can be used as a potent method to select the recombinants by plating them on P2 lysogen.

8. Phages which are designated as spi- are:
a) red+ gam+
b) red+ gam-
c) red- gam+
d) red- gam-

View Answer

Answer: d [Reason:] red- gam- are called as spi- and they are not able to grow on P2 lysogens. The red+ gam+ mutanats are called as spi+.

9. Choose the correct statement for RecBCD nuclease.
a) It promotes rolling circle replication
b) It is blocked by Gam protein
c) It blocks theta mode of replication
d) It is blocked by Red protein

View Answer

Answer: b [Reason:] RecBCD nuclease is blocked by Gam protein and it blocks rolling circle replication. As the rolling circle mode is blocked, replication would be carried out by only theta mode of replication.

10. The essential sites for recombination are known as:
a) chi sites
b) rec sites
c) gam sites
d) red sites

View Answer

Answer: a [Reason:] The sites necessary for recombination are known as chi sites. Host recombination enzymes may not work until and unless the recombination sites are present.

11. The replication rate remains same for all the phages irrespective of what sequence is there in the phage. Is the given statement true or false?
a) True
b) False

View Answer

Answer: b [Reason:] The replication rate is not same for all the phages. Some phages having a certain insert may be replicating in a slower rate than that of other phages. Thus, there might be underrepresentation of some of the sequences.

12. There is a limit on upper size of the DNA to be packed. Choose the correct statement with respect to phages in this context.
a) There is some phage DNA lost in this process
b) The phages are known as transformed phages
c) These type of phages can’t be selected and harvested
d) Lambda is not a special attachment site

View Answer

Answer: a [Reason:] There is a limit on upper size of the DNA to be packed. If the significant amount of sequence is flanked by the phage particles, there are chances of losing some phage DNA. These phages are known as transducing phages and can be easily selected and harvested for the lost DNA. Lambda is having a special site for attachment in E. coli.

13. There are some phages which don’t preferentially transduce some special regions of phage genome. These phages are known as:
a) transducing phages
b) specialized transducing phages
c) generalized transducing phages
d) transforming phages

View Answer

Answer: c [Reason:] Some phages are there which don’t preferentially transduce some special regions of phage genome and they are known as generalized transducing phages.

Set 3

1. The process of baking or cross-linking of membrane is carried out by:
a) By heating at 80 degrees
b) By irradiating with UV
c) Both irradiation and heating method are used
d) By addition of agarose

View Answer

Answer: c [Reason:] The cross-linking or baking of membrane is carried out by either heating it at 80 degrees or irradiating with UV. It is important to carry out this step because it binds the DNA irreversibly to the membrane.

2. Choose the incorrect statement for prehybridization mixture.
a) The function of it is to carry out specific binding
b) It constitutes of non-labelled DNA of non-specific sequence which is obtained from salmon or herring testes or sperm
c) It is added in small amount
d) It is carried out before the hybridization is carried out

View Answer

Answer: a [Reason:] Prehybridization mixture is meant for blocking sites which are meant for non-specific binding. It constitutes of non-labelled DNA of non-specific sequence which is obtained from salmon or herring testes or sperm. They are added in small amount and it is added before the hybridization is carried out. So that when hybridization is carried out, only specific binding takes place.

3. After hybridization how the position of the labelled DNA probe is determined?
a) By staining
b) By UV irradiation
c) By using chemiluminescence
d) By electronic microscope

View Answer

Answer: c [Reason:] After the hybridization has been carried out and the membrane has been washed, the position of the labelled DNA probe is determined by using chemiluminescence. Commonly the probe is labelled by incorporation of fluoroscein conjugated molecules.

4. The important parameters for precise annealing of the probe and the subsequent washing don’t include:
a) Size of the probe
b) Proportion of only A
c) Ionic concentration of hybridization buffer
d) Other agents which alter the base pairing

View Answer

Answer: b [Reason:] The probe should anneal precisely and the parameters which decide these are size of the probe, proportion of all A, G, T and C. Ionic concentration of hybridization buffer and other agents such as formamide which alter base pairing. These parameters define the maximum temperature at which probe and target DNA bind fully.

5. If hybridization is carried out with a clone having a sequence similar to that of the vector from which library has been constructed, then it is of no use. Choose the correct statement in respect to it.
a) PCR amplification of the probe can be carried out
b) Excision of the probe should be carried out which should be followed polyacrylamide gel electrophoresis
c) If the vector sequence and the DNA probe are having similarities, some of the vector would be hybridized
d) Probe should be in a vector that is having some sequence similarity with the library to be screened

View Answer

Answer: a [Reason:] If hybridization is carried out with a clone having a sequence similar to that of the vector from which the library has been constructed then all the vector would hybridize. To make the sequence different, PCR amplification of the probe can be carried out. Also, excision of the probe can be carried out by using suitable restriction enzymes and it is followed by agarose gel electrophoresis. Or probe in a vector should not have any sequence similarity with the library to be screened.

6. At what temperatures the hybridization and washing of the DNA probes should be carried out?
a) At melting temperature
b) At a temperature lower than the melting temperature
c) At a temperature higher than the melting temperature
d) At 100 degrees

View Answer

Answer: b [Reason:] The hybridization and washing of the DNA probes should be carried out at temperature below than the melting temperature. It is so because if it is carried out a temperature lower than the melting temperature, some amount of mismatch is allowed. Melting temperature depends on the composition of the probes.

7. Which library should be used, genomic or cDNA when the screening is carried out by oligonucleotide probes?
a) Genomic
b) cDNA
c) Both genomic and cDNA library can be used equivalently
d) None of the libraries are preferred if oligonucleotide probes are used

View Answer

Answer: b [Reason:] If oligonucleotide probes are used, then cDNA libraries should be used. It is so because cDNA libraries are enriched for coding sequences and thus fewer sequences have to be screened.

8. Sometimes successive rounds of screening of a genomic library are carried out and an ordered collection of clones is done in a linear fashion, then the process is called as:
a) chromosome jumping
b) chromosome sorting
c) chromosome walking
d) transposon tagging

View Answer

Answer: c [Reason:] Chromosome walking is the process of successive rounds of screening of a genomic library and it leads to collection of clones in a linear order.

9. If the clone for a gene is obtained on the basis of its position in the gene map, then it is called as:
a) locational cloning
b) positional cloning
c) chromosome walking
d) transposon tagging

View Answer

Answer: b [Reason:] If the clone for a gene is obtained on the basis of its position in the gene map then it is called as positional cloning.

10. Mobile portions of a chromosome which can be transferred from one portion to another are termed as:
a) mobile part
b) transposons
c) walking elements
d) transferrable genetic element

View Answer

Answer: b [Reason:] Transposons are the mobile portions of the chromosomes which can be transferred from one portion of the chromosome to another either on the same chromosome or different chromosome.

Set 4

1. Sometimes the required mRNA is present in less number. So the process of increasing the representation of rare mRNAs is called as:
a) amplification
b) normalization
c) selection
d) narrowing

View Answer

Answer: b [Reason:] If the required mRNA is present in less number, its representation can be increased by a process called as normalization. It reduces the number of times the library has to be screened for required cDNA.

2. Choose the correct statement in order to enrich rare species.
a) The most basic principle relies on kinetics of hybridization
b) A collection of single stranded molecules is allowed to reanneal under given conditions
c) The strands which are less abundant are able to find their complement easily
d) The left over molecules are more abundant in nature

View Answer

Answer: a [Reason:] In order to enrich the rare species, the basic principle relies on the kinetics of hybridisation. A collection of double stranded cDNA molecules is allowed to melt. As the strands melt away, they are then allowed to reanneal under suitable conditions. The more abundant the species is, the more easily they anneal. The rare species are obtained in single stranded form because it is difficult to reanneal them.

3. Which statement holds true for hydroxyapatite?
a) It binds to single stranded molecules more tightly than double stranded molecules
b) It binds to linear molecules more tightly than circular molecules
c) It binds to circular molecules more tightly than linear molecules
d) It binds to double stranded molecules more tightly than single stranded molecules

View Answer

Answer: d [Reason:] Hydroxyapatite is the molecule which binds more tightly to the double stranded molecules than the single stranded molecules. This property is very useful in the process of enrichment of rare species.

4. Libraries in which a particular sequence is present in one organism but are absent from another organism, are called as:
a) normalized libraries
b) subtractive libraries
c) selective libraries
d) partial libraries

View Answer

Answer: b [Reason:] Sometimes it happens that a particular sequence is present in one organism but is absent from another organism, such libraries are known as subtractive libraries.

5. The nucleic acid from the cell type that contains the sequence we are interested in is called as:
a) driver
b) subtractive sequence
c) tracer
d) wanted sequence

View Answer

Answer: c [Reason:] The nucleic acid from the cell type containing the sequence we are interested in is called as tracer. The driver is the molecule which lacks the sequence.

6. Choose the correct statement for libraries constructed by mixing cell types differing in the sequences they are having.
a) The driver and tracer are mixed in double stranded form
b) Tracer is in stoichiometric excess in comparison to driver
c) Tracer and driver are in same amount
d) The sequences are allowed to hybridize

View Answer

Answer: d [Reason:] It is about subtractive libraries. The driver and tracer are mixed in single stranded form and driver is in stoichiometric excess in comparison to driver. It is about tenfold excess. The sequences are mixed and allowed to hybridize.

7. Which of the following is desirable?
a) Driver- driver hybrid
b) Driver- tracer hybrid
c) Tracer- tracer hybrid
d) Driver alone

View Answer

Answer: c [Reason:] Our sequence of interest is present in tracer. So if it hybridizes with driver, it means that the sequence is present is it also and thus it is not required by us. Hence, either tracer-tracer hybrids or single stranded tracers are required.

8. Which of the statement holds true?
a) The tracer is treated with enzyme which generates compatible ends
b) The driver is treated with enzyme which generates compatible ends
c) Both driver and tracer are treated with enzyme to generate compatible ends
d) Both driver and tracer are treated with enzyme to generate incompatible ends

View Answer

Answer: a [Reason:] The tracer is treated with enzyme which generates compatible ends and the driver is treated to generate incompatible ends. It is done so because then driver-driver or driver-tracer hybrids won’t form. Only tracer-tracer hybrids would form.

9. If physical methods are used, tracer is amplified and is labelled with biotin. Is the given statement true or false?
a) True
b) False

View Answer

Answer: b [Reason:] In the case of physical removal methods, the driver is amplified and is labelled with biotin. After hybridization between tracer and driver, streptavidin is added and it attaches to biotin. Methods such as phenol extraction are used in order to remove streptavidin and sequences attached to it. Thus, tracer sequences which are not attached to driver remain in the aqueous phase only.

10. Sometimes a gene which we want to clone is present on a particular chromosome. For this purpose, the chromosome should be in which phase?
a) Prophase
b) Telophase
c) Metaphase
d) Anaphase

View Answer

Answer: c [Reason:] The chromosomes should be in metaphase state because then they will be in condensed form and it would be easy to handle them.

11. For cloning purposes, the intact chromosomes should be separated by:
a) agarose gel electrophoresis
b) fluorescence- activated sorter
c) polyacrylamide gel electrophoresis
d) chromatography

View Answer

Answer: b [Reason:] For cloning purposes, the intact chromosomes should be separated by using fluorescence-activated sorter. The amount of fluorescence obtained is based on the amount of dye and thus depends on the size of the chromosome.

12. The process of examining stained chromosomes in a light microscope and removing appropriate regions with a micro-manipulator is called as:
a) microdissection
b) chromosome sorting
c) chromosome walking
d) chromosome jumping

View Answer

Answer: a [Reason:] The process of separating the region of interest from a chromosome is termed as microdissection. It is carried out by firstly staining the chromosome and then observing it under a light microscope.

Set 5

1. What is the size of the DNA molecule which can be packed by the viral protein coat?
a) 100kbp
b) 200kbp
c) 500kbp
d) No size restriction

View Answer

Answer: d [Reason:] There is no size restriction on the DNA molecule which is packaged by the viral coat protein. It is an advantage.

2. The uniform layer of cells is known as lawn and the holes peppered from infected cells are termed as:
a) plaques
b) holes
c) colony
d) pothole

View Answer

Answer: a [Reason:] The infected cells, which are from the infection by bacteriophage create holes and they are termed as plaques.

3. M13 doesn’t actually lyse the cells. Is the given statement true or false?
a) True
b) False

View Answer

Answer: a [Reason:] M13 doesn’t actually lyse the cells. It infects the cells and retards the growth but doent actually lyse the cells.

4. The plaques formed by M13 infection are called as:
a) retarded plaques
b) true plaques
c) pseudoplaques
d) lysogenized plaques

View Answer

Answer: c [Reason:] As the plaques created by M13 are because of slow growth and not because of lysis, these plaques are called as pseudoplaques.

5. M13 vector is tightly packed. Where is the available site to insert DNA>
a) In the gene II
b) Between gene II and IV
c) Between gene III and V
d) Between gene V and VIII

View Answer

Answer: b [Reason:] The production of phage depends upon the insertion of DNA without disrupting any of the phage genes. Hence, M13 vector is tightly packed. One such site for the insertion of DNA is between gene II and gene IV. Here, the lacZ and MCS are also present.

6. Choose the incorrect statement with respect to collection of single stranded molecules.
a) An infected culture is set up and after a while the cells are removed by centrifugation
b) The phage is in the supernatant and is precipitated by addition of glycol and sodium chloride
c) The phage pellet is resuspended and phenol is used for removal of protein
d) The single stranded molecules sediment at the bottom

View Answer

Answer: d [Reason:] The collection of single stranded molecules is slightly different. An infected culture is set up and after a while cells are removed by centrifugation. The phage is present in the supernatant and is precipitated by addition of glycol and sodium chloride. It is followed by centrifugation. The phage pellet is resuspended and phenol is used for removal of protein. The single stranded molecules remain in the solution and thus can be precipitated further.

7. Choose the correct statement for Sanger’s method of sequencing.
a) They are also called as chain termination methods
b) Use of M13 vector is made for getting double stranded DNA
c) Use of dideoxynucleotide phosphate (ddNTP) is made
d) The use of M13 vectors is more preferred these days

View Answer

Answer: a [Reason:] Sanger’s method of DNA sequencing is also known as chain termination method of sequencing. Dideoxynucleoside triphospahte (ddNTP) are used as chain terminating agents. M13 vector is used to obtain the single stranded DNA. Now days there are technologies available for sequencing on double stranded DNA, thus it reduces the use of M13 vectors these days.

8. Which of the statement doesn’t holds for phage display systems?
a) The filamentous phage is often used as phage display system
b) Coding sequences are inserted in one of the protein coating genes
c) The most common protein coding genes are gene II or gene VIII
d) The inserted is expressed along with other protein coat genes

View Answer

Answer: c [Reason:] The filamentous phage is often used as phage display system. The coding sequences are inserted in one of the protein coding genes and the most common protein coding genes are gene III and gene VIII. The insert is expressed along with other protein coat genes.

9. Choose the correct statement for synthesis of RNA probe?
a) Double stranded DNA is only used for probe synthesis
b) Single stranded DNA can be used for probe synthesis
c) Probes are prepared for RNA transcripts which are specific for only particular strand
d) Probes are prepared for RNA transcripts which are specific for both the strands

View Answer

Answer: b [Reason:] RNA probe can be synthesized by single stranded DNA. This single stranded DNA can be obtained from filamentous phage. Probes are prepared for RNA transcripts which are specific for either of the DNA strands.

10. M13-plasmid vectors are often used. Which of the following is not a feature for this?
a) They are known as phagemid, plage or phasmid
b) Replication takes place through the origin of replication of M13 derivatives only
c) Replication from M13 requires proteins to be provided by helper phage
d) Some of the examples of these types of combination are pUC 118, 119 and 120

View Answer

Answer: b [Reason:] M13-plasmid vector hybridization is often used and they are referred to as phagemid, phasmid or plage. Replication can take place either by the origin of replication of the plasmid or by the origin of replication of M13. Replication from M13 requires additional protein to be provided from helper phage. Single- stranded DNA is produced after replication and is packaged in a protein coat. Some of the examples of this type of hybridization are pUC 118, 119 and 120.

11. The main advantage of phagemid is that it can be used for generation of single or double stranded products without recloning. The given statement is true or false?
a) True
b) False

View Answer

Answer: a [Reason:] The main advantage of pahgemid is that it can be used for generation of single or double stranded products without recloning. It is so because M13 can be used to produce single stranded products and the double stranded products are obtained by using origin of replication of plasmid.