Multiple choice question for engineering
Set 1
1. Introduction of DNA molecules into the recipient organism is termed as:
a) transformation
b) translation
c) transduction
d) transcription
Answer
Answer: a [Reason:] Introduction of DNA molecules into the recipient organism is termed as transformation. It is done with the help of endonucleases and ligases and the recipient organism is termed as host.
2. Many bacterial species are having a natural ability to take up the exogenous DNA material. Which of the statement is not correct in regard to it?
a) This ability is termed as competence
b) It is not limited to particular growth phases
c) The bacteria may develop new biochemical abilities under special conditions such as nutrient deprivation
d) Induction of specific set of bacterial proteins may take place
Answer
Answer: b [Reason:] This ability is termed as competence and it is limited to particular growth phases. It may lead to developing new biochemical abilities under special conditions such as nutrient deprivation. If the bacterial cells are naturally competent, they may take the foreign DNA by simply incubating them with foreign DNA.
3. Which of the statements hold true for conjugation?
a) Conjugation is the natural process of transferring DNA from one species to another
b) It is the artificial process in case the cells are not able to take them up naturally
c) The plasmids are transferred from one cell to another by physical contact
d) The plasmids are transferred from one cell to another by chemical means
Answer
Answer: b [Reason:] Conjugation is the process used for transferring plasmids from one cell to another in case they are not able to take up naturally. It is done via physical contact and the plasmid being transferred encodes the machinery.
4. F plasmid is often used in conjugation. The correct statement is?
a) The F plasmid encodes the factor which is transferred from one cell to another
b) The factor encoded by the F plasmid is called as Filamentous (F) factor
c) It is transferred from one cell to another by filament
d) The bacteria must belong to same species to carry out the conjugation
Answer
Answer: a [Reason:] F plasmid encodes the factor called as Fertility or F factor. It is transferred from one cell to another by the sex pilus. It is present in E. coli and for the conjugation to take place; bacteria can also belong to different species.
5. Plasmids can be classified into how many types depending on the genes present for their transformation?
a) 1
b) 2
c) 3
d) 4
Answer
Answer: b [Reason:] Plasmids can be said as self-mobilizable and mobilizable. They are self mobilizable in the case they contain all the genes necessary to direct its own transfer. Mobilizable are those plasmids which don’t carry all the genes necessary for their transfer but they can be transferred if the genes are present somewhere in the host.
6. Viral infection can also be used to take up the DNA by the cells. The statement is true or false?
a) True
b) False
Answer
Answer: a [Reason:] Viral infection can be used to take up the DNA by the cells. It is all because of viral coat and the nucleic acid contained within has no role to play.
7. Chemical transformation refers to the methods which use chemicals in order to carry out transformation. Which of the following statements is true with respect to it?
a) Chemical transformation decreases the efficiency of transformation as compared to natural transformation
b) Ice cold calcium solution followed by heat shock is responsible for affecting the efficiency of DNA uptake
c) The mechanism responsible for it named as ‘the heat shock model’
d) Other complex mixtures such as those containing Manganese and hexamine cobalt can’t be used to affect the efficiency
Answer
Answer: b [Reason:] Chemical transformation methods increase the DNA uptake efficiency as in comparison to natural methods. The treatment by ice cold calcium solution which is followed by heat shock, is responsible for increasing the efficiency. But the exact mechanism behind it is not known till now. Other complex mixtures which comprise of cobalt, manganese etc. can be used to increase the efficiency.
8. Electroporation is also used for taking up the DNA by the cells. It constitutes of:
a) inserting the DNA into the cells via an electric shock
b) increased efficiency than both natural and chemical methods
c) causing the least amount of damage in comparison to other methods
d) decreased efficiency than both natural and chemical methods
Answer
Answer: a [Reason:] Electroporation is the method of DNA uptake via an electric shock. It is provided by varying the potential difference across the electrodes. It is having an increased efficiency as compared to other methods. But also if prolonged treatment is given, it can cause destruction. It is so because the electric shock can be at times fatal to the cell wall.
9. Transformation carried out using a particle gun is known as biolistic transformation. It falls under which category of transformation?
a) Physical
b) Chemical
c) Electrporation
d) Natural
Answer
Answer: a [Reason:] The transformation carried out using a particle gun falls under physical transformation category. Physical transformation uses some physical methods in order to carry out the transformation.
10. The particle gun method consists of which of the following steps?
a) The DNA of interest is absorbed onto microprojectile beads
b) These beads are often made of aluminium
c) The explosion in a gun propels a macroprojectile forward which in turn propels microprojectile beads
d) The macroprojectiles and microprojectiles both cross the perforated plate and hit the target tissue behind it
Answer
Answer: c [Reason:] The DNA of interest is adsorbed on the microprojectile beads and these are made of gold and tungsten often. The explosion in the gun propels a macroprojectile forward and in turn propels microprojectile beads. These microprojectile beads cross the perforated plate but macroprojectiles don’t. Target tissue is behind the perforated plate and the microprojectiles hit it.
Set 2
1. How will we choose which transformation method is to be used?
a) It depends on the available conditions for the reaction to take place
b) It depends on the efficiency which is required to be obtained
c) All the transformation methods can be used equivalently
d) Each reaction has been assigned a particular transformation method
Answer
Answer: b [Reason:] The choice of transformation method to be used is based upon the efficiency which is desired in the reaction which has to take place.
2. The cell in which the recombinant molecules are propagated is termed as:
a) host
b) vector
c) plasmid
d) carrier
Answer
Answer: a [Reason:] Hosts are the cells which are used for propagation of recombinant molecules. The choice of a correct host is very important.
3. Some mutations are present which assist the uptake of DNA. Which of the statement is incorrect for it?
a) deoR is such a mutation which assists the uptake of DNA
b) It is a transcriptional regulator
c) It is having DNA binding activity
d) It controls expression of a set of genes involved ribonucleoside catabolism
Answer
Answer: d [Reason:] There are various factors which affect the uptake of DNA by the cells. deoR is example of such a mutation which assists the uptake of DNA. It is a transcriptional regulator and is having DNA binding activity. It controls the expression of a set of genes involved in deoxyribonucleoside catabolism.
4. Endogenous DNA-degrading system is not essential in determining transformation efficiency. The given statement is true or false?
a) True
b) False
Answer
Answer: b [Reason:] Endogenous DNA-degrading system is essential in determining the transformation efficiency.
5. Which of the following is true for K strain for E. coli?
a) It contains of restriction-modification system which is encoded by hsDMRS locus
b) hsDR encodes for endonuclease which is responsible for cleaving the DNA sequence containing –AACGCNNTGC-
c) Cleavage is carried out when the second A is non methylated
d) hsDR mutation can be used for cleavage of incoming unprotected DNA
Answer
Answer: a [Reason:] It consists of K restriction-modification system which is encoded by hsDMRS locus. hsDR encodes for endonuclease which is responsible for cleaving the DNA sequencing containing –AACNNNNNNGTGC-. Cleavage takes place only in the case when the second A and the A opposite to T in the second strand is methylated. This mutation can be used to avoid cleavage of incoming unprotected DNA.
6. Methylation dependent restriction system (MDRS) are included in which class of restriction enzymes?
a) Type I
b) Type II
c) Type III
d) They are the product of mcrA, mcrB or mrr loci
Answer
Answer: d [Reason:] MDRS don’t come under the general classification of type I-III. They are the product of mcrA, mcrB and mrr loci. It would degrade DNA containing methylcytosine (mcrA, mcrB) or methyladenine (mrr).
7. Choose the incorrect statement in respect to dam and dcm genes?
a) Their enzymes are responsible for methylation of DNA
b) Dam protein methylates cytosine in –GATC-
c) Dcm methylates cytosine in-CCAGG- and –CCTGG- sequences
d) The extent of methylation also has effects on the efficiency with which the other restriction enzymes cleave the DNA in vitro
Answer
Answer: b [Reason:] The enzymes of dam and dcm genes are responsible for mrthylation of DNA. Dam protein methylates adenine in –GATC- and dcm methylates cytosine in –CCAGG- and –CCTGG- sequences. The extent of methylation also has effects on the efficiency with which the other restriction enzymes cleave DNA in vitro.
8. How many recombination systems are present in E. coli?
a) 1
b) 2
c) 3
d) 4
Answer
Answer: c [Reason:] There are mainly three recombination systems in E.coli. They are the products of recBCD, recE and recF genes.
9. Disablement is also done in plasmids. Choose the correct statement.
a) The strains carrying out the recombinant plasmids should not escape outside
b) Preferred strains are having mutations which allow their growth in wild
c) Mutations confer prototrophy
d) If the recombinants escape outside, there is no such harm
Answer
Answer: a [Reason:] Disablement is also done in plasmids, in order to ensure that the recombinant plasmids don’t escape outside. If they escape outside, it causes contamination. Preferred strains are having mutations which don’t allow their growth in wild. Mutations confer autotrophy. Autotrophy is the condition of introduction of particular metabolites in the medium because they are not synthesized. The opposite of autotrophy is called as prototrophy.
10. endA mutation is often induced in host molecules. Choose the correct statement.
a) It activates the gene for DNA-specific endonuclease
b) It enhances the yield of plasmid DNA preparations only
c) It enhances the quality of plasmid DNA preparations only
d) It enhances both the quality and yield of plasmid DNA preparations
Answer
Answer: d [Reason:] endA mutation is often induced in host molecules. It inactivates the gene for DNA-specific endonuclease. It enhances both the yield and quality of plasmid DNA.
11. lacZΔM15 represents:
a) fully present lacZ gene
b) it is not required in alpha complementation
c) it represents lacZ gene with M15 mutation
d) it is partially deleted lacZ gene which is needed for alpha complementation
Answer
Answer: d [Reason:] The representation is for a partially deleted lacZ gene and it is very important for alpha complementation.
12. The correct statement with respect to lacIq is:
a) It is mutant of lac repressor gene and decreases the level of repressor
b) It doesn’t controls the lacZ gene
c) It is important for the vectors to replicate in a low copy number
d) It doesn’t titrates out the repressor produced by wild type lac-I gene
Answer
Answer: a [Reason:] It is a mutant of lac repressor gene and decreases the level of repressor. It controls the lacZ gene and it is important for the vectors to replicate with a high copy number. It titrates out the repressor produced by wild-type lac-I gene.
Set 3
1. The disease crown gall is caused by which bacteria?
a) Agrobacterium tumefaciens
b) Agrobacterium rhizogenes
c) Both of the above given bacterium cause the disease crown gall
d) Any bacteria belonging to genera Rhizobium
Answer
Answer: a [Reason:] The disease crown gall is caused by Agrobacterium tumefaciens. Agrobacterium rhizogenes causes the disease hair root. Agrobacterium mediated transfer forms a basis for transfer of DNA in vascular plants.
2. Agrobacterium tumefaciens form ______ plasmids and Agrobacterium rhizogenes form _______ plasmids.
a) root inducing, tumour inducing
b) tumour inducing, root inducing
c) tumour inducing, shoot inducing
d) non-tumour inducing, shoot inducing
Answer
Answer: b [Reason:] The former bacterium forms tumour inducing plasmids whereas the second bacterium forms root inducing plasmids. These plasmids are large in size.
3. The region which is transferred from bacterium to the nucleus of the plant cell is called as T-DNA. Is the given statement true or false?
a) True
b) False
Answer
Answer: a [Reason:] T-DNA (Transferred DNA) is the region which is to be transported from the bacterium to the nucleus of the vascular plant and thus it is very important.
4. Transfer of T DNA depends on a set of genes called as ______ if they are present on ________
a) vir, chromosome
b) chv, tumour inducing plasmid
c) chv, chromosome
d) vir, whether they are present on tumour inducing plasmid or chromosome
Answer
Answer: c [Reason:] Transfer of TDNA depends on a set of genes known as vir if present on tumour inducing plasmids and chv if they are present on chromosome.
5. What is the function of onc genes in TDNA?
a) Tumour suppressing potential
b) Tumour inducing potential
c) Either tumour inducing or suppressing depending on the conditions
d) Act as replicative genes
Answer
Answer: b [Reason:] onc genes present in TDNA act as tumour inducing genes. Tumour inducing potential is also known as oncogenity.
6. Which of the plant growth regulators are produced by TDNA?
a) Salicyclic acid
b) Cytokinin
c) Cytokinin and Auxin
d) Jasmonic Acid
Answer
Answer: c [Reason:] TDNA is having oncogenes and apart from it also produces plant growth regulators cytokinins and auxin. These plant growth regulators are plant hormones and are called as phytohormones.
7. If a small intermediate vector system is used along with a selectable marker, then it is called as:
a) fusion plasmids
b) hybrid plasmids
c) co-integrative plasmids
d) complex plasmids
Answer
Answer: c [Reason:] Tumour inducing plasmids are very large in size and thus they can be manipulated easily. In order to overcome this, small integrating plasmids with a selectable marker is used and it is known as co-integrative plasmid. They are then further inserted into the bacterium.
8. Binary vector systems can also be used for transferring the DNA via agrobacterium. Is the given statement true or false?
a) True
b) False
Answer
Answer: a [Reason:] As, we know Ti plasmid is difficult to manipulate because eof larger size, other alternatives are used. Binary vector system contains the gene of interest flanked by border repeats. Border repeats are the sequences present in the Ti plasmid originally. With the help of it, transfer is done into the plants.
9. If transfer of DNA from Agrobacterium to plants is done via incubation of explanted material and the vector containing DNA of interest and then selection is done via selectable marker then this method is called as:
a) transformation
b) co-cultivation
c) co-transformation
d) floral dipping
Answer
Answer: b [Reason:] Co-cultivation is the method of incubation of explanted material and the vector containing DNA of interest. Further selection is done via selectable marker such as antibiotic resistance. Floral dipping is an approach used for plant Arabidopsis.
10. If gene of interest is inserted into protoplasts but the transformation is not stable, then it is called as __________ expression systems.
a) permanent
b) temporary
c) transient
d) unstable
Answer
Answer: c [Reason:] If the gene of interest is inserted into protoplasts but the transformation is not stable, then it is called as transient expression systems.
11. 35S promoter is obtained from:
a) Tobacco mosaic virus
b) Cauliflower mosaic virus
c) Agrobacterium
d) Arabdopsis
Answer
Answer: b [Reason:] 35S promoter is obtained from cauliflower mosaic virus (CaMV). It is responsible for generation of 35S transcript in infected cells.
12. Which of the following promoter is having high tissue specificity?
a) 35S promoter
b) nos promoter
c) both of the above given promoters are having high specificity
d) neither of the promoter is having high specificity
Answer
Answer: d [Reason:] Both the promoters, 35S and CaMV are having low tissue specificity. Tissue specificity can be achieved by insertion of sequences from other promoters.
13. What is the function of glyphosate?
a) It is a fungicide
b) It is an herbicide
c) It is an enzyme used in place of glucose as a carbon source
d) It is used for adding phosphate groups
Answer
Answer: b [Reason:] Glyphosate is an herbicide. It inhibits an enzyme which is necessary for shikmic acid pathway.
14. Baciullus thuringiensis is used for production of toxins which can be used as:
a) insecticides
b) pesticides
c) germicides
d) fungicides
Answer
Answer: a [Reason:] Bacillus thuringiensis is used for production of toxins which and proteinaceous in nature and are produced during sporulation. These toxins are insecticidal in nature.
15. Which of the following compounds control ripening in tomatoes?
a) Auxin
b) Cytokinin
c) Ethylene
d) Jasmonic acid
Answer
Answer: c [Reason:] Ripening of tomatoes is controlled by ethylene. It is a plant hormone. Other plant hormones such as auxin and cytokinin are growth hormones.
Set 4
1. What will be the consequence of not having an origin of replication (ori) in the vector?
a) If an ori is absent, replication of vector would not take place
b) As the cells divide after taking up the vector, both the daughter cells would be having vector
c) A colony of transformed colonies is observed
d) The vector won’t be taken up by the cell
Answer
Answer: a [Reason:] In the case ori is absent, the vector won’t be able to replicate. As the replication won’t take place, only one of the daughter cells would be having the vector. A colony of transformed colonies won’t be obtained. The puc18 ori came from a plasmid in clinical bacterial isolate and was called as pMB1.
2. It is required to distinguish between the cells that have taken up the vector and that have not. It is done by using:
a) multiple cloning site
b) origin of replication
c) high copy number
d) selectable marker
Answer
Answer: d [Reason:] Whether the cell has taken up the vector or not is distinguished by using a selectable marker. A selectable marker often used is the ampcillin resistance property. Cells having the plasmid or vector show resistance against ampicillin.
3. Multiple cloning site (MCS) is defined as:
a) site within the plasmid which contains site for many restriction enzymes
b) site within the plasmid which contains site for many restriction enzymes and they are not present anywhere else in the plasmid
c) as the site containing many sites for only one restriction enzyme
d) cloning many inserts together
Answer
Answer: b [Reason:] MCS is defined as a location in the plasmid which is having site for many restriction enzymes and they are not present anywhere else in the plasmid.
4. Size of the vector is related to having a suitable single restriction site. The statement is true or false?
a) True
b) False
Answer
Answer: a [Reason:] The size of vector is related to having a suitable single restriction site. It is so because; if the vector is large in size there are more chances of having that sequence in the vector.
5. If a restriction site is 6 nucleotides long, what are the chances of finding it in a vector?
a) Once every 46 base pairs
b) Once every 64 base pairs
c) Once every 24 base pairs
d) Once every 16 base pairs
Answer
Answer: a [Reason:] If a restriction site is 6 nucleotides long, the chances for having it in a vector are once in every 46 base pairs. It is so because there are 4 nucleotides which form the DNA and at six positions, they can form 46 combinations.
6. Which of the statement is true for pBR322?
a) It contains only an ampicillin resistance gene
b) It contains both ampicillin resistant and tetracycline resistant gene
c) The cloning site is present only in the ampicillin resistant gene
d) It is a natural vector
Answer
Answer: b [Reason:] pBR 322 is the man-made vector. It contains both ampicillin resistant and tetracycline resistant genes. The cloning site is also present in both of the genes.
7. If a plasmid is having two antibiotic resistant genes, say ampicillin resistant and chloramphenicol resistant. If the plasmid grows in ampicillin containing medium but not in chloramphenicol, what can be concluded?
a) The insert is not present in any of the gene
b) The insert is present in ampicillin gene but not in chloramphenicol gene
c) The insert is present in choramphenicol gene but not in ampicillin gene
d) The insert is present between both of the genes
Answer
Answer: c [Reason:] The insert is present in the chloramphenicol gene and not in the ampicillin gene. As the insert is present in it, it disrupts its function and hence they are not able to grow in chloramphenicol containing medium.
8. If high copy number is there, the replication is called as ______ and if low copy number is there the replication is called as ______. Fill in the blanks accordingly,
a) stringent, relaxed
b) relaxed, stringent
c) relaxed, relaxed
d) stringent, stringent
Answer
Answer: a [Reason:] If high copy number is there, the replication is known as stringent and if the copy number is low, the replication is known as relaxed.
9. Chloramphenicol amplification is carried out in various plasmids. Which of the statement is incorrect for it?
a) It is used for increasing copy number in plasmids containing pMB1 origin
b) Chloramphenicol promotes bacterial protein synthesis
c) The protein synthesis is responsible for chromosomal DNA replication
d) Chromosomal DNA replication is related to cell division
Answer
Answer: b [Reason:] Chloramphenicol amplification is used for increasing the copy number in plasmids containing pMB1 origin. It is responsible for inhibiting bacterial protein synthesis. As the bacterial protein synthesis is inhibited, chromosomal DNA replication is also inhibited. Chromosomal DNA replication is related to cell division and it is also blocked. But the plasmid replication is not inhibited and it replicates.
10. The phenomenon of not allowing the recombinants to escape into the environment is termed as:
a) blocking
b) termination
c) disablement
d) inactivation
Answer
Answer: c [Reason:] The phenomenon of not allowing the recombinants to escape into the environment is termed as disablement. It can be achieved by disabling the mob gene, it is responsible for mobilization required for conjugation to take place.
Set 5
1. When YAC is used to clone DNA. What is the size of the DNA that can be cloned?
a) Large (upto megabases)
b) Small (upto few hundred bases)
c) No size restriction
d) Medium (upto kilobases)
Answer
Answer: a [Reason:] YACs are sophisticated cloning vectors that are used for propagating large stretches of DNA which are upto a few megabases.
2. TEL is the ______ sequence derived from the ends of ribosomal RNA-encoding molecules from the macromolecules of the protozoan Tetrahyena.
a) centromeric
b) telomeric
c) can be either centromeric or telomeric
d) can be present anywhere on the chromosome
Answer
Answer: b [Reason:] TEL is the telomeric sequence derived from the ends of ribosomal RNA-encoding molecules from the macromolecules of the protozoan Tetrahyena. It is a part of YAC.
3. Choose the incorrect statement for YAC vectors.
a) The YAC molecule is approximately 10 kb in size
b) It contains both yeast origin of replication and prokaryotic origin of replication
c) It doesn’t contains ampicillin resistant gene
d) It contains TEL sequence
Answer
Answer: c [Reason:] YAC vectors are approximately 10kb in size. It contains both yeast origin of replication and prokaryotic origin of replication. It also contains TEL sequence and an ampicillin resistant gene.
4. If YAC DNA is digested with BamHI and ECoRI, how many fragments are generated?
a) 1
b) 2
c) 3
d) 4
Answer
Answer: c [Reason:] If YAC DNA is digested with BamHI and ECoRI, three fragments are generated. Two fragments are having TEL sequence and one is lacking this sequence.
5. Transformed cells in the case of YAC can be selected by the presence of both URA3 and TRP1 genes. Is the given statement true or false?
a) True
b) False
Answer
Answer: a [Reason:] Transformed cells in the case of YAC can be selected by the presence of both URA3 and TRP1 genes. The presence of both these indicates that both the arms of YAC are acquired.
6. GAL1 is a controllable promoter and is obtained from genes for galactose metabolism. It is known for encoding ______
a) UDP-galactose-4-empirase
b) Galactokinase
c) Both UDP-galactose-4-empirase and galactokinase
d) Glucokinase
Answer
Answer: b [Reason:] GAL1 is a controllable promoter and is obtained from genes for galactose metabolism. It encodes for galactokinase and GAL10 encodes for UDP-galactose-4-empirase.
7. Transcription of GAL1 and GAL10 is suppressed in the presence of _______
a) glucose
b) galactose
c) maltose
d) fructose
Answer
Answer: a [Reason:] Transcription of GAL1 and GAL10 is suppressed in the presence of glucose and elevated in the presence of galactose.
8. How many deletion variations of GAL1 promoter are there?
a) 1
b) 2
c) 3
d) 4
Answer
Answer: b [Reason:] In GAL1 promoter, there are 2 deletion variations present. These deletion variations are known as GALL and GALS.
9. Promoters such as GAL1 can be used to direct synthesis of either unmodified or fusion proteins. Is the given statement true or false?
a) True
b) False
Answer
Answer: a [Reason:] Promoters such as GAL1 can be used to direct synthesis of either unmodified or fusion proteins. The fusion proteins can incorporate products of GAL1 or other sequences such as lacZ.
10. Which of the following are advantageous to be used for expression of eukaryotic cells?
a) Prokaryotic systems
b) Yeast cells
c) Fungi cells
d) Algae cells
Answer
Answer: b [Reason:] It is advantageous to use yeast cells for expression of eukaryotic cells in place of prokaryotic cells. It is so because in yeast cells post-translational modifications can be done but these modifications are not possible in prokaryotic cells.