Tools of recombinant DNA technology - restriction enzymes ligases vectors plasmids bacteriophages - Question Bank

1. The ability of a restriction enzyme to cut DNA at a specific sequence is determined by:
A) The length of the DNA molecule
B) The overall GC content of the DNA
C) The specific nucleotide sequence of the recognition site
D) The presence of ATP
2. What is a 'host cell' in the context of recombinant DNA technology?
A) The DNA fragment being inserted
B) The enzyme that cuts DNA
C) The organism that receives and replicates the recombinant DNA
D) The vector carrying the foreign DNA
3. Which restriction enzyme recognizes the sequence GAATTC and cuts between G and A?
A) HindIII
B) BamHI
C) EcoRI
D) PstI
4. What is the purpose of using a 'linker' in recombinant DNA technology?
A) To join DNA fragments
B) To introduce specific restriction sites into blunt-ended DNA
C) To increase the stability of the vector
D) To degrade unwanted DNA
5. The enzyme that adds a phosphate group to the 5' end of a DNA fragment is:
A) Ligase
B) Kinase
C) Polymerase
D) Exonuclease
6. Which of the following is a type of artificial chromosome used as a vector?
A) Plasmid
B) Bacteriophage
C) Yeast Artificial Chromosome (YAC)
D) Cosmid
7. What is the function of a 'promoter' sequence in a cloning vector, especially when expressing a foreign gene?
A) To terminate transcription
B) To initiate transcription of the inserted gene
C) To provide a site for restriction enzyme digestion
D) To replicate the vector
8. Which enzyme is used to synthesize cDNA from mRNA?
A) DNA Ligase
B) Restriction Endonuclease
C) Reverse Transcriptase
D) DNA Polymerase
9. The process of using a bacteriophage to transfer genetic material from one bacterium to another is called:
A) Transformation
B) Transfection
C) Transduction
D) Conjugation
10. What characteristic of Type III restriction enzymes makes them less ideal for routine cloning compared to Type II?
A) They require ATP and are less specific
B) They only produce blunt ends
C) They methylate the DNA after cutting
D) Their recognition sites are very rare
11. Which of the following is NOT a type of cloning vector?
A) Plasmid
B) Bacteriophage
C) Cosmid
D) Ribosome
12. What is the primary role of the 'polylinker' region in a cloning vector?
A) To initiate transcription
B) To provide multiple restriction sites for inserting foreign DNA
C) To confer antibiotic resistance
D) To regulate gene expression
13. The enzyme that unwinds DNA during replication and transcription is:
A) Ligase
B) Helicase
C) Polymerase
D) Restriction enzyme
14. What is a 'genomic library' constructed using?
A) Only plasmids
B) Only bacteriophages
C) A collection of DNA fragments from the entire genome cloned into vectors
D) Only artificial chromosomes
15. Which type of restriction enzyme has subunits that perform both restriction and modification (methylation) activities?
A) Type I
B) Type II
C) Type III
D) Type IV
16. What is the significance of the palindromic nature of many restriction enzyme recognition sites?
A) It allows the enzyme to bind more strongly
B) It ensures that the enzyme cuts both DNA strands at the same position
C) It prevents the enzyme from cutting eukaryotic DNA
D) It facilitates the replication of the DNA
17. Which of the following is a common method for selecting bacteria that have taken up a plasmid containing a reporter gene like lacZ?
A) Antibiotic selection
B) Blue-white screening
C) PCR amplification
D) Southern blotting
18. What is the function of a 'shuttle vector'?
A) To replicate in only one type of host cell
B) To replicate in two or more different host organisms
C) To degrade DNA efficiently
D) To bind DNA tightly
19. The enzyme that converts RNA into DNA is called:
A) DNA Ligase
B) Restriction Endonuclease
C) Reverse Transcriptase
D) DNA Polymerase
20. What is the advantage of using a 'suicide vector' in recombinant DNA technology?
A) It can replicate in any host cell
B) It is designed to be unstable and is eliminated from the host after integration
C) It confers antibiotic resistance
D) It allows for the insertion of very large DNA fragments
21. Which method is used to introduce foreign DNA into plant cells using Agrobacterium tumefaciens?
A) Electroporation
B) Microinjection
C) Gene gun
D) Disarmed Ti plasmid vector
22. What is the term for the DNA sequence recognized by a restriction enzyme?
A) Promoter
B) Terminator
C) Palindrome
D) Recognition site
23. Which of the following is a limitation of using bacteriophages as vectors?
A) They have a limited carrying capacity for DNA inserts
B) They are difficult to produce in large quantities
C) They can only infect specific bacterial species
D) They are easily degraded in the environment
24. The enzyme responsible for methylating DNA, often preventing cleavage by restriction enzymes that recognize the same site, is:
A) DNA Ligase
B) Methylase
C) Restriction Endonuclease
D) Reverse Transcriptase
25. Restriction enzymes are often referred to as 'molecular scissors' because:
A) They cut DNA into very small pieces
B) They cut DNA at specific recognition sequences
C) They are essential for DNA replication
D) They can repair damaged DNA
26. What does the 'ampR' gene on the pBR322 plasmid confer?
A) Resistance to ampicillin
B) Resistance to tetracycline
C) Ability to replicate in yeast
D) Ability to degrade DNA
27. Which type of bacteriophage is commonly used as a cloning vector?
A) M13
B) T4
C) Bacteriophage P1
D) All of the above
28. What is the role of a 'selectable marker' on a cloning vector?
A) To help insert foreign DNA
B) To identify and select host cells that have successfully taken up the vector
C) To increase the copy number of the plasmid
D) To degrade unwanted DNA sequences
29. A 'multiple cloning site' (MCS) in a plasmid vector is characterized by:
A) A single restriction enzyme recognition site
B) Several different restriction enzyme recognition sites clustered together
C) A region that confers antibiotic resistance
D) An origin of replication
30. What is the process of introducing recombinant DNA into bacterial cells called?
A) Transfection
B) Transformation
C) Conjugation
D) Transduction
31. Which of the following is a naturally occurring plasmid that is widely used in genetic engineering?
A) pBR322
B) Lambda phage
C) T7 phage
D) Rolling circle plasmid
32. What is the primary challenge in using 'blunt ends' for ligation compared to 'sticky ends'?
A) Blunt ends require a different ligase enzyme
B) Blunt ends are less stable and ligate less efficiently
C) Blunt ends can only be generated by specific viruses
D) Blunt ends do not have specific recognition sites
33. The most commonly used restriction enzymes in molecular cloning belong to which type?
A) Type I
B) Type II
C) Type III
D) Type IV
34. Which class of restriction enzymes requires ATP for their activity and cuts DNA at sites other than their defined recognition sequence?
A) Type I
B) Type II
C) Type III
D) Type IV
35. What is a 'cloning vector'?
A) An enzyme that cuts DNA
B) A DNA molecule used to carry a foreign gene into a host cell
C) A sequence that initiates DNA replication
D) A method for selecting transformed cells
36. The ability of a plasmid to confer antibiotic resistance to the host cell is useful because:
A) It allows the host cell to survive in antibiotic-rich media
B) It helps in the selection of transformed cells
C) It increases the rate of DNA replication
D) It prevents the plasmid from being degraded
37. Which enzyme is responsible for forming phosphodiester bonds to seal the gaps in the DNA backbone between inserted DNA and the vector?
A) Restriction Endonuclease
B) DNA Polymerase
C) DNA Ligase
D) Topoisomerase
38. What is the primary advantage of using bacteriophages over plasmids as vectors for certain applications?
A) They can carry larger DNA inserts
B) They are simpler to manipulate in the lab
C) They are more stable in the environment
D) They infect eukaryotic cells more readily
39. Which of the following is a characteristic of 'blunt ends' generated by some restriction enzymes?
A) They have single-stranded overhangs
B) They are difficult to ligate
C) They result from palindromic recognition sites
D) They are formed by enzymes like AluI
40. What is the role of the 'origin of replication' (ori) in a plasmid vector?
A) To provide a site for restriction enzyme digestion
B) To confer antibiotic resistance
C) To allow the plasmid to replicate within the host cell
D) To facilitate the insertion of foreign DNA
41. The process of inserting a foreign DNA fragment into a plasmid vector is called:
A) Transformation
B) Transduction
C) Ligation
D) Cloning
42. Bacteriophages are useful as vectors because:
A) They can only carry very small DNA fragments
B) They have a high copy number within the host cell
C) They are difficult to isolate from bacteria
D) They are prone to mutations
43. What is the term for the small, circular, extrachromosomal DNA molecules found in bacteria that are often used as vectors?
A) Chromosomes
B) Plasmids
C) Nucleoids
D) Operons
44. Which of the following is an example of a restriction enzyme?
A) Taq Polymerase
B) EcoRI
C) Lysozyme
D) RNase
45. Restriction enzymes that cut DNA symmetrically, producing 'sticky ends', are most useful for recombinant DNA technology because:
A) They degrade DNA more efficiently
B) They allow for precise joining of DNA fragments
C) They prevent unwanted mutations
D) They can cut any DNA sequence
46. What is a 'recognition site' for a restriction enzyme?
A) A region where DNA replication begins
B) A specific DNA sequence where the enzyme binds and cuts
C) A site for protein synthesis
D) A region rich in adenine and thymine bases
47. What are bacteriophages?
A) Viruses that infect bacteria
B) Bacteria that infect viruses
C) Enzymes that degrade bacterial cell walls
D) Plasmids found in bacteria
48. Which of the following is a commonly used vector in genetic engineering for cloning DNA fragments?
A) Ribosome
B) Mitochondrion
C) Plasmid
D) Lysosome
49. What is the main function of DNA ligase in recombinant DNA technology?
A) To synthesize new DNA strands
B) To join DNA fragments together
C) To degrade unwanted DNA
D) To cleave DNA at specific sites
50. Which type of enzyme is primarily used to cut DNA at specific recognition sites during recombinant DNA technology?
A) DNA Polymerase
B) Restriction Endonuclease
C) DNA Ligase
D) Reverse Transcriptase
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