Genetic Engineering Practice Questions
20 free Genetic Engineering practice questions for the Microbiology. Tap an option to answer — you get instant feedback, the correct answer, and a detailed explanation for every question.
Which bacterium is commonly known as the 'Natural Genetic Engineer' of plants due to its ability to transfer T-DNA into the host genome?
- A Escherichia coli
- B Agrobacterium tumefaciens
- C Bacillus thuringiensis
- D Rhizobium leguminosarum bacteria
Correct answer: Agrobacterium tumefaciens
Agrobacterium tumefaciens contains the Ti (Tumor-inducing) plasmid. It naturally transfers a specific segment of DNA, called T-DNA, into the plant cell's nucleus, where it integrates into the host genome.
What is the primary function of Restriction Endonucleases in recombinant DNA technology?
- A To join two DNA fragments together
- B To act as molecular scissors that cut DNA at specific sequences
- C To copy RNA into DNA
- D To prevent the DNA molecule from denaturing at high reaction temperatures
Correct answer: To act as molecular scissors that cut DNA at specific sequences
Restriction endonucleases recognize specific palindromic sequences in DNA and cleave the phosphodiester backbone. This produces 'sticky' or 'blunt' ends that are essential for inserting a gene of interest into a vector.
In the context of the pBR322 vector, what does 'p' stand for?
- A Protein
- B Plasmid
- C Polymerase
- D Phage
Correct answer: Plasmid
In naming conventions for vectors, 'p' denotes that the molecule is a plasmid. pBR322 was one of the first widely used versatile cloning vectors, named after its creators Bolivar and Rodriguez.
The 'Biolistics' or Gene Gun method for plant transformation uses micro-projectiles coated with DNA made of which materials?
- A Silver or Copper
- B Gold or Tungsten
- C Iron or Zinc
- D Calcium or Magnesium
Correct answer: Gold or Tungsten
Gold and tungsten are used because they are chemically inert and dense enough to penetrate plant cell walls and membranes. This physical method is particularly useful for monocots that are resistant to Agrobacterium infection.
Which enzyme is used to permanently link two DNA fragments by catalyzing the formation of phosphodiester bonds?
- A DNA Helicase
- B DNA Ligase
- C Reverse Transcriptase
- D Nuclease
Correct answer: DNA Ligase
DNA Ligase acts as molecular glue. It repairs breaks in the sugar-phosphate backbone of DNA, effectively sealing the gene of interest into the cloning vector.
What is a 'cDNA library' primarily composed of?
- A The entire genomic DNA of an organism, including all of its non-coding introns
- B DNA sequences synthesized from mature mRNA using reverse transcriptase
- C Viral DNA used for infecting plants
- D Synthetic DNA created entirely in a laboratory
Correct answer: DNA sequences synthesized from mature mRNA using reverse transcriptase
Complementary DNA (cDNA) libraries contain only the expressed sequences (exons) of a genome. This is achieved by using reverse transcriptase to convert mRNA back into DNA, making it easier to study protein-coding genes.
In the Polymerase Chain Reaction (PCR), what is the purpose of the 'Annealing' step?
- A Separation of the two DNA strands at high temperature
- B Extension of the DNA strand by Taq polymerase
- C Visualizing the DNA bands on an agarose gel
- D Binding of primers to complementary DNA sequences
Correct answer: Binding of primers to complementary DNA sequences
Annealing occurs at a lower temperature (usually 50–65°C) to allow short DNA primers to hybridize to their target sequences. These primers provide the starting point for DNA synthesis in the subsequent elongation step.
Which of the following is a selectable marker gene commonly used in plant transformation to identify successful transformants?
- A nptII gene
- B RuBisCO
- C Cytochrome c
- D Insulin gene
Correct answer: nptII gene
Selectable markers like nptII confer resistance to antibiotics such as kanamycin. Only plant cells that have successfully integrated the transgene will survive on a medium containing the antibiotic.
The 'Flavr Savr' tomato was the first genetically engineered food to be commercially sold; it was designed to:
- A Produce its own insecticide
- B Be resistant to herbicides
- C Have a longer shelf life by delaying ripening
- D Contain higher levels of Vitamin A and other nutrients
Correct answer: Have a longer shelf life by delaying ripening
The Flavr Savr tomato used antisense RNA technology to inhibit the enzyme polygalacturonase. This slowed down the degradation of pectin in the cell wall, allowing the fruit to stay firm for a longer period.
In genetic engineering, 'Blue-White screening' is used to identify:
- A Plants that have turned blue due to stress
- B The presence of nitrogen-fixing bacteria
- C The concentration of DNA in a sample
- D Recombinant plasmids containing the insert
Correct answer: Recombinant plasmids containing the insert
Blue-white screening utilizes the lacZ gene. If a gene is inserted into the lacZ site, it disrupts the production of beta-galactosidase, resulting in white colonies; non-recombinant colonies turn blue.
Which enzyme is essential for the process of 'Reverse Transcription'?
- A DNA-dependent RNA polymerase
- B Restriction enzyme Type II
- C Alkaline phosphatase
- D RNA-dependent DNA polymerase
Correct answer: RNA-dependent DNA polymerase
Reverse transcriptase is an RNA-dependent DNA polymerase. It synthesizes a complementary DNA strand using an RNA template, a process vital for retroviruses and cDNA synthesis.
Golden Rice was engineered to help solve deficiencies in which nutrient?
- A Iron
- B Protein content
- C Iodine
- D Vitamin A
Correct answer: Vitamin A
Golden Rice contains genes from daffodils and bacteria that allow it to biosynthesize beta-carotene in the endosperm. This was developed to address Vitamin A deficiency in regions where rice is a staple food.
What does the acronym 'CRISPR' stand for in gene editing technology?
- A Clustered Regularly Interspaced Short Palindromic Repeats
- B Cellular Registered Internal Short Protein Coding Regions
- C Coded Random Interspersed Single Phage Replicons
- D Corrective RNA Induced Selective Protein Removal
Correct answer: Clustered Regularly Interspaced Short Palindromic Repeats
CRISPR describes a family of DNA sequences derived from bacteriophages that previously infected the bacterium. It serves as part of the bacterial immune system and has been adapted for precise genome editing.
The 'Bt' in Bt-Cotton refers to which source organism for the insecticidal toxin gene?
- A Bacillus typhi
- B Bacteroides terrestris
- C Bordetella trematum
- D Bacillus thuringiensis
Correct answer: Bacillus thuringiensis
Bacillus thuringiensis is a soil bacterium that produces cry toxins. These proteins are lethal to specific insect pests, such as the bollworm, providing a built-in defense mechanism for the transgenic crop.
Which method of direct gene transfer involves creating temporary pores in the cell membrane using high-voltage electricity?
- A Microinjection
- B Lipofection
- C Chemical-mediated transfer
- D Electroporation
Correct answer: Electroporation
Electroporation increases the permeability of the plasma membrane by applying an electric field. This allows DNA molecules from the surrounding solution to enter the cytoplasm before the pores reseal.
A 'Shuttle Vector' is a plasmid that can:
- A Move only within one bacterial species
- B Be used only for RNA sequencing
- C Replicate in two different host organisms
- D Destroy the host cell shortly after replication
Correct answer: Replicate in two different host organisms
Shuttle vectors contain two different origins of replication and different selectable markers. This allows researchers to manipulate DNA in a simple prokaryotic system like E. coli and then move it into a eukaryotic host for expression.
What is the purpose of 'Alkaline Phosphatase' treatment in a cloning experiment?
- A To cut the DNA at a specific site
- B To increase the speed and efficiency of the PCR reaction
- C To prevent the linearized vector from self-ligating
- D To digest the RNA in the sample
Correct answer: To prevent the linearized vector from self-ligating
Alkaline phosphatase removes the 5' phosphate groups from the ends of a linearized vector. Without the 5' phosphate, DNA ligase cannot join the ends together, ensuring the vector only recircularizes if it incorporates an insert.
In DNA gel electrophoresis, DNA molecules migrate toward which electrode?
- A The positive electrode
- B The negative electrode
- C They remain stationary based on density
- D They migrate toward the center of the gel
Correct answer: The positive electrode
DNA is negatively charged due to its phosphate backbone. When an electric current is applied, the DNA fragments move through the agarose matrix toward the positive anode; smaller fragments move faster than larger ones.
What is 'Southern Blotting' used for in molecular botany?
- A To detect specific RNA sequences
- B To measure the overall rate of plant transpiration and growth
- C To detect specific DNA sequences in a genomic sample
- D To identify protein interactions
Correct answer: To detect specific DNA sequences in a genomic sample
Southern blotting involves transferring DNA fragments from an electrophoresis gel to a membrane. A labeled DNA probe is then used to hybridize with and identify specific sequences within the complex DNA mixture.
Which term refers to the uptake of 'naked' DNA from the environment by a bacterial cell?
- A Transduction
- B Bacterial conjugation
- C Transformation
- D Translation
Correct answer: Transformation
Transformation is the process where a competent cell incorporates foreign DNA from its surroundings. In the lab, cells are often made 'chemically competent' using calcium chloride and heat shock to facilitate this process.