The concept of cloning (making multiple identical copies of a template DNA) relies on the presence of which specific sequence in the DNA being replicated?
For the multiplication of any alien piece of DNA, it needs to be a part of a chromosome/plasmid which has the specific sequence known as ‘origin of replication’.
Question 342 of 535
📘 CLASS XII
In the context of genetic engineering, the term "heterologous host" refers to:
A recombinant protein is expressed in a heterologous host (an alien host cell).
Question 343 of 535
📘 CLASS XII
Why did Boyer's discovery that restriction enzymes leave "sticky ends" make pasting pieces of DNA together a "precise exercise"?
The sticky ends made pasting pieces of DNA a precise exercise because they form hydrogen bonds with their complementary cut counterparts, aiding the DNA ligase enzyme.
Question 344 of 535
📘 CLASS XII
The DNA fragments separated by electrophoresis can only be visualized when stained with ethidium bromide and exposed to UV light because:
You cannot see pure DNA fragments in the visible light and without staining. Staining allows visualization under UV radiation.
Question 345 of 535
📘 CLASS XII
In the selection process involving pBR322 where foreign DNA is inserted into *tetR*, recombinants will show resistance to ampicillin but sensitivity to tetracycline. The ampicillin resistance gene in this scenario helps in:
In this case, one antibiotic resistance gene (ampR, which is intact) helps in selecting the transformants, whereas the other (tetR, which is inactivated) helps in selection of recombinants.
Question 346 of 535
📘 CLASS XII
Match the concepts in List-I with their appropriate functions/definitions in List-II regarding biotechnology principles:
List-I (Core Concept)
List-II (Definition/Function)
A. Genetic Engineering
I. Maintenance of sterile ambiance
B. Bioprocess Engineering
II. Techniques to alter the chemistry of genetic material
C. Cloning
III. Making multiple identical copies of any template DNA
D. Anthropocentric Approach
IV. Understanding natural phenomena focused on human welfare
Genetic engineering involves techniques to alter the chemistry of genetic material (DNA/RNA). Bioprocess engineering is the maintenance of sterile (microbial contamination-free) ambience. Cloning is making multiple identical copies of any template DNA. The anthropocentric approach focuses on developing technologies for human comfort and welfare.
Question 347 of 535
📘 CLASS XII
Match the types of enzymes in List-I with their primary functions in List-II, as utilized in Recombinant DNA Technology:
List-I (Enzyme Class)
List-II (Function)
A. Restriction Endonuclease
I. Linking cut DNA molecules (joining ends)
B. Exonuclease
II. Makes cuts at specific positions within the DNA
C. DNA Ligase
III. Removes nucleotides from the ends of the DNA
D. Taq Polymerase
IV. Thermostable enzyme used for DNA amplification in vitro
Restriction endonucleases cut within DNA at specific sites. Exonucleases remove nucleotides from the ends of the DNA. DNA ligase acts on cut DNA molecules and joins their ends. Taq Polymerase (isolated from T. aquaticus) is a thermostable DNA polymerase used in PCR for amplification.
Question 348 of 535
📘 CLASS XII
Match the source in List-I with the related molecular tool/enzyme in List-II:
List-I (Organism/Source)
List-II (Associated Tool/Enzyme)
A. E. coli RY 13 Strain
I. Source of restriction enzyme EcoRI
B. Plant Cells
II. Enzyme used to break cell wall (cellulase)
C. Fungal Cells
III. Enzyme used to break cell wall (chitinase)
D. Thermus aquaticus
IV. Source of thermostable DNA polymerase (Taq)
EcoRI is isolated from *Escherichia coli* RY 13. Cellulase is used to treat plant cells. Chitinase is used to treat fungal cells. Taq polymerase is isolated from the bacterium *Thermus aquaticus*.
Question 349 of 535
📘 CLASS XII
Match the essential features of a cloning vector (List-I) with their primary functions or components (List-II):
List-I (Vector Feature)
List-II (Role)
A. Origin of Replication (ori)
I. Identifying and eliminating non-transformants
B. Selectable Marker
II. Responsible for initiating replication and controlling copy number
C. Cloning Site
III. Codes for proteins involved in plasmid replication (e.g., in pBR322)
D. rop gene
IV. Recognition site for restriction enzyme where ligation is carried out
Ori initiates replication and controls copy number. Selectable markers eliminate non-transformants. Cloning sites are recognition sites for restriction enzymes where alien DNA is linked. The *rop* gene codes for proteins involved in the replication of the plasmid pBR322.
Question 350 of 535
📘 CLASS XII
Match the steps of Recombinant DNA Technology (RDT) in List-I with their corresponding description in List-II:
List-I (RDT Step)
List-II (Description)
A. Elution
I. Procedure through which a piece of DNA is introduced into a host bacterium
B. Transformation
II. Technique used to separate DNA fragments based on size
C. Gel Electrophoresis
III. Cutting out separated DNA bands and extracting them from the gel piece
D. Spooling
IV. Physical removal of precipitated DNA threads using chilled ethanol
Elution is the extraction of purified DNA fragments from the gel. Transformation is the introduction of DNA into a host bacterium. Gel electrophoresis is the technique used to separate DNA fragments by size. Spooling is the technique used to remove the precipitated DNA threads after adding chilled ethanol.
