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?

[Biotechnology-Principles-and-Processes] [class-xii ]

• Selectable marker
• Recognition sequence
• Origin of replication
• Palindromic sequence
Correct Option: C  [ Origin of replication ]

Remark: 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’.

In the context of genetic engineering, the term "heterologous host" refers to:

[Biotechnology-Principles-and-Processes] [class-xii ]

• A host cell that naturally carries the desired gene
• A host cell that is resistant to antibiotics
• A host cell that is alien or different from the source organism of the gene
• A host cell that cannot perform replication
Correct Option: C  [ A host cell that is alien or different from the source organism of the gene ]

Remark: A recombinant protein is expressed in a heterologous host (an alien host cell).

Why did Boyer's discovery that restriction enzymes leave "sticky ends" make pasting pieces of DNA together a "precise exercise"?

[Biotechnology-Principles-and-Processes] [class-xii ]

• Sticky ends allowed blunt ends to join
• Sticky ends increased the enzyme activity
• Sticky ends formed hydrogen bonds with complementary ends, facilitating ligation
• Sticky ends prevented denaturation of DNA
Correct Option: C  [ Sticky ends formed hydrogen bonds with complementary ends, facilitating ligation ]

Remark: 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.

The DNA fragments separated by electrophoresis can only be visualized when stained with ethidium bromide and exposed to UV light because:

[Biotechnology-Principles-and-Processes] [class-xii ]

• UV radiation causes the DNA to glow naturally
• Pure DNA fragments cannot be seen in visible light without staining
• Ethidium bromide absorbs visible light intensely
• The electric field causes precipitation of stained DNA
Correct Option: B  [ Pure DNA fragments cannot be seen in visible light without staining ]

Remark: You cannot see pure DNA fragments in the visible light and without staining. Staining allows visualization under UV radiation.

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:

[Biotechnology-Principles-and-Processes] [class-xii ]

• Selecting the non-recombinants
• Eliminating the transformed cells
• Selecting the transformants (cells that successfully took up any plasmid)
• Inserting the foreign DNA
Correct Option: C  [ Selecting the transformants (cells that successfully took up any plasmid) ]

Remark: 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.

Match the concepts in List-I with their appropriate functions/definitions in List-II regarding biotechnology principles:

[Biotechnology-Principles-and-Processes] [class-xii ]

• A-I, B-II, C-III, D-IV
• A-II, B-I, C-IV, D-III
• A-II, B-I, C-III, D-IV
• A-IV, B-III, C-II, D-I
Correct Option: C  [ A-II, B-I, C-III, D-IV ]

Remark: 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.

Match the types of enzymes in List-I with their primary functions in List-II, as utilized in Recombinant DNA Technology:

[Biotechnology-Principles-and-Processes] [class-xii ]

• A-II, B-I, C-III, D-IV
• A-II, B-III, C-I, D-IV
• A-III, B-II, C-IV, D-I
• A-I, B-IV, C-II, D-III
Correct Option: B  [ A-II, B-III, C-I, D-IV ]

Remark: 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.

Match the source in List-I with the related molecular tool/enzyme in List-II:

[Biotechnology-Principles-and-Processes] [class-xii ]

• A-I, B-II, C-III, D-IV
• A-II, B-I, C-IV, D-III
• A-III, B-IV, C-I, D-II
• A-IV, B-III, C-II, D-I
Correct Option: A  [ A-I, B-II, C-III, D-IV ]

Remark: 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*.

Match the essential features of a cloning vector (List-I) with their primary functions or components (List-II):

[Biotechnology-Principles-and-Processes] [class-xii ]

• A-I, B-II, C-III, D-IV
• A-II, B-I, C-IV, D-III
• A-III, B-IV, C-I, D-II
• A-IV, B-III, C-II, D-I
Correct Option: B  [ A-II, B-I, C-IV, D-III ]

Remark: 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.

Match the steps of Recombinant DNA Technology (RDT) in List-I with their corresponding description in List-II:

[Biotechnology-Principles-and-Processes] [class-xii ]

• A-III, B-II, C-I, D-IV
• A-I, B-III, C-II, D-IV
• A-III, B-I, C-II, D-IV
• A-IV, B-II, C-III, D-I
Correct Option: C  [ A-III, B-I, C-II, D-IV ]

Remark: 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.