Remark: Separation and purification are collectively called downstream processing [55, I]. Clinical trials are required for formulations in case of drugs [55, II]. Strict quality control testing is required for each product [55, III]. Formulation involves adding suitable preservatives [55, IV].
Match the bioreactor component or requirement in List-I with its specific function in List-II:
List-I (Component/Parameter)
List-II (Control/Function)
A. Agitator system
I. Provides optimal growth conditions (e.g., Temperature, pH, Oxygen)
B. Optimal growth conditions
II. Facilitates even mixing and oxygen availability
C. Vessel function
III. Biologically converts raw materials into specific products
Remark: The agitator (stirrer) facilitates even mixing and oxygen availability [49, 50, II]. Bioreactors provide optimal growth conditions (Temp, pH, O2) [51, I]. Bioreactors act as vessels converting raw materials into products [51, III]. Stirred-tank reactors are cylindrical or curved at the base to facilitate mixing [49, IV].
Match the enzyme class in List-I with its corresponding action (List-II):
List-I (Enzyme Type)
List-II (Action)
A. Restriction Endonucleases
I. Larger class of enzymes that cut DNA
B. Nucleases
II. Removes nucleotides from the ends of DNA
C. Exonucleases
III. Makes cuts at specific positions within the DNA
D. Endonucleases (general)
IV. Cut the two strands at specific points in the sugar-phosphate backbone
Remark: Restriction endonucleases cut both strands at specific points in the sugar-phosphate backbones [19, IV]. Nucleases are the larger class of enzymes [18, I]. Exonucleases remove nucleotides from the ends of DNA [18, II]. Endonucleases make cuts at specific positions within the DNA [18, III].
Match the function in List-I related to selectable markers with the expected outcome in List-II:
List-I (Function)
List-II (Outcome)
A. Selectable Marker
I. Host cells die when plated on antibiotic medium (e.g., Amp/Tet)
B. Non-transformants
II. Helps in identifying and eliminating non-transformants
C. Transformants (e.g., Amp resistant)
IV. Will grow when plated on antibiotic containing medium
D. Differential Selection (Antibiotic Inactivation)
III. Used when a recombinant plasmid loses one resistance marker due to insertion
Remark: A selectable marker identifies and eliminates non-transformants [28, II]. Non-transformants (lacking the resistance gene) will die on antibiotic medium [46, I]. Transformants (containing the resistance gene) will grow on antibiotic medium [46, IV]. Differential selection using two antibiotics is needed when one gene is inactivated due to insertion [30, 31, III].
Assertion (A): Restriction endonucleases always make cuts at specific locations within the DNA double helix. Reason (R): Each restriction endonuclease recognizes a specific palindromic nucleotide sequence in the DNA before binding and cutting.
(A) Both Assertion and Reason are true, and Reason is the correct explanation of Assertion
(B) Both Assertion and Reason are true, but Reason is not the correct explanation of Assertion
(C) Assertion is true but Reason is false
(D) Assertion is false but Reason is true
Correct Option: A [ A ]
Remark: A is True: Endonucleases make cuts at specific positions within the DNA double helix by inspecting the DNA length and cutting at specific points in the sugar-phosphate backbone. R is True: This specificity is achieved because each restriction endonuclease recognizes a specific palindromic nucleotide sequence. R correctly explains A.
Assertion (A): Genes conferring resistance to antibiotics like ampicillin and tetracycline are considered useful selectable markers for E. coli. Reason (R): Selectable markers help in identifying and eliminating non-transformants while permitting the selective growth of transformants.
(A) Both Assertion and Reason are true, and Reason is the correct explanation of Assertion
(B) Both Assertion and Reason are true, but Reason is not the correct explanation of Assertion
(C) Assertion is true but Reason is false
(D) Assertion is false but Reason is true
Correct Option: B [ B ]
Remark: A is True: Antibiotic resistance genes are commonly used selectable markers for E. coli because normal cells lack this resistance. R is True: This statement defines the primary function of a selectable marker. However, R is a definition of the general function, not the specific reason why *ampicillin* resistance genes were chosen or why they function as markers in *E. coli* (i.e., that normal E. coli does not possess resistance). Thus, R is not the correct explanation of A.
Assertion (A): For efficient uptake of plasmid DNA, bacterial cells must first be made 'competent' by treatments like incubating with divalent cations such as calcium. Reason (R): DNA is a hydrophilic molecule, preventing it from easily passing through the hydrophobic cell membrane.
(A) Both Assertion and Reason are true, and Reason is the correct explanation of Assertion
(B) Both Assertion and Reason are true, but Reason is not the correct explanation of Assertion
(C) Assertion is true but Reason is false
(D) Assertion is false but Reason is true
Correct Option: A [ A ]
Remark: A is True: Bacteria are treated with divalent cations (like calcium) to make them competent to take up DNA. R is True: DNA is hydrophilic, which is why it cannot easily pass through the cell membrane, necessitating the competency treatment. R provides the chemical justification for the requirement stated in A.
Assertion (A): Retroviruses have been disarmed and are used as vectors to deliver desirable genes into animal cells. Reason (R): The Ti plasmid of Agrobacterium tumifaciens is naturally non-pathogenic and is used to deliver genes of interest into animal cells.
(A) Both Assertion and Reason are true, and Reason is the correct explanation of Assertion
(B) Both Assertion and Reason are true, but Reason is not the correct explanation of Assertion
(C) Assertion is true but Reason is false
(D) Assertion is false but Reason is true
Correct Option: C [ C ]
Remark: A is True: Retroviruses in animals have the ability to transform cells, and scientists have disarmed them to use them as vectors for delivering genes into animal cells. R is False: Agrobacterium tumifaciens is a pathogen of several *dicot plants*. Its Ti plasmid is generally used for gene delivery into *plant cells*, not animal cells. Moreover, the original Ti plasmid causes tumors, meaning it is not naturally non-pathogenic, though it has been modified to be non-pathogenic for vector use.
Assertion (A): In Polymerase Chain Reaction (PCR), the enzyme used is an ordinary DNA polymerase, as the reaction temperature is maintained at a physiological optimum (around 37°C) throughout the cycles. Reason (R): PCR requires a thermostable DNA polymerase, like the one isolated from the bacterium Thermus aquaticus, which remains active during the high temperature denaturation steps.
(A) Both Assertion and Reason are true, and Reason is the correct explanation of Assertion
(B) Both Assertion and Reason are true, but Reason is not the correct explanation of Assertion
(C) Assertion is true but Reason is false
(D) Assertion is false but Reason is true
Correct Option: D [ D ]
Remark: A is False: PCR involves repeating cycles including denaturation at high temperatures, which would destroy ordinary DNA polymerase. It requires a thermostable enzyme, and the temperature is not maintained at 37°C throughout. R is True: A thermostable DNA polymerase (from Thermus aquaticus) is necessary because it resists inactivation during the high temperature denaturation step, allowing repeated amplification.
