Which of the following statements regarding restriction endonucleases used in recombinant DNA procedures is not true?
 
  • They are isolated from bacteria
  • They are synthesized by bacteria as a mechanism of defence against bacteriophages
  • The type II enzymes, commonly used in rDNA experiments, cut dsDNA at specific recognition sequences
  • The bacterial DNA does not have recognition sequences for the restriction enzymes produced by itself
It is desirable to use restriction enzymes that create sticky ends in recombinant DNA technology procedures because this:
 
  • facilitates the action of DNA ligase
  • makes selection of recombinant DNA possible
  • increases the copy number of rDNA per cell
  • will create multiple fragments of the vector DNA
Plasmids are good cloning vectors mainly because:
 
  • they are circular
  • they replicate autonomously
  • they are extra-chromosomal DNA molecules found in many bacterial cells
  • they carry genes vital for normal survival and reproduction
In a plasmid such as pBR322:
I. Ori controls the copy number of DNA per cell
II. Multiple cloning sites are recognition sequences of common restriction enzymes
III. Genes for antibiotic resistance are used as selectable markers
 
  • Only I and II are correct
  • Only I and III are correct
  • Only II and III are correct
  • I, II, and III are correct
A plasmid has genes for resistance against ampicillin and tetracycline. The tetracycline resistant gene is insertionally inactivated by inserting a foreign DNA within the gene. The bacterial cells are transformed. The recombinant transformants:
 
  • will be killed in a medium containing ampicillin but not in a medium containing tetracycline
  • will be killed in a medium containing tetracycline but not in a medium containing ampicillin
  • will be killed in a medium containing ampicillin and in a medium containing tetracycline
  • will not be killed in a medium containing ampicillin and in a medium containing tetracycline

In agar gel electrophoresis, the restriction fragments produced by restriction enzymes:
  • move towards cathode
  • do not move at all
  • are separated according to size with smaller fragments moving farther
  • are transported on to a nitrocellulose membrane

DNA can be visualized through UV rays if it is stained with:

  • Ethidium bromide
  • Polyethylene glycol
  • Tritiated thymidine
  • Colchicine

The Ti Plasmid [ having T-DNA] is considered a natural genetic engineer and can transform:
 
  • bacterial cells
  • dicot plant cells
  • monocot plant cells
  • animal cells
Normally, microinjection and biolistics [gene gun] are used, respectively, to transform:
 
  • plant cells and animal cells
  • animal cells and plant cells
  • animal cells and bacterial cells
  • plant cells and bacterial cells
It is usually necessary to induce ‘competence’ in bacterial cells to transform them in recombinant DNA procedures mainly because:
 
  • bacterial cell has a cell wall
  • bacteria do not have a well defined nucleus and membrane bound organelles
  • DNA is a hydrophilic molecule
  • DNA is associated with positively charged histone proteins
It is possible to make human proteins in bacterial cells with rDNA experiments because:
 
  • bacterial cells replicate faster than eukaryotic cells
  • genetic code is almost universal
  • bacterial cells have plasmids that can be used as a vector
  • bacterial cells produce restriction enzymes
Polymerase chain reaction can amplify DNA, producing about 1 billion copies in 30 cycles. The correct sequence of the steps of this reaction is:
 
  • Denaturation → Annealing of primers → Extension of primers
  • Denaturation → Extension of primers → Annealing of primers
  • Extension of primers → Annealing of primers → Denaturation
  • Annealing of primers → Extension of primers → Denaturation

Taq polymerase is:
  • is a ribozyme involved in RNA splicing in eukaryotes
  • is a thermostable DNA polymerase used in PCR
  • is a key reagent in ELISA
  • an enzyme isolated from Thermus aquaticus, a fungus found in damp soils

Identify the incorrect statement:
 
  • The process of separation and purification of expressed protein before marketing is called as downstream processing
  • DNA precipitation out of a mixture of biomolecules can be achieved by treatment with a divalent cation such as calcium ion
  • Stirred-tank bioreactors have been designed for availability of oxygen throughout the process
  • Reporter genes can be used as markers for selecting successfully transformed cells
The first restriction endonuclease, whose functioning depended on a specific DNA nucleotide sequence was:
 
  • EcoR I
  • BamH I
  • Hind II
  • Sma I
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