[Biology][Practical-17] Biotechnology Questions


  • What is a plasmid? small circular DNA molecules

  • A bacteria that appear pink after Gram staining is Gram- and a bacteria that appears purple is Gram+

  • What are the steps of gram staining?


  • What is a plasmid for? Provides the host organism with genetic advantages

  • What are the 6 steps of transgenesis?

  1. The first one is to identify the gene of interest

  2. Use of restriction enzymes to produce sticky ends in the plasmid

  3. Isolation of the required gene using restriction enzymes

  4. Mixing the required gene and the plasmid with ligases

  5. Identification of the recombinant plasmid

  6. Injection of the plasmid into the host cell

  • What is a ligase for?Ligases are enzymes that can stick together 2 bits of DNA strands

  • What is a recombinant plasmid? The recombinant plasmid is the one that has successfully integrated the gene of interest into its sequence

  • What is the characteristic of the cell wall of a Gram+ bacteria? Thick peptidoglycan layer

  • What is a DNA probe? They are sequences of nucleotides that can help identify complementary sequences because they have a fluorescent dye

  • A bacteria with the following characteristics is Gram + or -?

  1. thin peptidoglycan layer
  2. outer membrane present
  3. lipopolysaccharide present

Answer: Gram -

  • Explain the principle of ELISA tests


  • The PCR part is a three-step procedure that requires five key elements :

    • the DNA samples
    • primers that bind to either side of the DNA section: they initiate the PCR reaction
    • Nucleotide bases (dNTPs) that are needed to make new DNA strands
    • Taq polymerase which adds the new DNA bases
    • A buffer that ensures the proper conditions for the reaction
  • How are sticky and blunt ends of DNA obtained? They are obtained by using restriction enzymes

  • Which of the following wells indicate the presence of a disease?
    Answer: A, C & D

  • How to identify the recombinant plasmid? usage of DNA probes

  • What is gel electrophoresis for? separation technique of DNA, RNA or protein according to their size

  • What is thermal cycling in PCR? the molecules are heated up and cooled repeatedly (20 to 40 times).

  • Explain how gel electrophoresis works?

  1. electrical field pulls the molecules
  2. charged samples pulled down the agarose gel
  3. marker to compare the sizes of the samples
  4. fluorescent dye to see the strands

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  • What does ELISA stand for? enzyme-linked immunosorbent essay

  • What is ELISA for? identification method that uses enzyme and color changes