Genetic Engineering and Recombinant DNA
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Questions and Answers

What is the first step in generating a transgenic organism?

  • Isolation/amplification of selected genes. (correct)
  • Breeding for offspring with desired genetic modification.
  • Delivery of recombinant DNA into a host cell.
  • Fusion of selected gene with selected vector.

    • Which of the following methods is primarily used to introduce new restriction enzyme (RE) sites for cloning?

  • Gel electrophoresis.
  • Transcription.
  • Polymerase Chain Reaction (PCR). (correct)
  • DNA ligation.

    • What process is used to select genetically modified host cells?

  • PCR amplification.
  • Cloning.
  • Screening. (correct)
  • Fusion.

    • What is the approximate size of the average human protein-coding gene?

    <p>62,000 bp.</p> Signup and view all the answers

    Which of these is NOT a reason for cloning DNA?

    <p>Mutagenesis.</p> Signup and view all the answers

    What is involved in the fusion of a selected gene with a vector?

    <p>Recombining DNA.</p> Signup and view all the answers

    Which step follows after the delivery of recombinant DNA into a host cell in the process of generating a transgenic organism?

    <p>Selection of genetically modified host.</p> Signup and view all the answers

    How many base pairs approximately make up the human genome?

    <p>3.2 x 10^9 bp.</p> Signup and view all the answers

    What is the purpose of using PCR in gene modification?

    <p>To introduce point mutations in the target sequence</p> Signup and view all the answers

    Which step directly follows the isolation/amplification of selected genes in the process of generating a genetically modified organism?

    <p>Fusing the selected gene with a selected vector</p> Signup and view all the answers

    What is the primary role of vectors in genetic engineering?

    <p>To facilitate the replication of foreign DNA</p> Signup and view all the answers

    What characteristic is common to plasmids used as cloning vectors?

    <p>They typically range from 1-250 kb in size</p> Signup and view all the answers

    Which statement best describes the copy number of plasmid vectors?

    <p>Copy number is dependent on the type of replication process</p> Signup and view all the answers

    Which of the following is NOT a common type of vector used in genetic engineering?

    <p>cDNA libraries</p> Signup and view all the answers

    What is a key feature of a vector that assists in the selection of host cells with successfully delivered DNA?

    <p>Vectors carry genes conferring antibiotic resistance</p> Signup and view all the answers

    How are plasmids generally structured?

    <p>As closed circular double-stranded DNA</p> Signup and view all the answers

    What is a key feature of the plasmid vector pBR322?

    <p>It contains a rop gene regulating copy number.</p> Signup and view all the answers

    What is the purpose of the antibiotic resistance genes in pBR322?

    <p>To facilitate selection of successfully transformed cells.</p> Signup and view all the answers

    How does the removal of the rop gene affect the plasmid copy number?

    <p>Increases the number of copies to between 500-700 per cell.</p> Signup and view all the answers

    What is the function of the BamHI site in the cloning process?

    <p>It is the site for foreign DNA insertion.</p> Signup and view all the answers

    What characteristic differentiates colonies based on plasmid insertion?

    <p>Colonies with no insert appear blue, and those with insert appear white.</p> Signup and view all the answers

    What is the main advantage of relaxed replication in plasmids?

    <p>It enables the generation of numerous plasmid copies within the same cell.</p> Signup and view all the answers

    What modification to pBR322 led to an improvement in cloning efficiency?

    <p>Introduction of a Lac promoter/operator.</p> Signup and view all the answers

    Which statement about pBR322 is true?

    <p>It includes two antibiotic resistance genes for selection.</p> Signup and view all the answers

    Study Notes

    Generating Transgenic Organisms

    • Process Steps:

      • Isolate and amplify selected genes.
      • Fuse the selected gene with a suitable vector to recombine DNA.
      • Deliver the recombinant DNA into a host cell.
      • Select the genetically modified host.
      • Breed the modified host for offspring with desired genetic traits.

    • Applications:

      • DNA cloning.
      • Recombinant protein production.
      • Development of desirable phenotypes.

    Generating Recombinant DNA

    • Isolation of Genes:

      • Any DNA from any organism can be cloned, including genomic DNA, mRNA, or synthesised DNA.
      • Purposes for cloning include protein expression, sequencing, and functional studies.

    • Human Genomic Context:

      • The human genome consists of approximately 3.2 billion base pairs (bp).
      • Average size of a human protein-coding gene, including introns, is about 62,000 bp, which is roughly 0.002% of the genome.
      • The human insulin gene has a length of 1,425 bp.

    • Polymerase Chain Reaction (PCR):

      • PCR involves three steps: denaturation, annealing, and extension.
      • It can be used to introduce new restriction enzyme (RE) sites for cloning and to create point mutations in target sequences.

    Vectors in Genetic Engineering

    • Purpose of Vectors:

      • Vectors serve as molecular carriers for foreign DNA into host cells.
      • They can replicate within host cells, facilitating gene expression.
      • Often designed to allow transcription and translation of the foreign DNA.
      • Can carry antibiotic resistance genes to aid selection of successfully modified cells.

    • Common Types of Vectors:

      • Plasmids.
      • Viral vectors (e.g., phages).
      • Cosmids.
      • Artificial chromosomes.

    Plasmids as Cloning Vectors

    • Characteristics of Plasmids:

      • Naturally occurring, extrachromosomal DNA found in bacteria, 1-250 kb in size.
      • Typically exist as closed circular double-stranded DNA.
      • Can carry genes that confer useful traits, such as antibiotic resistance.
      • Copy number depends on replication type:
        • Stringent: 1-2 copies per cell.
        • Relaxed: More than 50 copies per cell.

    • Example - Plasmid Vector pBR322:

      • One of the earliest plasmids for DNA cloning, established in 1977.
      • Contains an origin of replication for plasmid replication.
      • Features a gene (rop) to regulate copy number (~20 copies/cell).
      • Includes two antibiotic resistance genes (tetracycline and ampicillin) for easy selection.

    • Improved Plasmid Vector:

      • Derived from pBR322, incorporates a Lac promoter/operator.
      • Can generate 500-700 copies per cell after removal of the rop gene, enhancing cloning efficiency and selection of colonies.

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    Description

    Explore the fascinating process of generating transgenic organisms and recombinant DNA. This quiz covers the steps involved in isolating genes, fusing them with vectors, and delivering DNA into host cells. Understand the applications and significance of genetic engineering in modern science.

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