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GloFish GloFish : But what's the biotechnology behind them? GloFish are a type of transgenic zebrafish (Danio rerio) that have been modified through the insertion of a green fluorescent protein (gfp) gene. Understanding the basic principles of recombinant DNA technology which we have presented here, helps one to create wonders in the industry and research areas of biotechnology.

Learning Objectives

After completing the topic, the student will be able to:

  • Understand and explore how DNA cloning permits production of multiple copies of gene of interest.
  • Analyze how restriction endonucleases cleaves DNA at specific sites and discuss how agarose gel electrophoresis separates DNA molecules.
  • Describe in-vivo and in-vitro DNA cloning and explore how genome sequences provide clues to important biological questions.
  • Define and discuss the term transgenic organisms and appreciate their importance.
  • Investigate how recombinant DNA is used to generate transgenic organisms.
  • Define and co–relate the concepts – Genomics, Proteomics, and Bioinformatics.
  • Identify how DNA sequencing helped to complete Human genome project.
  • Appreciate the advantage of using stem cells for gene therapy.
A DNA microarray A DNA microarray (commonly known as gene chip, DNA chip, or biochip) It is a collection of microscopic DNA spots attached to a solid surface. DNA microarray that reveals expression levels of 2,400 human genes. DNA microarray analysis is one of the fastest–growing new technologies in the field of genetic research.
DNA technology and applications

DNA technology is the chemical manipulation of the genotypes and resulting phenotypes of organisms such that living organisms are modified. (Genotype is the genetic make–up of an organism and phenotype is the physical appearance of an organism). The use of DNA technology has revolutionized how scientists study genetics, biochemistry, even ecology and evolutionary biology of organisms, plus has allowed the development of novel biological products, indeed whole industries are now devoted to DNA–technology based production and analysis of biological materials.

One of the great achievements of modern science has been the sequencing of the human genome, which was largely completed by 2003. The sequencing of the first complete genome, that of a bacterium, had been achieved in previous years. During the intervening years, researchers accelerated the pace of DNA sequencing, while working on other genomes, aided by the development of faster and faster sequencing machines.

These sequencing accomplishments have all depended on advances in DNA technology, starting with the invention of methods for making recombinant DNA. This is DNA in which nucleotide sequences from different sources – often different species – are combined in vitro into the same DNA molecule. The methods for making recombinant DNA are central to genetic engineering, the direct manipulation of genes for practical purposes. Applications of genetic engineering include the manufacture of hundreds of protein products, such as hormones and blood–clotting factors. Using DNA technology, scientists can make recombinant DNA and then introduce it into cultured cells that replicate the DNA and express its genes, yielding a desired protein.

DNA sequencing autoradiogram Scientist examining DNA sequencing autoradiogram on a light box Each group of four strips represents the nucleotide sequence of AGCT (Adenine – Guanine – Cytosine – Thymine) in the DNA of the nematode worm, Onchocerca volvulus, a human parasite responsible for cutaneous onchocerciasis and river blindness in tropical countries.
Revolution of rDNA technology

DNA technology has launched a revolution in the area of biotechnology, the manipulation of organisms or their components to make useful products. Practices that go back centuries are forms of biotechnology: for example, the use of microbes to make wine and cheese and the selective breeding of livestock, which exploits naturally occurring mutations and genetic recombination.

Modern biotechnology based on the manipulation of DNA in vitro differs from earlier practices by enabling scientists to modify specific genes and move them between organisms as distinct as bacteria, plants, and animals. Thus, DNA technology is now applied in areas ranging from agriculture to criminal law. Its use allows researchers in virtually all fields of biology.

In this chapter, we first describe the main techniques for manipulating DNA and then discuss how genomes are analyzed and compared at the DNA level. Finally, we survey the practical applications of DNA technology.