Genetic Engineering Products

Overview of Biotechnology

Biotechnology is the use of biological techniques and engineered organisms to make products or plants and animals that have desired traits.

Learning Objectives

Describe the historical development of biotechnology

Key Takeaways

Key Points

  • For thousands of years, humankind has used biotechnology in agriculture, food production, and medicine.
  • In the late 20th and early 21st century, biotechnology has expanded to include new and diverse sciences such as genomics, recombinant gene technologies, applied immunology, and development of pharmaceutical therapies and diganostic tests.
  • Biotechnology has applications in four major industrial areas, including health care (medical), crop production and agriculture, non food (industrial) uses of crops and other products (e.g. biodegradable plastics, vegetable oil, biofuels), and environmental uses.

Key Terms

  • nanotechnology: the science and technology of creating nanoparticles and of manufacturing machines which have sizes within the range of nanometres
image

Biotechnology: Brewing (fermentation of beer) was an early application of biotechnology.

People have used biotechnology processes, such as selectively breeding animals and fermentation, for thousands of years. Late 19th and early 20th century discoveries of how microorganisms carry out commercially useful processes and how they cause disease led to the commercial production of vaccines and antibiotics. Improved methods for animal breeding have also resulted from these efforts. Scientists in the San Francisco Bay Area took a giant step forward with the discovery and development of recombinant DNA techniques in the 1970s. The field of biotechnology continues to accelerate with new discoveries and new applications expected to benefit the economy throughout the 21st century.

In its broadest definition, biotechnology is the application of biological techniques and engineered organisms to make products or modify plants and animals to carry desired traits. This definition also extends to the use of various human cells and other body parts to produce desirable products. Bioindustry refers to the cluster of companies that produce engineered biological products and their supporting businesses. Biotechnology refers to the use of the biological sciences (such as gene manipulation), often in combination with other sciences (such as materials sciences, nanotechnology, and computer software), to discover, evaluate and develop products for bioindustry. Biotechnology products have made it easier to detect and diagnose illnesses. Many of these new techniques are easier to use and some, such as pregnancy testing, can even be used at home. More than 400 clinical diagnostic devices using biotechnology products are in use today. The most important are screening techniques to protect the blood supply against contamination by AIDS and the hepatitis B and C viruses.

Applications of Genetic Engineering

Genetic engineering means the manipulation of organisms to make useful products and it has broad applications.

Learning Objectives

Describe the major applications of genetic engineering

Key Takeaways

Key Points

  • Genetic engineering has applications in medicine, research, industry and agriculture and can be used on a wide range of plants, animals and microorganisms.
  • In medicine, genetic engineering has been used to mass-produce insulin, human growth hormones, follistim (for treating infertility), human albumin, monoclonal antibodies, antihemophilic factors, vaccines, and many other drugs.
  • In research, organisms are genetically engineered to discover the functions of certain genes.
  • Industrial applications include transforming microorganisms such as bacteria or yeast, or insect mammalian cells with a gene coding for a useful protein. Mass quantities of the protein can be produced by growing the transformed organism in bioreactors using fermentation, then purifying the protein.
  • Genetic engineering is also used in agriculture to create genetically-modified crops or genetically-modified organisms.

Key Terms

  • biotechnology: The use of living organisms (especially microorganisms) in industrial, agricultural, medical, and other technological applications.
  • cloning: The production of a cloned embryo by transplanting the nucleus of a somatic cell into an ovum.

Genetic engineering, also called genetic modification, is the direct manipulation of an organism’s genome using biotechnology.

New DNA may be inserted in the host genome by first isolating and copying the genetic material of interest, using molecular-cloning methods to generate a DNA sequence; or by synthesizing the DNA, and then inserting this construct into the host organism. Genes may be removed, or “knocked out”, using a nuclease.

image

Genetically manipulated mice: Laboratory mice are genetically manipulated by deleting a gene for use in biomedical research.

Gene targeting is a different technique that uses homologous recombination to change an endogenous gene, and can be used to delete a gene, remove exons, add a gene, or introduce point mutations. Genetic engineering has applications in medicine, research, industry and agriculture and can be used on a wide range of plants, animals and microorganisms.

Genetic engineering has produced a variety of drugs and hormones for medical use. For example, one of its earliest uses in pharmaceuticals was gene splicing to manufacture large amounts of insulin, made using cells of E. coli bacteria. Interferon, which is used to eliminate certain viruses and kill cancer cells, also is a product of genetic engineering, as are tissue plasminogen activator and urokinase, which are used to dissolve blood clots.

Another byproduct is a type of human growth hormone; it’s used to treat dwarfism and is produced through genetically-engineered bacteria and yeasts. The evolving field of gene therapy involves manipulating human genes to treat or cure genetic diseases and disorders. Modified plasmids or viruses often are the messengers to deliver genetic material to the body’s cells, resulting in the production of substances that should correct the illness. Sometimes cells are genetically altered inside the body; other times scientists modify them in the laboratory and return them to the patient’s body.

Since the 1990s, gene therapy has been used in clinical trials to treat diseases and conditions such as AIDS, cystic fibrosis, cancer, and high cholesterol. Drawbacks of gene therapy are that sometimes the person’s immune system destroys the cells that have been genetically altered, and also that it is hard to get the genetic material into enough cells to have the desired effect.

Biochemical Products of Recombinant DNA Technology

Many practical applications of recombinant DNA are found in human and veterinary medicine, in agriculture, and in bioengineering.

Learning Objectives

Describe the advances made possible by recombinant DNA technology

Key Takeaways

Key Points

  • Recombinant DNA (rDNA) is widely used in biotechnology, medicine and research. Proteins and other products that result from the use of rDNA technology are found in essentially every western pharmacy, doctor’s or veterinarian’s office, medical testing laboratory, and biological research laboratory.
  • Organisms that have been manipulated using recombinant DNA technology, and products derived from those organisms have found their way into many farms, supermarkets, home medicine cabinets, and even pet shops.
  • Biochemical products of recombinant DNA technology in medicine and research include: human recombinant insulin, growth hormone, blood clotting factors, hepatitis B vaccine, and diagnosis of HIV infection.
  • Biochemical products of recombinant DNA technology in agriculture include: golden rice, herbicide-resistant crops, and insect-resistant crops.

Key Terms

  • retinoblastoma: A malignant tumour of the retina; a hereditary condition found mostly in children.
  • neurofibromatosis: A genetic disorder characterized by the presence of multiple neurofibromas under the skin
  • cystic fibrosis: An inherited condition in which the exocrine glands produce abnormally viscous mucus, causing chronic respiratory and digestive problems.
  • recombinant DNA technology: the process of taking a gene from one organism and inserting it into the DNA of another

Recombinant DNA technology is the latest biochemical analysis that came about to satisfy the need for specific DNA segments. In this process, surrounding DNA from an existing cell is clipped in the desired amount of segments so that it can be copied millions of times.

image

Construction of recombinant DNA: A foreign DNA fragment is inserted into a plasmid vector. In this example, the gene indicated by the white color is inactivated upon insertion of the foreign DNA fragment.

Recombinant DNA technology engineers microbial cells for producing foreign proteins, and its success solely depends on the precise reading of equivalent genes made with the help of bacterial cell machinery. This process has been responsible for fueling many advances related to modern molecular biology. The last two decades of cloned-DNA sequence studies have revealed detailed knowledge about gene structure as well as its organization. It has provided hints to regulatory pathways with the aid of which gene expression in myriad cell types is controlled by the cells, especially in those organisms having body plan with basic vertebrae structure.

Recombinant DNA technology, apart from being an important tool of scientific research, has also played a vital role in the diagnosis and treatment of various diseases, especially those belonging to genetic disorders.

Some of the recent advances made possible by recombinant DNA technology are:

1. Isolating proteins in large quantities: many recombinant products are now available, including follicle stimulating hormone (FSH), Follistim AQ vial, growth hormone, insulin and some other proteins.

2. Making possible mutation identification: due to this technology, people can be easily tested for mutated protein presence that can lead to breast cancer, neurofibromatosis, and retinoblastoma.

3. Hereditary diseases carrier diagnosis: tests now available to determine if a person is carrying the gene for cystic fibrosis, the Tay-Sachs diseases, Huntington’s disease or Duchenne muscular dystrophy.

4. Gene transfer from one organism to other: the advanced gene therapy can benefit people with cystic fibrosis, vascular disease, rheumatoid arthritis and specific types of cancers.

Mammalian Gene Expression in Bacteria

Bacterial genetics can be manipulated to allow for mammalian gene expression systems established in bacteria.

Learning Objectives

Describe the sequence of events in a genetically engineered expression system

Key Takeaways

Key Points

  • Recently improved methods of DNA chemical synthesis, combined with recombinant DNA technology, permit the design and relatively rapid synthesis of modest-sized genes that can be incorporated into prokaryotic cells for gene expression using genetic engineering.
  • The feasibility of this general approach was first demonstrated by the synthesis and expression of the mammalian peptide somatostatin in Escherichia coli.
  • Mammalian gene expression can be achieved in many expression hosts by utilizing the host’s naturally occurring machinery.

Key Terms

  • ribozyme: A fragment of RNA that can act as an enzyme.
  • plasmid: A circle of double-stranded DNA that is separate from the chromosomes, which is found in bacteria and protozoa.

Gene expression is the process by which information from a gene is used in the synthesis of a functional gene product. These products are often proteins and are produced after the process of translation. An expression system that is categorized as a genetic engineering product is a system specifically designed for the production of a gene product of choice. This is normally a protein, although may also be RNA, such as tRNA or a ribozyme.

The genetically engineered expression system contains the appropriate DNA sequence for the gene of choice which is engineered into a plasmid that is introduced into a bacteria host. The molecular machinery that is required to transcribe the DNA is derived from the innate and naturally occurring machinery in the host. The DNA is then transcribed into mRNA and then translated into protein products.

In a genetically engineered system, this entire process of gene expression may be induced depending on the plasmid used. In the broadest sense, mammalian gene expression includes every living cell but the term is more normally used to refer to expression as a laboratory tool. An expression system is therefore often artificial in some manner. Viruses and bacteria are an excellent example of expression systems.

The oldest and most widely used expression systems are cell-based. Expression is often done to a very high level and therefore referred to as overexpression. There are many ways to introduce foreign DNA to a cell for expression, and there are many different host cells which may be used for expression. Each expression system also has distinct advantages and liabilities.

Expression systems are normally referred to by the host and the DNA source or the delivery mechanism for the genetic material. For example, common bacterial hosts are E.coli and B. subtilis. With E. coli, DNA is normally introduced in a plasmid expression vector. The techniques for overexpression in E. coli work by increasing the number of copies of the gene or increasing the binding strength of the promoter region so as to assist transcription.

image

Bacterial Flora: E. coli is one of the most popular hosts for artificial gene expression.

Mammalian Proteins and Products

Genetic engineering enables scientists to create plants, animals, and microorganisms by manipulating genes.

Learning Objectives

Explain the advantages and disadvantages of producing genetically engineered proteins in bacteria

Key Takeaways

Key Points

  • Systems used for mass production of recombinant human proteins include bacteria, viruses, mammalian cells, animals, and plants.
  • Most processes come with advantages and disadvantages, mostly low cost. However, mammalian proteins and products produced in animals bare ethical issues.
  • A large number of mammalian proteins are being manufactured by pharmaceutical companies for use in the treatment of human diseases.

Key Terms

  • bioreactors: A device that supports a biologically active environment.

The first successful products of genetic engineering were protein drugs like insulin, which is used to treat diabetes, and growth hormone somatotropin. These proteins are made in large quantities by genetically engineered bacteria or yeast in large “bioreactors. ” Some drugs are also made in transgenic plants, such as tobacco. Other human proteins that are used as drugs require biological modifications that only the cells of mammals, such as cows, goats, and sheep, can provide. For these drugs, production in transgenic animals is a good option. Using farm animals for drug production has many advantages because they are reproducible, have flexible production, are easily maintained, and have a great delivery method (e.g. milk).

image

Synthetic Insulin: human insulin produced by recombinant DNA technology.

Recombinant DNA technology not only allows therapeutic proteins to be produced on a large scale but using the same methodology protein molecules may be purposefully engineered. Genetic modifications introduced to a protein have many advantages over chemical modifications. Genetically engineered entities are biocompatible and biodegradable. The changes are introduced in 100% of the molecules with the exclusion of rare errors in gene transcription or translation. The preparations do not contain residual amounts of harsh chemicals used in the conjugation process. Bacterial expression systems, due to their simplicity, are often not able to produce a recombinant human protein identical to the naturally occurring wild type. Bacteria did not develop sophisticated mechanisms for performing post-translational modifications that are present in higher organisms. As a consequence, an increasing number of protein therapeutics is expressed in mammalian cells. However the low cost and simplicity of cultivating bacteria is an unbeatable advantage over any other expression system and therefore E. coli is always a preferable choice both on a lab scale and in industry.

Many mammalian proteins are produced by genetic engineering. These include, in particular, an assortment of hormones and proteins for blood clotting and other blood processes. For example, tissue plasminogen activator (TPA) is a blood protein that scavenges and dissolves blood clots that may form in the final stages of the healing process. TPA is primarily used in heart patients or others suffering from poor circulation to prevent the development of clots that can be life-threatening. Heart disease is a leading cause of death in many developed countries, especially in the United States, so microbially produced TPA is in high demand. In contrast to TPA, the blood clotting factors VII, VIII, and IX are critically important for the formation of blood clots. Hemophiliacs suffer from a deficiency of one or more clotting factors and can therefore be treated with microbially produced clotting factors. In the past hemophiliacs have been treated with clotting factor extracts from pooled human blood, some of which was contaminated with viruses such as HIV and hepatitis C, putting hemophiliacs at high risk for contracting these diseases. Recombinant clotting factors have eliminated this problem.