Lesson 3 Brief History of Biotechnology world of"engineered"products that are based in the natural world rather than on chemical and industrial processes. Biotechnology has been described as"Janus-faced"This implies that there are two sides.On one. techniques allow DNA to be manipulated to move genes from one organism to another.On the other,it involves relatively new technologies whose consequences are untested and should be met with caution. The termbiotchnologywas coind inby Karl Ereky,an Hungarian engineer.At that time,the term meant all the lines of work by which products are produced from raw materials with the aid of living organisms.Ereky envisioned a biochemical age similar to the stone and iron ages. A common misconception among teachers is the thought that biotechnology includes only DNA and genetic engineering To keep students abreast of current knowledge,teachers sometimes have emphasized the techniques of DNA science as the "end-and-all"of biotechnology.This trend has also led to a misunderstanding in the general population.Biotechnology is NOT new.Man has been manipulating living things to solve problems and improve his way of life for millennia.Early agriculture concentrated on producing food.Plants and animals were selectively bred,and microorganisms were used to make food items such as beverages,cheese,and bread The late eighteenth century and the beginning of the nineteenth century saw the advent of vaccinations crop rotation involving leguminous crops and animal drawn machinery.The end of the nineteenth century was a milestone of biology.Microorganisms were discovered.Mendel's workon genetics was accomplished,and institutes for investigating fermentation and other microbial processes were established by Koch,Pasteur,and Lister. Biotechnology at the beginning of the twentieth century began to bring industry and agriculture together.During World War I,fermentation processes were developed that produced acetone from starch and paint solvents for the rapidly growing automobile industry.Work in the 1930s was geared toward using surplus agricultural products to supply industry instead of importsor petrochemicals.The advent of World War II brought the manufacture of penicillin.The biotechnical focus moved to 5
5 Lesson 3 Brief History of Biotechnology Biotechnology seems to be leading a sudden new biological revolution. It has brought us to the brink of a world of "engineered" products that are based in the natural world rather than on chemical and industrial processes. Biotechnology has been described as "Janus-faced." This implies that there are two sides. On one, techniques allow DNA to be manipulated to move genes from one organism to another. On the other, it involves relatively new technologies whose consequences are untested and should be met with caution. The term "biotechnology" was coined in 1919 by Karl Ereky, an Hungarian engineer. At that time, the term meant all the lines of work by which products are produced from raw materials with the aid of living organisms. Ereky envisioned a biochemical age similar to the stone and iron ages. A common misconception among teachers is the thought that biotechnology includes only DNA and genetic engineering. To keep students abreast of current knowledge, teachers sometimes have emphasized the techniques of DNA science as the "end-and-all" of biotechnology. This trend has also led to a misunderstanding in the general population. Biotechnology is NOT new. Man has been manipulating living things to solve problems and improve his way of life for millennia. Early agriculture concentrated on producing food. Plants and animals were selectively bred, and microorganisms were used to make food items such as beverages, cheese, and bread. The late eighteenth century and the beginning of the nineteenth century saw the advent of vaccinations, crop rotation involving leguminous crops, and animal drawn machinery. The end of the nineteenth century was a milestone of biology. Microorganisms were discovered, Mendel's work on genetics was accomplished, and institutes for investigating fermentation and other microbial processes were established by Koch, Pasteur, and Lister. Biotechnology at the beginning of the twentieth century began to bring industry and agriculture together. During World War I, fermentation processes were developed that produced acetone from starch and paint solvents for the rapidly growing automobile industry. Work in the 1930s was geared toward using surplus agricultural products to supply industry instead of imports or petrochemicals. The advent of World War II brought the manufacture of penicillin. The biotechnical focus moved to pharmaceuticals
Thecold war"years were dominated by work with microorganisms in preparation for biological warfare, as well as antibiotics and fermentation proces Biotechnology is currently being used in many areas including agriculture,bioremediation,food processing.and energy production.DNA fingerprinting is becoming a common practice in forensics. Similar techniques were used recently to identify the bones of the last Car of Russia and several members of his family.Production of insulin and other medicines is accomplished through nof vectors that now carry the chosen gene.Immunoassays are used not only in medicine for drug level and pregnancy testing.but also by farmers to aid in detection of unsafe levels of pesticides,herbicides.and toxinson crops and in animal products provide rapid field tests for industrial chemicals in ground water,sediment,and soil.In agriculture genetic engineering is being used to produce plants that are resistant to insects,weeds,and plant diseases. A current agricutral very involves the tomat.Arecentarticle in the New Yorker magazine compared the discovery of the edible tomato that came about by early biotechnology with the new "Flavr-Sav tomato brought about through modern techniques.In the very near future.you will be given the opportunity to bite into the Flavr-Savr tomato,the first food created by the use of recombinant DNA technology ever to go on sae What will you think as you raise the tomato to your mouth?Will you hesitate?This moment may be for you as it was for Robert Gibbon Johnson in 1820 on the steps of the courthouse inSalem,New Jersey. Prior to this moment,the tomato was widely believed to be poisonous.As a large crowd watched, wo tomatoes and changed forever the human-tomato relationship.Since that time. man has sought to produce the supermarket tomato with that"ackyard favor Americans also want that tomato available year-round. New biotechnological techniques have permitted scientists to manipulate desired traits.Prior to the advancement of the methods ofrecombinant DNA,scientists were limited tothe techniques of their time cros-pollination,selective breeding.pesticides,and herbicides Today's biotechnology has its"oin chemistry,physics,and biology.The explosion in techniques has resulted in three major branches of biotechnology:geneticengineering.diagnostic techniquesand techniques 6
6 The "cold war" years were dominated by work with microorganisms in preparation for biological warfare, as well as antibiotics and fermentation processes. Biotechnology is currently being used in many areas including agriculture, bioremediation, food processing, and energy production. DNA fingerprinting is becoming a common practice in forensics. Similar techniques were used recently to identify the bones of the last Czar of Russia and several members of his family. Production of insulin and other medicines is accomplished through cloning of vectors that now carry the chosen gene. Immunoassays are used not only in medicine for drug level and pregnancy testing, but also by farmers to aid in detection of unsafe levels of pesticides, herbicides, and toxins on crops and in animal products. These assays also provide rapid field tests for industrial chemicals in ground water, sediment, and soil. In agriculture, genetic engineering is being used to produce plants that are resistant to insects, weeds, and plant diseases. A current agricultural controversy involves the tomato. A recent article in the New Yorker magazine compared the discovery of the edible tomato that came about by early biotechnology with the new "Flavr-Savr" tomato brought about through modern techniques. In the very near future, you will be given the opportunity to bite into the Flavr-Savr tomato, the first food created by the use of recombinant DNA technology ever to go on sale. What will you think as you raise the tomato to your mouth? Will you hesitate? This moment may be for you as it was for Robert Gibbon Johnson in 1820 on the steps of the courthouse in Salem, New Jersey. Prior to this moment, the tomato was widely believed to be poisonous. As a large crowd watched, Johnson consumed two tomatoes and changed forever the human-tomato relationship. Since that time, man has sought to produce the supermarket tomato with that "backyard flavor." Americans also want that tomato available year-round. New biotechnological techniques have permitted scientists to manipulate desired traits. Prior to the advancement of the methods of recombinant DNA, scientists were limited to the techniques of their time - cross-pollination, selective breeding, pesticides, and herbicides. Today's biotechnology has its "roots" in chemistry, physics, and biology . The explosion in techniques has resulted in three major branches of biotechnology: genetic engineering, diagnostic techniques, and cell/tissue techniques
Lesson 4 Dogma,DNA,and Enzymes The Central Dogma Though it comes as no surprise that the composition of DNA between different organisms is different,it is not immediately obvious why the muscle cells,blood cells,and brain cells of any one particular vertebrate areso different in their structure and composition when the DNA of every one of their cells is identical.This is the key to one of the most exciting areas of modern cell biology.In different cell types different sets of the total number of genes(genome)e expressed.In other words,different regions of the DNA are"active"in the muscle cells,blood cells,and brain cells. To understand how this difference in DNA activity can lead to differences in cell structure and composition,it is necessary to consider what is ofen known as the central dogma of molecular biology: "DNA makes RNA makes protein"In molecular terms,a gene is that portion of DNA that encodes for a single protein.The dictum "one gene makes one protein"has required some modification with the discovery that some proteins are composed of several polypeptide chains,but makes one polypeptide"rule does hold. DNA Contains the Blueprint for all Cell Proteins Messenger RNA isa precise copy (transeript)of the coded seq of nucleicacid bases in DNA,and this message is translated into a unique protein on specialist organelles(ribosomes)present in the cytoplasm of all cells.Proteins,which are largely made up of carbon (C),hydrogen(H),oxygen(0). and nitrogen(N),are constructed from 20 different,common amino acids.The versatility of proteins,the workhorse molecules of the cell,stems from the immense variety of molecular shapes that can be created by linking amino acids together in different.The smaller proteins consist of only a few dozen amino acids,whereas the larger ones may contain in excess of 200 amino acids,all linked together in a linear chain by peptide bonds As the proteins are released from the ribosome.they nique shapes,under the inluence of chemical forces that depend on the particular sequence of amino acids.So the protein primary seqence. encoded in the gene and faithfully transcribed and translated into an amino acid chain,determines the three-dimensional structure of the emerging molecule.The human body possesses some 30,000 different 7
7 Lesson 4 Dogma, DNA, and Enzymes The Central Dogma Though it comes as no surprise that the composition of DNA between different organisms is different, it is not immediately obvious why the muscle cells, blood cells, and brain cells of any one particular vertebrate are so different in their structure and composition when the DNA of every one of their cells is identical. This is the key to one of the most exciting areas of modern cell biology. In different cell types, different sets of the total number of genes (genome) are expressed. In other words, different regions of the DNA are "active" in the muscle cells, blood cells, and brain cells. To understand how this difference in DNA activity can lead to differences in cell structure and composition, it is necessary to consider what is often known as the central dogma of molecular biology: "DNA makes RNA makes protein." In molecular terms, a gene is that portion of DNA that encodes for a single protein. The dictum "one gene makes one protein" has required some modification with the discovery that some proteins are composed of several different polypeptide chains, but the "one gene makes one polypeptide" rule does hold. DNA Contains the Blueprint for all Cell Proteins Messenger RNA is a precise copy (transcript) of the coded sequence of nucleic acid bases in DNA, and this message is translated into a unique protein molecule on specialist organelles (ribosomes) present in the cytoplasm of all cells. Proteins, which are largely made up of carbon (C), hydrogen (H), oxygen (0), and nitrogen (N), are constructed from 20 different, common amino acids. The versatility of proteins, the workhorse molecules of the cell, stems from the immense variety of molecular shapes that can be created by linking amino acids together in different sequences. The smaller proteins consist of only a few dozen amino acids, whereas the larger ones may contain in excess of 200 amino acids, all linked together in a linear chain by peptide bonds. As the proteins are released from the ribosome, they fold into unique shapes, under the influence of chemical forces that depend on the particular sequence of amino acids. So the protein primary sequence, encoded in the gene and faithfully transcribed and translated into an amino acid chain, determines the three-dimensional structure of the emerging molecule. The human body possesses some 30,000 different
kinds of proteins and several million copies of many of these.Each plays a specific role-for example. hemoglobin crries oxygen in the bloodactin and myosin interact to generate muscle movementand acetylcholine receptor molecules mediate chemical transmission between nerve and muscle cells. Enzymes-Protein Biocatalysts An essential group of proteinsthe enzymesact as biological catalysts and regulate all aspects of cel metabolism.They enable breakdown of high-energy food mecules (carbohydrates)to provide energy for biological reactions,and they conrol the synthetic pathways that result in the generation of lipids(g fats,cholesterol,and other vital membrane components),carbohydrates(sugars,starch,and cellulose-the key components of plant cell walls),and many vital small for cel function Though grouped together for their capacity to speed up chemical reactions that would proceed ony very slowly at room temperature,different classes of enzymes vary greatly in their structure and function Most cells contain about a thousand different enzymes,each capable of catalyzing a unique chemical reaction
8 kinds of proteins and several million copies of many of these. Each plays a specific role - for example, hemoglobin carries oxygen in the blood, actin and myosin interact to generate muscle movement, and acetylcholine receptor molecules mediate chemical transmission between nerve and muscle cells. Enzymes - Protein Biocatalysts An essential group of proteins - the enzymes - act as biological catalysts and regulate all aspects of cell metabolism. They enable breakdown of high-energy food molecules (carbohydrates) to provide energy for biological reactions, and they control the synthetic pathways that result in the generation of lipids (e.g., fats, cholesterol, and other vital membrane components), carbohydrates (sugars, starch, and cellulose - the key components of plant cell walls), and many vital small biomolecules essential for cell function. Though grouped together for their capacity to speed up chemical reactions that would proceed only very slowly at room temperature, different classes of enzymes vary greatly in their structure and function. Most cells contain about a thousand different enzymes, each capable of catalyzing a unique chemical reaction
Lesson 5 Polymerase Chain Reaction-Xeroxing DNA Who would have thought a bacterium hanging out in a hot spring in Yelowstone National Park would spark a revolutionary new laboratory technique?The polymerase chain reaction,now widely used in research laboratories and doctor's officesrelies on the ability of DNA-copying enzymes to remain stable at high temperatures No problem for the sultry bacterium from Yellowstone tha now helps scientists produce millions of copies of a single DNA segment ina matter of hours. In nature,most organisms copy their DNA in the same way.The PCR mimics this process,only it does it ina test tube.When any cell divides,enzymes called polymerases make a copy of all the DNA in each chromosome.The first step in this process isto"two DNA chains of the double helix.As the two strands separate,DNA polymerase makes a copy using each strand as atemplate The four nucleotide bases,the building blocks of every piece of DNA,are represented by the letters A.C.Gand T,which stand for their chemical names:adenine.ytosine,guanine.and thymine.The Aon one strand always pairs with the Ton the other.whereas Calways pairs with G.The two strands are said to be complementary toeach other. To copy DNA.polymerase requires two other components a supply of the four nucleotide bases and something called a primer.DNA polymerases,whether from humans,bacteria,or viruses,cannot copya chain of DNA without a short sequence of nucleotides to"prime"the process or get it started Sothe cell has another enzyme called a primase that actually makes the first few nucleotides of the copy.This stretch of DNA is called a primer.Once the primer is made,the polymerase can take over making the rest of the new chain A PCR vial contains all the necessary components for DNA duplication:a piece of DNA,large quantities of the four nucleotides,large quantities of the primer sequence,and DNA polymerase.The polymerase is the Taq polymerase.named for which it was isolated. The three parts of the polymerase chain reaction are carried ou in the same vial.but at different temperatures.The first part of the process separates the two DNA chains in the double helix.This is done simply by heating the vial to-95 degrees centigrade (about 165 degrees Fahrenheit)for 30 sconds 9
9 Lesson 5 Polymerase Chain Reaction - Xeroxing DNA Who would have thought a bacterium hanging out in a hot spring in Yellowstone National Park would spark a revolutionary new laboratory technique? The polymerase chain reaction, now widely used in research laboratories and doctor's offices, relies on the ability of DNA-copying enzymes to remain stable at high temperatures. No problem for Thermus aquaticus, the sultry bacterium from Yellowstone that now helps scientists produce millions of copies of a single DNA segment in a matter of hours. In nature, most organisms copy their DNA in the same way. The PCR mimics this process, only it does it in a test tube. When any cell divides, enzymes called polymerases make a copy of all the DNA in each chromosome. The first step in this process is to "unzip" the two DNA chains of the double helix. As the two strands separate, DNA polymerase makes a copy using each strand as a template. The four nucleotide bases, the building blocks of every piece of DNA, are represented by the letters A, C, G, and T, which stand for their chemical names: adenine, cytosine, guanine, and thymine. The A on one strand always pairs with the T on the other, whereas C always pairs with G. The two strands are said to be complementary to each other. To copy DNA, polymerase requires two other components: a supply of the four nucleotide bases and something called a primer. DNA polymerases, whether from humans, bacteria, or viruses, cannot copy a chain of DNA without a short sequence of nucleotides to "prime" the process, or get it started. So the cell has another enzyme called a primase that actually makes the first few nucleotides of the copy. This stretch of DNA is called a primer. Once the primer is made, the polymerase can take over making the rest of the new chain. A PCR vial contains all the necessary components for DNA duplication: a piece of DNA, large quantities of the four nucleotides, large quantities of the primer sequence, and DNA polymerase. The polymerase is the Taq polymerase, named for Thermus aquaticus, from which it was isolated. The three parts of the polymerase chain reaction are carried out in the same vial, but at different temperatures. The first part of the process separates the two DNA chains in the double helix. This is done simply by heating the vial to 90-95 degrees centigrade (about 165 degrees Fahrenheit) for 30 seconds