Unit 18
Genes and Genetic Engineering
Table of Contents
Table of Contents 1
Introduction 3
Essential Questions 4
Review 4
Lesson 18.1: DNA: Its Role in Inheritance and Protein Synthesis 5 Objectives 5 Warm-Up 5 Learn about It 6 Key Points 17 Web Links 17 Check Your Understanding 18 Challenge Yourself 19
Lesson 18.2: Genetic Engineering 20 Objectives 20 Warm-Up 20 Learn about It 22 Key Points 26 Web Links 27 Check Your Understanding 27 Challenge Yourself 29
Lesson 18.3: Uses of Genetically Modified Organisms 30 Objectives 30 Warm-Up 30 Learn about It 31 Key Points 35
Web Links 35 Check Your Understanding 36 Challenge Yourself 37
Lesson 18.4: Benefits and Risks of Using GMOs 38 Objectives 38 Warm-Up 38 Learn about It 39 Key Points 43 Web Links 43 Check Your Understanding 44 Challenge Yourself 45
Laboratory Activity 46
Performance Task 48
Self Check 49
Key Words 50
Wrap Up 51
Photo Credits 52
References 52
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EARTH AND LIFE SCIENCE | GRADE 11/12
Unit 18 Genes and Genetic Engineering
Have you ever heard of Dolly the sheep or the BT corn and talong? These are just some common terms that you may hear when trying to dig up some products of genetic manipulation in organisms. Due to the fast growing population and the ever changing environment that becomes less habitable, humans tend to intervene and do the processes on their own way. Several products available in the market are what we termed as genetically modified organisms or GMOs. GMOs are products of gene manipulation induced by humans in other organisms. Humans tend to control and improve the quality of
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products based on their own preference. Many people are against the process but some still favors the presence of these products. In this instance, the field of genetic engineering is considered as one of the fast growing field in Science. In this unit, the importance of DNA in living organisms and the role of genetic engineering in widening our understanding about it will be tackled. Do we really benefit from genetic manipulation? Can we really intervene in natural processes that happen in the development of other organisms?
Essential Questions
At the end of this unit, you should be able to answer the following questions.
● How the information in the DNA allows the transfer of genetic information and synthesis of proteins;
● What is genetic engineering; ● What are the products of genetic engineering; and ● What are the risks and benefits of using GMO products?
Review
● Biotechnology is the development of products by modifying living systems and organisms. They often involve manipulation of microorganisms to create products such as antibiotics, vaccines, and hormones. Traditional biotechnology includes tissue culture, natural breeding, cultivation methods, and natural regeneration.
● Deoxyribonucleic acid (DNA) is a biopolymer comprised of two antiparallel complementary strands. It is a double helix with the phosphate-sugar backbone and stacks of nitrogenous bases.
● Nucleotides are monomers of DNA molecules. They contain a phosphate group, a nitrogenous base, and a five-carbon sugar.
● Deoxyribose is a five-carbon sugar in which the 2-hydroxyl group (-OH) is reduced to a hydrogen (H).
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Lesson 18.1: DNA: Its Role in Inheritance and Protein Synthesis
Objectives In this lesson, you should be able to:
● discuss the importance of DNA; ● explain the central dogma of cell; and ● explain the importance of proteins in organisms.
Each cell contain genetic materials that are transferred to the daughter cells after a single round of cell division. In organismic level, the genetic materials allow the individual to exhibit similar traits from the parents. What is the basic unit for these genetic materials? Ho do they aid in heredity and trait expression?
Warm-Up Banana DNA Extraction DNA contain the basic information about the identity of an organisms. In this activity, DNA will be extracted from the banana using simple chemical present in your household. Materials:
● large banana ● distilled water ● colorless shampoo or liquid
soap containing EDTA ● table salt ● isopropyl or rubbing alcohol ● ice ● test tube ● beaker
● ziplock bag ● plastic cups ● tape (optional) ● plastic spoons ● measuring spoons ● measuring cup ● coffee filter ● medicine dropper ● glass rod
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Procedure: 1. Mix 1/2 cup of distilled water and one piece of banana in the ziplock bag. Zip
the bag and crush the banana. Make sure to completely crush the banana. 2. Pour crush banana mixture in the beaker. 3. In a plastic cup, combine one teaspoon of soap together with the 1/4
teaspoon of salt and two tablespoons of distilled water. Stir until everything is dissolved.
4. Afterwards, transfer two tablespoons of the banana mixture to the cup. Stip for 10 minutes.
5. Using the filter paper, filter the solution in a beaker, collect the liquid component or the filtrate.
6. Using a medicine dropper, get some banana filtrate and transfer to the test tube with cold alcohol.
7. Set aside the test tube for 5 minutes. Do not shake. 8. Observe the formation of white material from the solution as a precipitate is
DNA. 9. By rotating a glass rod within the test tube, collect the precipitated DNA.
Guide Questions:
1. What is the importance of DNA in an organism? 2. Where do we normally use extracted DNA? 3. Where do we usually extract DNA? 4. What is the general method used to extract the DNA.
Learn about It
The deoxyribonucleic acid or the DNA is the basic hereditary unit in all organisms. Every single cell in the body of a living thing has the same set of DNA. These DNA materials are located in the nucleus of the cell and are enclosed in the nuclear membrane but small bulk is also present in the mitochondria of the cells. The DNA is responsible for storing the genetic information information that codes for the expression of different traits through the synthesis of proteins. These proteins are essential for expressing the tangible trait that can be observed in organisms.
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Discovery of the DNA The discovery of the DNA is a story created by several scientists. The following discussion focuses on people who made the discovery of DNA possible. Friedrich Miescher Friedrich Miescher, a Swiss chemist, first identified the existence of a “nuclein” inside the nucleus of the human white blood cells in 1869. Instead of just isolating and identifying the protein components of white blood cells, he came across a substance that had different chemical properties as compared to proteins. This substance had a very high phosphorus content and was resistant to protein digestion. He referred to this substance as “nuclein.” He knew that the substance was a new discovery but the scientific community took 50 years to appreciate his work. This “nuclein” is what we now know as DNA.
Friedrich Miescher Ostwald Avery (1844-1895) (1877-1955)
Oswald Avery Oswald Avery, a Canadian-American physician and medical researcher, identified DNA as a “transforming principle.” Together with Colin Macleod and Maclyn McCarty, they purified twenty gallons of bacteria to determine why a live harmless form of pneumococcus, a bacterium responsible for pneumonia, when mixed with a lethal form, was transformed from harmless to deadly.
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In 1944, their paper was published in the Journal of Experimental Medicine where they explained the nature of DNA as the transforming principle. This research paved the way for other discoveries on DNA in the 20th century.
Erwin Chargaff Erwin Chargaff, an Austro-Hungarian biochemist, identified that the DNA is responsible for heredity. After reading the paper of Avery, Chargaff validated his hypothesis on the relationship of DNA and heredity. By analyzing DNA from a wide range of species, he summarized his discoveries on the chemistry of nucleic acids in 1950. His findings were summarized as follows.
1. In all cellular DNAs, guanine units is equivalent to the number of cytosine units, and adenine units is equivalent to the thymine units. In other words, the sum of purine units equals the sum of pyrimidine units.
2. DNA isolated from different tissues of the one species are typically the same. 3. The base composition of DNA from one species remain the same with an
organism’s age, nutritional condition, or environment. 4. The base composition of DNA generally varies among species. These major
findings are now referred to as Chargaff’s rules.
Fig. 3. Chargaff’s rule in base pairing of DNA.
Rosalind Franklin Rosalind Franklin, an English chemist and X-ray crystallographer, contributed to the understanding of the structure of DNA in 1953. She worked with Maurice Wilkins, a scientist at John Randall’s laboratory at King’s College. They were able to capture two sets of photographs of DNA fibers.
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Using these high-resolution photographs, Franklin was able to calculate the dimensions of the DNA strands and found out that the phosphates were actually outside the DNA structure. Her discovery was very close to discovering the structure of the DNA but was beaten by Watson’s and Crick’s research discovery. James Watson and Francis Crick James Watson, an American molecular biologist and geneticist and Francis Crick, a British molecular biologist and neuroscientist, discovered the double-helix structure of the DNA. Watson and Crick used the existing X-ray data of the DNA to solve the structure of DNA.
Their paper was published in Nature in April 1953 and were awarded the Nobel Prize in Physiology in 1962. Maurice Wilkins was also an awardee in the same year.
James Watson Francis Crick (1928 - present) (1916 - 2004)
Structure of the DNA Deoxyribonucleic acid (DNA) contains the genetic information of almost all living organisms. The following are the characteristics of the DNA:
● It consists of nucleotides, which is composed of a five-carbon sugar (deoxyribose), a nitrogenous base, and a phosphate group.
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● There are four nitrogenous bases in a DNA— adenine (A), thymine (T), guanine (G), and cytosine (C).
● Nucleotides are named based on which nitrogenous base is present. The DNA contains two strands that are antiparallel in nature, which means they run in opposite directions. The two strands are in antiparallel position. This describes that the coding strand is running from 5’ to 3’ direction, while the other strand, template strand is in 3’ to 5’ direction. This antiparallel orientation of the strands can be attributed to the sugar and phosphate molecules that form the sugar-phosphate backbone. The central ladders of the DNA are composed of nitrogenous bases bonded to one another. In the DNA strands, adenine pairs with thymine, and cytosine pairs with guanine. This pairing was described in Chargaff’s rule. The sequence of the DNA strand contains codes of information that provide instructions for making proteins that are needed by organisms to grow and live.
Fig. 1. The double helix structure of the DNA.
Genes are short segments of DNA that are considered as the basic units of heredity. Every individual has two copies of each gene, one from the father and the other from the mother. They are responsible for all the traits that an individual inherits from their parents.
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The sperm and egg cells carry 23 chromosomes each. When they unite, there will be a total of 46 chromosomes. The only thing that makes one unique from others is the slight variations in the genes. For example, all have genes for iris colors, but the differences in the genes dictate the color of the iris. The DNA plays an important role in the synthesis of proteins. Proteins play an important role in the cells’ functions and structures. Central Dogma of Molecular Biology The central dogma of molecular biology explains the general process how the genetic information contained in the DNA is copied and distributed into next generation (daughter) cells, then transcribed into ribonucleic acid, RNA, molecules that direct the synthesis of protein molecules. Hence, the flow of genetic information starts from DNA replication, followed by transcription (to form messenger RNA), and finally, translation that yields proteins.
Fig. 2. Schematic diagram of the Central dogma of molecular biology.
Replication Replication is the process wherein DNA molecules in mother cells are duplicated during cell division and passed on to each daughter cell. Replication happens in a semiconservative manner. The synthesis of a new DNA strand is formed from an old DNA strand as the template and a new complementary strand. Replication involves three major steps:
● Stage 1: Initiation - The two complementary strands of the DNA are unzipped like a zipper. DNA helicase, unzip the double stranded DNA. Single-strand binding proteins bind temporarily to each strand to keep them separated. During this stage, the DNA is unzipped using the an enzyme, DNA helicase. This unwind the double helix strand of the DNA. The replication fork is the site within the DNA strand where DNA replication occur.
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● Stage 2: Elongation - In this stage, each strand becomes a template. The DNA polymerase adds new nucleotides to form the new strand complemented to the template strand through base pairing rules. Two new strands (leading and lagging) are synthesized in opposite directions. They continue to be built until they have fully complemented the template strand. The two strand can now be identified as the leading and the lagging strands. The replication of the leading strand is done continuously and from 5’ to 3’ manner. On the other hand, due to the opposite orientation of the lagging strand, the DNA polymerase requires to dissociate from the completed fragment and then reattach to the newly exposed segment. Afterwards, the DNA ligase will join the formed fragments in the lagging strands.
● Stage 3: Termination - When the two original strands are bound to their new complementary strands, DNA replication stops. The two new identical DNA molecules are complete then distributed to the daughter cells.
At the end of the replication, two DNA molecules are formed. Each with the old, original strand and a newly formed complementary strand.
Fig. 3. The replication process of the DNA.
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Transcription Transcription is the process wherein the genetic information in the DNA strand is transcribed to the messenger RNA (mRNA). The messenger RNA carries the message copied from the DNA to produce proteins. In this process, RNA uses complementary coding where the bases are matched up, similar to how DNA forms a double helix. The difference between RNA and DNA is that instead of thymine, RNA makes use of uracil.
Fig. 4. The transcription process of the DNA.
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Transcription has three major steps: ● Initiation of transcription – An enzyme called RNA polymerase binds to
the promoter region of the DNA. ● Elongation of the RNA transcript – The RNA polymerase moves through
the DNA template strand. For each nucleotide in the template, the enzyme adds a matching nucleotide in the RNA strand. Because more nucleotides are added to the RNA strand, the strand becomes longer.
● Termination of transcription – The RNA contains a site that binds to a protein called rho factor. This protein disrupts the binding of the RNA polymerase, template strand, and RNA molecule. It releases the RNA molecule and ends the transcription.
For higher eukaryotic organisms, the product of transcription does not directly proceed to translation. It normally requires post-transcriptional modifications before leaving the nucleus. It starts with the capping of the 5’ end with guanine triphosphate (GTP) and fixing poly-A tail on the 3’ end. This process adds protection to the mRNA once it goes out of the nucleus to the cytoplasm for translation. Another event that happen in this process is the splicing of mRNA with the use of spliceosome that removes the noncoding regions (introns) of the RNA. The segment of RNA that remains after splicing is called an exon. This process provides the needed sequence that can be translated to the correct protein.
Fig. 5. Post-trancriptional modification in mRNA.
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Translation Translation is the process wherein protein molecules are assembled from the information encoded in mRNA. In an mRNA, the instructions in building a protein come in groups of three nucleotides called codons. The start codon signals the beginning of translation. It is composed of the nucleotide sequence AUG. On the other hand, the stop codons signal the end of the translation. These codons can be UAA, UAG, or UGA. There are three steps involved in the translation of proteins:
● Codon recognition: Formation of an initiation complex, consist of mRNA, transfer RNA (tRNA), and the ribosomes. The ribosome is an organelle of the cell responsible for protein synthesis. It contains two subunits (small and large) that sandwich the mRNA during translation. The ribosomal unit has two sites to which the tRNA can bind. One site is called peptidyl or P site, whereas the other site is called acceptor or A site.The tRNA carries the amino acid during translation and transfers it to the ribosomes. It contains a set of three nucleotides called the anticodon. These are complementary to the mRNA’s codon. The tRNA end has the amino acid that codes for the codon of the mRNA based on the genetic code.
Fig. 6. The protein codon table for protein synthesis.
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● Peptide bond formation - This process starts with the attachment of the
tRNA to the P site. Protein chains in organisms starts with methionine that has a codon code of AUG. The tRNA binds to the start codon and starts the elongation process of the amino acids for protein synthesis. The tRNA recognizes the next codon then brings the second amino acid into the A site of the ribosome. Amino acids from both sites are joint through a chemical reaction. The translation process advances until the first tRNA is released in the exit site or the E site. The ribosome continues to move along the mRNA, and new amino acids are added to the growing polypeptide chain.
● Termination - In translocation or termination, the release factors add water molecule to the last amino acid of the chain. This addition breaks the peptide bond and separates the chain from the tRNA, releasing the newly formed protein. The elongation process stops when the stop codon that does not code for an amino acid is recognized. Another helper molecules known as release factors fit into the P site to stop the chemical reaction. Action of this protein induce the dissociation of the initiation complex back into their own, singular forms.
Fig. 7. Translation process for protein synthesis.
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Key Points
● The deoxyribonucleic acid or the DNA is the basic hereditary unit in all
organisms. ● DNA is consists of nucleotides, which are composed of a five-carbon sugar
(deoxyribose), a nitrogenous base, and a phosphate group. ● There are four nitrogenous bases in a DNA— adenine (A), thymine (T),
guanine (G), and cytosine (C). ● Nucleotides are named based on which nitrogenous base is present. ● Genes are short segments of DNA that are considered as the basic units of
heredity. ● The central dogma of molecular biology explains the general process how
the genetic information contained in the DNA is copied and distributed into next generation (daughter) cells, then transcribed into ribonucleic acid, RNA, molecules that direct the synthesis of protein molecules.
○ Replication is the process wherein DNA molecules in mother cells are duplicated during cell division and passed on to each daughter cell.
○ Transcription is the process wherein the genetic information in the DNA strand is transcribed to the messenger RNA (mRNA).
○ Translation is the process wherein protein molecules are assembled from the information encoded in mRNA.
Web Links
To learn more about DNA, you can check the following web links:
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● Craving for some interesting facts about the DNA? Visit this website: Facts Legend. 2015. ‘DNA interesting facts.’ https://factslegend.org/25-interesting-dna-facts/
● Watch the most important process inside our cells - the central dogma. Visit this site: DNA Learning Center. 2012. ‘Central Dogma of the Cell.’ Video. https://youtu.be/9kOGOY7vthk
● Watch a Ted-Ed talk about the discovery of the DNA: TedEx. 2013. ‘How I discovered DNA?.’ Video. https://youtu.be/RvdxGDJogtA
Check Your Understanding
A. Provide a summary for the important processes in the central dogma of cell.
Central Dogma of Molecular Biology
Process Starting material Important molecule that aid
the process
Product
1. DNA replication
2. transcription
3. translation
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B. Write the word true if the given statement is correct and false if otherwise. 1. Cytosine is always paired with guanine. 2. Thymine is always paired with adenine. 3. The DNA contains the basic unit of heredity which are the proteins. 4. Transcription is the process of translating mRNA to protein. 5. Replication is important in cell division to provide DNA for the two
daughter cells.
Challenge Yourself
Briefly answer the following questions.
1. What do you think will happen to the cell if DNA is not present? 2. How do you think DNA mutation happen? 3. Why do DNA sequences of different organisms share high similarities? 4. What is the role of DNA in protein synthesis? 5. What is the role of protein in the expression of different traits in organisms?
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Lesson 18.2: Genetic Engineering
Objectives In this lesson, you should be able to:
● introduce the concept of genetic engineering; ● describe the history of genetic engineering; and ● enumerate common products of genetic engineering in society.
Nowadays, genetic manipulation is very common to improve the quality of crops in agriculture, the physical appearance of livestocks, and even to improve the looks of human offspring. How does genetic engineering emerge in the field of Science? What is the scope of this particular field?
Warm-Up Polymerase chain reaction or PCR is the process of making several replicates of a target gene in the DNA strand. The process is important in genetic engineering as it allows us to create copies genes that we want to manipulate. Be familiar with PCR using this activity. A. PCR Simulation Materials:
● twizzlers ● gummy bears ● toothpicks ● drawing paper ● pencils
Procedure:
1. Group yourself into three. 2. Using the following materials: twizzlers for the backbone; gummy bears as
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chemical bases (where red is adenine, orange is cytosine, yellow is thymine, and green is guanine); and toothpicks for the hydrogen bonds, create a DNA strand model that will serve as the template strand.
3. Once done, prepare a demonstration on how DNA strands are separated during and then copied during PCR. Show the process flow using by illustrating it in a paper.
4. Afterwards, present your output to the class to verify if it is correct. B. Polymerase Chain Reaction Experiment Polymerase chain reaction (PCR) is a common technique in molecular biology and biotechnology to amplify a single copy or a few copies of a segment of DNA and generate thousands to millions of copies of a particular DNA sequence. PCR is one of the most important technique in genetic engineering. Materials:
● laptop ● Internet connection
● PCR Virtual Laboratory University of Utah. 2015. ‘PCR.’ https://learn.genetics.utah.edu/content/labs/pcr/
Procedure:
1. Open your laptop and go to the browser. 2. Using the provided link above, go to the DNA extraction activity. 3. Perform the experiment by following the instruction in the activity. 4. Answer the guide questions.
Guide Questions:
1. What are the common molecule present in the DNA? 2. What is PCR? 3. Where do we usually use PCR? 4. What is the importance of PCR in genetic engineering? 5. What is the general mechanisms of PCR?
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Learn about It
Genetic engineering is the process of modifying genes in a living organism to produce genetically modified organisms (GMOs) also known as transgenic organisms. It is a modern type of genetic modification. In this process, the gene of interest is physically removed and placed in an organism to be modified. This method is more rapid and specific than the traditional plant breeding because a gene coding a specific trait is transferred to an organism. Genetic engineering is an application of biotechnology which uses biological systems, processes, or organisms to create products that aims to improve the quality of human life. Historical Background of Genetic Engineering Genetic engineering has its root way back in the 12 000 BC where humans first tried agriculture breeding and domesticated livestocks. Recently, the definition of genetic engineering was revised and referred to as the direct transfer of external DNA from an organism to another. This process was first performed by Herbert Boyer and Stanley Cohen in early 1972.
Herbert Boyer Stanley Cohen (1936 - present) (1922 - present)
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In 1974, the first genetically modified mouse was created by Rudolf Jaenisch. This was followed by the insertion of the antibiotic resistant gene in tobacco that produced the very first genetically engineered plant. Several advances followed this milestone in the field of genetic engineering that aimed to manipulate and introduce external genes in organisms to improve its variety and form wide range of different effects in the traits of the modified individuals. The first commercialization of transgenic products or genetically modified organisms was done in 1976. One example is the artificial
production of insulin from bacteria through insertion on genes in bacteria that allowed it to produce insulin. The first plant to be commercialize was the virus resistant tobacco in China and followed by the tomato. Other products like rice, corn, and other livestock were also released as approved by the food and drug authority.
Fig. 8. Transgenic tobacco.
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General Process of Genetic Engineering Genetic engineering is done using copies of the recombinant plasmid— a circular, double-stranded DNA molecule, which is isolated and transferred to other organisms. There are four general steps in genetic engineering: DNA isolation, ligation, transformation, and selection.
Fig. 9. General process of genetic engineering in plants.
DNA Isolation In DNA Isolation, the plasmid and gene-of-interest are isolated. For example, Bt corn, a genetically modified pest-resistant plant, was grown in the Philippines against Asian corn borer (Ostrinia furnacalis), a major pest of corn. The first step in creating a pest-resistant plant is to isolate the plasmid of Agrobacterium tumefaciens and the pest-resistant gene from a bacterium, Bacillus thuringiensis (Bt). Agrobacterium tumefaciens is a Gram-negative soil bacterium that causes crown gall disease in plants. Its tumor-inducing plasmid (TI plasmid) is often used in genetic engineering because of its ability to integrate its DNA into a plant’s gene. The pest-resistant gene is obtained from the DNA of Bacillus thuringiensis. This bacterium produces a protein known as the cry1Ab toxin
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that is lethal to the larval stage of lepidopterans (moth family). Ligation In ligation, the gene is inserted into the plasmid. The next step of making a recombinant organisms is connecting the external gene to the plasmid through the use of DNA ligase enzyme. This enzyme catalyzes DNA fragments and permanently join the nucleotides of the plasmid and the external gene. The pest-resistant gene obtained from the DNA of Bacillus thuringiensis is inserted into the tumor-inducing plasmid. Transformation In transformation, the recombinant plasmid is inserted back to the bacterium. Most of the time, the transformation of the plasmid is inserted in E. coli as the expression vector. The plasmid is inserted to the bacteria through electrolysis or electric shock that opens the membrane of the bacteria and allow the entry of the plasmid. Another alternative is through the use of heat shock that forms temporary pores in the cell membrane and allows the entry of the plasmid containing the exogenous DNA. The expression vector in the form of E. coli will then be cultured and selected to get cells that perfectly express the target gene. In selection, the desired clone is identified. The transformed bacteria contain the recombinant plasmid with the gene of interest. These are normally selected using special galactose sugar called X-gal. The selected bacterium shall be used to infect the cell of corn and integrate the gene into the plant’s DNA. When the genetically modified cell divides, each daughter cell obtains the new gene. The transformed corn plant is now pest-resistant. The inserted gene in the genetically modified crop must result in the production of the toxin that is only lethal to specific target pests.
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Fig. 13. Selection of the transfected E. coli vector in the creation of BT corn.
Key Points
● Genetic engineering is the process of modifying genes in a living organism
to produce genetically modified organisms (GMOs) also known as transgenic organisms.
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● The first ever DNA manipulation experiment was performed by Herbert Boyer and Stanley Cohen in early 1972.
● In 1974, the first genetically modified mouse was created by Rudolf Jaenisch.
● In DNA Isolation, the plasmid and gene-of-interest are isolated. ● In ligation, the gene is inserted into the plasmid. ● In transformation, the recombinant plasmid is inserted back to the
bacterium.
Web Links
To learn more about genetic engineering, you can check the following web links:
● Are you okay eating GMOs? Or is it too bad? Or is it too late? Read this article to know about GMOs in your food. Rozas-Mendoza, Psyche. 2017. ‘The GMO in your food.’ https://philippinesgraphic.net/the-gmo-in-your-food/
● Watch a video and learn more about genetic engineering. Eco Wise Videos. 2015. ‘What is Genetic Engineering?’ https://youtu.be/3IsQ92KiBwM
● Can we start designing our own food? Watch this: Morehead planetarium. 2009. ‘Designer foods.’ Video. https://youtu.be/nwQkhTB0M54
Check Your Understanding
A. Provide a summary for the important processes of genetic engineering.
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Production of BT corn
Process Starting material Essential molecule that aid
the process
Product
1. DNA isolation
2. DNA litigation
3. Transformation
4. Selection process
B. Write the word true if the given statement is correct and false if otherwise. 1. Genetic engineering requires the introduction of genes from the same
modified organisms. 2. Litigation is the process of inserting the exogenous gene to the plasmid. 3. E. coli is a common expression vector for the transformation process.
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4. Plasmid is the genetic material of animals that is used for ligation. 5. Electrolysis is one process being used for ligation.
Challenge Yourself
Briefly answer the following questions.
1. Do you agree to the process of genetic engineering in inducing external genes in organisms?
2. What do you think is the advantage of genetic engineering to the society? 3. What do you think is the disadvantage of genetic engineering to the society? 4. Nowadays, where do we usually apply the principle of genetic engineering? 5. Do you think the Philippines has the potential to excel in this field to develop
exported products?
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Lesson 18.3: Uses of Genetically Modified Organisms
Objectives In this lesson, you should be able to:
● describe genetically modified organisms (GMO); ● explain the general process of making a GMO; and ● enumerate common GMO products in the market.
Genetically modified organisms or GMO are widely available in the market. Have you tried checking the labels of the product that you buy? The method of genetic engineering are now being explored to improved the quality of the products that we consume. Do you agree to the presence of GMO in the market?
Warm-Up Transgenesis in Fruit Fly Transgenesis is a common process being conducted in making genetically modified organisms. It is the process of introducing an new gene—called a transgene—into a living organism so that the organism will exhibit a new property and characteristic that can be transmitted to its offspring. Materials:
● laptop ● Internet connection
● Making a transgenic fruit fly. HHMI. 2014. ‘Transgenic fruitfly.’ http://media.hhmi.org/biointeractive/vlabs/transgenic_fly
Procedure:
1. Open your laptop and go to the browser.
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2. Using the provided link above, go to the DNA extraction activity. 3. Perform the experiment by following the instruction in the activity. 4. Answer the guide questions.
Guide Questions:
1. What is a transgenic organism? 2. What part of the DNA do we normally use for the transgenic organism? Why? 3. What do you think is the advantage of transgenic organism? 4. Do you agree on the ethical consideration of making transgenic organisms?
Learn about It
A genetically modified organism or GMO is the product of the introduction of genes from one species that is artificially extracted and placed in an unrelated organism. The external gene may come from other organisms like bacteria, insects, or animals that exhibit the desired trait. Genetically modified organisms have raised a lot of social, ethical, and even political issues. However, the process of making GMOs is still considered a revolutionary step in improving the quality of life. Genes of bacteria, plants, and animals are being modified to improve the quality of human life. Depending on the gene of interest, GMOs have many uses in the fields of agriculture and medicine. GMOs in Agriculture By modifying the genes of crops and livestock through genetic engineering, the plants and animals become more resistant to diseases. Genetically modified crops and livestock have improved quality in terms of their use (e.g. as food or feeds) and increased productivity. Crops are usually genetically modified to increase their resistance to pests and diseases by incorporating genes coding for insect or pathogen resistance. Therefore, the use of pesticides is lessened by genetically engineering crops. BT corn BT corn is a pest-resistant plant against corn-infesting larvae. Insect resistance is expressed by introducing Bacillus thuringiensis (Bt) toxin in the crops. In maize, the cry1Ab gene is inserted against corn borers. The cry1Ab gene encodes for the release of toxin in root exudates of maize. This toxin specifically affects
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lepidopterans (the corn borers) in their larval stage. It does not affect other insects such as earthworms and nematodes, animals, and even humans.
Fig. 14. Corn borer that infect corn in the Philippines.
Golden Rice Golden rice is a genetically modified rice that produces beta-carotene. This genetically modified rice is created to improve the nutritional value of rice through increased vitamin A content. Genes which code for phytoene synthase (psy) from Narcissus pseudonarcissus (commonly known as daffodil, a perennial flowering plant with bright, yellow flowers) and carotene desaturase from Erwinia uredovora (a soil-borne bacterium) are integrated in rice. As a result, yellow beta-carotene-bearing rice endosperm is produced from this combination of genes.
Fig. 15. Normal and golden rice.
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Genetically Modified Animals Unlike in crops, genetically modified animals are much more restricted in terms of production and consumption. The aim of GM animals is to improve the yields in animal breeding, genetics, and reproduction. AquAdvantage Salmon is the world’s first genetically modified animal developed for human consumption. This species of salmon has the main characteristics and traits of the Atlantic salmon and Chinook, a salmon endemic in the Pacific Ocean. As a result, this species has twice the growth rate of the Atlantic salmon where instead of having a harvestable size in three years, the AquAdvantage salmon can be harvested in 18 months.
Fig. 16. Common atlantic salmon product in the market.
GMOs in Medicine Genetic engineering is commonly used to produce biopharmaceutical drugs in the field of medicine. Different organisms are manipulated to produce the needed drug products. Most of the time, bacteria are being used to produce the needed compound that has the potential to be a drug. It is easy to grow the mass production is easy due to the asexual nature of their reproduction. The very first genetically manipulated drug that was approved to be commercialized in the market was insulin. The gene that is responsible for the production of insulin in mice is cloned and transferred to bacteria to allow it to produce the same compound. In 2000, a total of 100 genetically engineered drugs are available in American market. Common products include Remicade, Avastin, and Neulasta.
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Fig. 17. Artificially produced insulin that is enclosed in syringes.
GMOs in Environmental Remediation Bioremediation describes the process that use living organisms to clean and restore contaminated terrestrial or aquatic area. This method usually use microorganisms like bacteria and yeasts that consume contaminants and use it for their cellular metabolic pathways. Bioremediation has certain limitation since the organism being use can die due to overexposure to the contaminant because of its tolerance limit. Genetic engineering aid in bioremediation by inserting tolerance genes to the remediating organism and allow it to have a wider range of tolerance to common contaminants in the environment. Scientists usually increase the tolerance level of bacteria and yeast to high temperature, acidic environment, low oxygen levels, and high nutrient content.
Fig. 18. Common yeast that is being used for remediation.
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Key Points
● Genetically modified organisms have raised a lot of social, ethical, and
even political issues. However, the process of making GMOs is still considered a revolutionary step in improving the quality of life.
● By modifying the genes of crops and livestock through genetic engineering, the plants and animals become more resistant to diseases. Genetically modified crops and livestock have improved quality in terms of their use.
● Genetic engineering is commonly used to produce biopharmaceutical drugs in the field of medicine. Different organisms are manipulated to produce the needed drug products.
● Genetically modified organisms have posed a lot of political and ethical issues especially in the production and consumption of these products. Public and private sectors in different parts of the world have expressed their opposition to GMOs.
Web Links
For further information, you can check the following web links:
● Read on the ruling of the Supreme Court ruling on the GMO. Dela Cruz, Enrico. 2016. ‘Philippines signs new GMO rules, food industry relieved.’ https://www.reuters.com/article/us-philippines-gmo
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● PH is top grower of GM crops in SEA. Perez, Ace. 2017. ‘PH is top grower of GM crops in SEA.’ https://www.sunstar.com.ph/article/143054/
● GMO: greenpeace point of view Greenpeace. 2015. ‘Say NO to GMO.’ http://www.greenpeace.org/seasia/ph/What-we-do/Genetic-Engineering/
Check Your Understanding
A. Complete the figure below to enumerate the common products of genetic
engineering in agriculture and medicine. Common products of genetic engineering in agriculture and medicine
Agriculture Medicine
B. Write the word true if the given statement is correct and false if otherwise. 1. Insulin is one of the first genetically engineered drug available in the market. 2. Philippines prohibit the availability of GMO procust in the country. 3. GMO products can be dangerous to the people consuming the products.
GMO medicines can be easily produced through the use of insect as expression vector.
4. Bacteria are is a common option in genetic engineering in order to express the target genes.
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Challenge Yourself
Briefly answer the following questions.
1. Do you agree that GMOs are beneficial to humans? 2. What is the importance of GMO products in food security? 3. Why do you think GMO plants and animals are not good to consumers? 4. How can GMO products improve the productivity of farmers? 5. What are the common applications of GMO in medicine?
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Lesson 18.4: Benefits and Risks of Using GMOs
Objectives In this lesson, you should be able to:
● enumerate the advantage of GMO; and ● enumerate the disadvantages of GMO.
Genetically modified organisms are well distributed in the market. Some products were approved by the government for various uses in different fields. What are the benefits and risks that we might encounter to GMO products?
Warm-Up BT Corn in the Philippines Be familiar with the current status of the BT corn products in the Philippines. It is still available in the market? Are we consuming it without consent? Materials:
● laptop ● LCD projector ● BT corn documentation
● BT corn in the Philippines. IsaaaVideos. 2012. ‘Asia’s First: BT Corn in the Philippines.’ https://youtu.be/uboDidh0Qwg
Procedure:
1. With the guidance of your teacher, watch the short documentation on BT corn in the Philippines.
2. Complete the given table based on the information provided in the document.
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The advantages and disadvantages of GMO products like BT corn.
PROs CONs
3. Answer the guide questions.
Guide Questions:
1. How important corn products are in the Philippines? 2. What is the conventional method on how farmers control the pest of corn? 3. What is the role of genetic engineering in the problem of pest in corn? 4. What is BT corn? Do you agree on the production of BT corn in the
Philippines?
Learn about It
Genetically modified organisms have posed a lot of political and ethical issues especially in the production and consumption of these products. Public and private sectors in different parts of the world have expressed their opposition to GMOs. Critics impose that there might be serious and harmful outcomes from the production and consumption of GMOs. They even propose human health and environmental risks. Benefits of Using GMOs GMOs offer many benefits to humanity. Some of these are discussed below. Increased productivity GMOs enable farmers to have higher crop yields. Since GM crops are modified for a specific pest, the use of pesticide specific for that pest is reduced. In the Philippines,
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common examples of this benefit is the development of the BT corn and talong. These modified plants has the capacity to regulate corn borer even without the use of commercial pesticides in the farmland. However, at present time, the Supreme Court of the Philippines is tightly regulating the distribution of these products in the market.
Improved nutrition Genetically modified crops such as Golden Rice is improved in terms of nutrition (high in beta carotene content) to prevent eye-related problems such as blindness due to undernutrition. The development of artificially fortified crop products are emerging method of solving food security issues in third world countries. This allows the higher intake of nutrients from the crops by giving it ways on developing its own additional nutrients. Other nutrients that are commonly induced in the GMO products are vitamin C, vitamin D, and vitamin B complexes. Aided disease detection Diseases can be identified because of protein trackers in bioluminescent animals. These are the most common techniques being utilize for the detection of chronic disease. The method provide more accurate and more specific means of diagnosis for various diseases that usually take time before the sign and symptoms to appear. This benefit humans by having early detection of the disease and gives more time to prevent the spreading of worsening of the condition of the patients.
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Risks of Using GMOs GMOs also raised concerns from people because of their possible harm to the environment and human health. Some of these are discussed below. Reduced biodiversity of common insects Pest resistant crops such as BT corn lead to unintended harm to non-crop damaging insects such as larvae of monarch butterflies, which are affected by the pollen of BT corn. Since GMO crops and animals has higher tolerance to the natural pests and harsh environmental conditions, they tend to dominate and overpopulate in a certain area. Due to this, the growth of other species of plants and animals are inhibited because of tight competition with the GMO. Once this last for a long period of time, lowering of population number and extinction might happen to other species. This could wipe out normal organisms that are not transfected with external genes.
Fig. 21. Monarch butterfly that was heavily affected by the production of BT crops.
Decreased pesticide effectivity Pest resistant crops seem to reduce the need for pesticide at first, but the need might increase later on due to produced allergic reactions. Some people develop an allergic response to GM crops after exposure. Cases have been reported in the United States of America wherein people who consumed the GMO products experienced tightening of the airways and dermatitis after ingestion of the products. Presence of some unpredicted allergens in the form of proteins might have been overlooked along the process of creating the GMO.
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Fig. 22. Common label being used to indicate presence of
allergens in crop products. Higher cost for GM seeds Farmers have to buy new seeds every year. The GM seeds are patented products. Therefore, farmers cannot use second generation seeds, or such use would lead them to Supreme Court with a charge of patent infringement. Monsanto is the most famous company that produce seeds of genetically modified crop products such as corn and eggplant. The company experience several setbacks as anti-GMO product advocates filed petition to ban their products in several countries including the Philippines.
Fig. 23. Sign being used by anti-GMO activists against Monsanto.
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Religious and ethical issues Several religious and ethical issues were raised by different groups around the globe regarding the existence of genetic modification of organisms. This goes beyond the concept of God being the sole creator of all things present on Earth. Activists and ethics experts state that scientists do not have the right to manipulate things that were created by God. In the Philippines, the catholic church even released an order to their member to avoid consumption and advocacy of GMO products.
Key Points
● The GMOs offer many benefits to humanity such as increased productivity,
improved nutrition of food, and aided detection of disease for early prevention.
● GMOs also raised concerns from people because of their possible harm to the environment and human health such as reduced biodiversity of non-damaging insects, decreased pesticide effectivity, higher cost for GM seeds, and issues on religious and ethical beliefs.
Web Links
For further information, you can check the following web links:
● Know more about the benefits and risks of GMO. Food Dialogues. 2013. What Are The Benefits Of GMOs, Both Today And In The Future?’ http://www.fooddialogues.com/article/benefits-gmos-today-future/
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● Ádvantages and disadvantages of GMO. Vitanna. 2012. ‘24 Advantages and Disadvantages of GMOs.’ https://vittana.org/24-advantages-and-disadvantages-of-gmos
● Who gets the benefits from GMO? GMO answer. 2010. Órigin of Life: Panspermia.’ https://gmoanswers.com/ask/who-will-benefit-your-genetically
Check Your Understanding
A. In application to your normal life or daily living, complete the table by citing
possible benefits and risks that directly affect you if you consume GMO products.
Benefits Risks
B. Write the word true if the given statement is correct and false if otherwise.
1. GMO products are good for the population of other organisms. 2. The catholic church stand of view about GMO rooted from the
creationism theory of the bible. 3. The Food and Drug Administration id the government agency that
approves the release of GMO products in the market. 4. Most of the GMO products are safe and do not produce allergic reaction
to consumers. 5. GMO has no the potential to become an invasive species that can cause
extinction of other species in an area.
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Challenge Yourself
Briefly answer the following questions.
1. What is your opinion about the current ruling of the Supreme Court about GMO products?
2. If GMO will be prohibited in the country, do you think the problem with food security can be resolved in natural means?
3. Why is it important for GMO products to properly indicate labels in the packaging?
4. Do you agree that genetic manipulation of organisms is unethical? 5. If you will be given the chance to modify one organisms for food, what
characteristics will you put? Why?
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Laboratory Activity
Activity 18.1 Bacterial Transformation for Insulin Production
Objectives At the end of this laboratory activity, the students should be able to:
● discuss the process of isolating genes from its source; ● explain the process of DNA ligation; and ● appreciate the process of bacterial transformation.
Materials and Equipment
● pen ● tape ● scissors ● copy of the DNA templates using the provided link
● DNA templates Quipper. 2018. ‘Bacterial Transformation for Insulin Production.’ https://drive.google.com/open?id=1Pr6ovr7avFYVDV3DeJx35HB6S22Lw84d
Procedure
1. Group yourself into two members. 2. From the provided link, prepare the DNA templates for the plasmid sequence
and the mammal DNA containing the insulin gene. Cut the sequence into strips.
3. Tape together both ends of the circular plasmid DNA. Make sure that the printed portion is exposed outside the circular paper. The initial plasmid sequence will be engineered to contain insulin gene. Do the same thing for the mammalian DNA sequence.
4. Find the recognition sites on plasmid sequence and mammalian DNA. In actual thing, restriction enzyme search for the specific base pair sequence in the sequence and cut this portion. In this experiment, the restriction enzyme is your scissors. Look the sequence on both strand of the DNA and cut it as shown in the figure.
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The recognition site sequence
5. After getting the gene sequence of the insulin from the mammalian
sequence and identifying the insertion site in the plasmid using your scissors, it is now time to insert the isolated gene in the plasmid using the enzyme ligase (represented by tape in the simulation). Rebuild the plasmid by inserting the insulin genes using the transparent tape. Make sure that the templates fit together.
6. You now have constructed the plasmid vector for the transformation of your bacteria to produce insulin. Complete the table by attaching the isolated sequence from the activity.
Observations Summary of the isolated gene and plasmid vector.
Parts Output from the Activity
Isolated insulin DNA
Plasmid vector sequence
Transformed plasmid vector
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Guide Questions 1. What is a restriction enzyme? 2. What is a ligase enzyme? 3. What are the importance of these two enzymes in DNA transformation? 4. How does the transformed plasmid can be inserted in the bacteria to allow it
to produce insulin? 5. Do you think there will be difference in the insulin produce by the
recombinant bacteria and the mammals where the DNA was isolated?
Performance Task
Regulation of GMO in the Philippines
● SC ruling on BT products in the Philippines LawPhil.net. 2015. ‘BT SC ruling.’ https://www.lawphil.net/judjuris/juri2015/dec2015/pdf/gr_209271_2015.pdf
Goal
● Based on the ruling of the Philippine Supreme Court regarding the regulation of the GMO products in the market, your goal is to construct an information graphic pubmat.
Role
● You are a student studying Earth and Life Science. ● You are responsible for creating an infographic public material about the
regulations of GMO products in the Philippines. Audience
● The output will be presented to the entire class and will be evaluated by your teacher.
Situation
● The information graphic public material about GMO regulation in the Philippines will be presented in class and shall be graded by the teacher.
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Product, Performance, and Purpose ● An information graphic pubmat about GMO regulation in the Philippines
printed in A3 size paper. ● It should clearly contain the rules and regulations, any amendments and
cases where these regulations have been applied. Standards and Criteria Your performance will be graded by the following rubric.
Criteria Below Expectations, 0% to 49%
Needs Improvement
50% to 74%
Successful Performance 75% to 99%
Exemplary Performance
100%
Content. Detailed facts are presented well. Content related to the task.
Details not presented. Content is not related to the task.
Details are presented but not organized. There are some content that are not related to task.
Details are presented in an organized manner.Content are related to the task.
Details are presented in an organized matter that can be easily understood. Content are related to the task. Additional supporting details are presented.
Communication Skills. Presentation was done in a clear and logical manner.
Presentation was not done.
Presentation was done but in a disorganized and illogical manner.
Presentation was done smoothly but the concepts are presented in such a way that should be rearranged for better understanding.
Presentation was done clearly. Concepts were presented in a logical manner and easily understandable by the audience.
Self Check
This unit aims to discuss the importance of the DNA in the expression of traits of organisms. At the same time, introduce the concept of genetic engineering and cite examples of its beneficial and harmful effects. Put a check on each bos if you agree on the given statement.
Check I can…
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explain how the information in the DNA allows the transfer of genetic information and synthesis of proteins.
discuss genetic engineering and enumerate its products.
enumerate the risks and benefits of using GMO products.
Key Words
Bioremediation It is the process that use living organisms to clean and
restore contaminated terrestrial or aquatic area.
Central dogma of molecular biology
It is a general process that describes how the genetic information contained in the DNA is copied and distributed into next generation (daughter) cells, then transcribed into ribonucleic acid, RNA, molecules that direct the synthesis of protein molecules.
DNA It is the genetic material inside the nucleus of the cell and consists of nucleotides, which is composed of a five-carbon sugar (deoxyribose), a nitrogenous base, and a phosphate group.
DNA Isolation It is a process where the plasmid and gene-of-interest are isolated.
Genetic engineering
It is a process of modifying genes in a living organism to produce genetically modified organisms (GMOs) also known as transgenic organisms.
Genes These are short segments of DNA that are considered as the basic units of heredity.
Ligation It is a process where the gene is inserted into the plasmid.
Replication It is the process wherein DNA molecules in mother cells are duplicated during cell division and passed on to each daughter cell.
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Transformation It is the process of inserting the recombinant plasmid to the expression vector.
Transcription It is the process wherein the genetic information in the DNA strand is transcribed to the messenger RNA (mRNA).
Translation It is the process wherein protein molecules are assembled from the information encoded in mRNA.
Wrap Up
Genes and Genetic Engineering
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Photo Credits Rosalind Franklin. Rosalind Franklin by MRC Laboratory of Molecular Biology is
licensed under CC BY-SA 4.0 via Wikimedia Commons. Francis Crick. Francis_Crick.png by Materialscientist (talk) is licensed under CC BY
2.5 via Wikimedia Commons. Herbert Boyer. Herbert Boyer HD2005 at Podium crop by Science History Institute is
licensed under CC BY-SA 3.0 via Wikimedia Commons. Rudolf Jaenisch. Jaenisch 2003 by Sam Ogden by Whitehead inst is licensed under
CC BY-SA 3.0 via Wikimedia Commons. Fig 8. Nicotiana Tobacco Plants 1909px by Derek Ramsey is licensed under CC
BY-SA 4.0 via Wikimedia Commons. Fig 15. Golden Rice by International Rice Research Institute (IRRI) is licensed under
CC BY 2.0 via Wikimedia Commons. Fig 20. Microscopic image of yeasts by Molnarova.Lucia is licensed under CC BY-SA
4.0 via Wikimedia Commons.
References
Aleksandr Ivanovich Oparin. 2003.The Origin of Life. Massachusetts: Courier Corporation.
George Acquaah. 2012. Principles of Plant Genetics and Breeding, New Jersey: John
Wiley & Sons. Pascale Piguet and Philippe Poindron. 2012. Genetically Modified Organisms and
Genetic Engineering in Research and Therapy, Vol. 3, Switzerland: Karger Medical and Scientific Publishers.
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Rakesh Kumar Rastogi. 2007. Concepts of Biology XII. New Delhi: Rastogi Publications.
Ronald Ross Watson and Victor R. Preedy. 2015. Genetically Modified Organisms in
Food: Production, Safety, Regulation and Public Health, Massachusetts: Academic Press.
Sandra Alters. 2000.Biology: Understanding Life. Massachusetts: Jones & Bartlett
Learning. Shri Hemant Roy. 2005.Comprehensive MCQs in Biology.New Delhi: Golden Bells.
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