Genetic Modification

Introduction:

We have seen a lot of fictional movies, books, and comics that talk about mutants and the superpowers that they have gained because of their mutations. Mutations arise from changes in the genetic code. Mutants are organisms that have an altered DNA sequence. 

Let us learn more about mutations and mutants. 

Explanation: 

Genes and the genetic code: 

Genes are the basic unit of heredity that control all the traits in an organism’s body. A gene is a section of DNA on a chromosome. They are arranged along the length of a chromosome in the nucleus. Chromosomes are the thread-like structures present in the nucleus that contain directions for cell activities. 

Deoxyribonucleic acid (DNA) is a large, complex biomolecule that contains the complete genetic information of an organism. Every cell of living organisms as well as most viruses, contains DNA.  

In 1869, Johann Friedrich discovered a chemical substance called nuclein which later came to be known as nucleic acid. This discovery led to the discovery of DNA by James Watson and Francis Crick in 1953The DNA molecule looks like two long spirals connected together, forming a twisted ladder. This shape of DNA is called a double helix. 

According to the Watson and Crick DNA model, each side of the ladder is made up of sugar-phosphate molecules and each side of the DNA was made up of a pair of chemicals called nitrogenous bases.  

DNA is made up of four distinct bases: cytosine (C), guanine (G), thymine (T), and adenine (A). These bases connect together in specific ways. Each base bonds only with its own specific match. Adenine always bonds with thymine, and guanine always bonds with cytosine. The bond that exists between each base pair is what holds the two sides together. 

What is the importance of a genetic code?  

The genetic code comprises of the DNA that determines the function of each cell. The sequence in which the base pairs are arranged in the DNA determines genetic characteristics, and this order is the same in every cell found in an individual organism.  

When cells divide during mitosis, an identical set of chromosomes is produced and a copy of the DNA molecule is made with exactly the same order of base pairs as the original. 

The genetic code ensures that every function like the formation of proteins, enzymes, etc. in our body is controlled. It is also responsible for an organism’s structure and physical appearance. For example, the corneal tissue grows only where your eyes belong and the nails grow only on your fingers and toes.  

Any change in the genetic code can lead to mutations or abnormalities in an organism. These mutations can be useful or harmful. We know that mutations can occur naturally during sexual reproduction or due to environmental factors but mutations can also be induced by the process of genetic modification or genetic engineering. There is a difference in the DNA of the numerous species found on earth. 

A genome consists of all the DNA that makes up an organism. A-T and G-C base pairs are repeated millions, if not billions, of times. The human genome is made up of approximately 3 billion base pairs. All genetic differences found in earth’s organisms are caused by variations in the number and order of these base pairs. 

Genetic engineering: 

Genetic engineering often also known as genetic modification is the process by which alterations are made in the genome of an organism. This process was discovered in 1973 when scientists Stanley Cohen and Herb Boyer first transferred DNA from one species to another. 

In genetic engineering the genetic sequence in DNA is changed intentionally so that a particular trait is produced.  A geneticist is a scientist who examines how heredity works. Geneticists use their knowledge in many innovative ways.  

Genetic engineering is used for eliminating unwanted traits, enhancing useful traits, and producing GMOs. It also has various applications in medicine. Genetic engineering can be done by replacing one base pair (A-T or C-G), deleting an entire section of DNA, or introducing an extra copy of a gene. 

It also involves extracting DNA from another organism’s genome and combining it with the DNA of that individual. 

Recombinant DNA: 

Genetic engineering uses recombinant DNA technology to produce genetically modified organisms. Recombinant DNA is made by taking a useful segment of DNA from one organism and inserting it into another organism. 

Chemicals known as restriction enzymes are used to cut the part of the DNA that is to be transferred. This segment is then inserted into a plasmid which is a small circular structure of genetic material found in bacteria. Another organism’s DNA is inserted, or spliced, into the plasmid. 

Examples of genetic engineering: 

1. Insulin production: 

Genetic engineering is used in insulin production by using recombinant DNA technology. Normally insulin is produced in the pancreas but people with type I diabetes are unable to produce insulin and have to inject insulin to control their sugar levels. Insulin is the first genetically engineered medicine created by inserting a gene from the intestine of the pig into a bacterium. 

A human insulin-producing gene is identified. A plasmid DNA of an E. coli bacterium is cut by special enzymes. The gene for insulin production is then inserted into the plasmid DNA.  

The plasmid DNA is then inserted into the E. coli bacterium, and as a result, the bacterium can produce human insulin. The insulin-producing E. coli bacteria passes this trait on to offspring and large amounts of human insulin are produced by many genetically engineered E. coli bacteria. 

2. Oil eating bacteria: 

Similarly genetic engineering has also made it easier to clean up oil spills by genetically modifying bacteria to produce substances that break down oil particle. When these genetically altered bacteria are applied directly on an oil spill, they can break some of the oil down into harmless, nontoxic substances.  

With the help of genetic engineering, we can also produce crops that are able to withstand extreme weather conditions. 

For example, barley plants possess a gene that controls the traits determining the plant’s strength, height, and resistance to drought. If this gene is inserted into wheat, rice, or soybeans, it could produce a crop that is strong enough to survive a drought. This is an example of a GMO.  

Genetically modified organisms (GMO): 

GMOs are genetically modified organisms in which DNA from the desired organism is inserted into their DNA inside a laboratory. These are also known as transgenic organisms. GMOs are created by using methods like Recombinant DNA technology and Reproductive cloning. 

Genetic engineering can introduce improvements in crop plants, such as corn, wheat, and rice, and such crops whose genes are modified are called genetically modified crops. GMOs are created in order to increase the yield of the crop and to produce disease-resistant crops. 

Crops are modified in ways that increase productivity and nutrient content and are better able to resist disease, weeds, and harmful insects. This helps in reducing the need for pesticides and other potentially dangerous chemicals. 

Bt corn: 

Bt corn is an example of modern genetic engineering in agriculture. It is corn cultivated from cells that are injected with a bacterial gene that produces the Bt toxin Bt toxin is poisonous to insects and pests like the European corn borer, which destroys corn by digging through the stem and causing it to fall over.  

When the modified corn cells reproduce, the bacterial gene is part of the information that the corn cells pass on to their offspring.  

Other examples of genetically modified crops include: 

Golden Rice was genetically modified to generate beta-carotene twenty times more than the previous varieties of rice. Golden rice is intended for Asia. 

Another rice variety was also developed to fight iron deficiency. This was done by taking a gene from the bean plant and inserting it into the rice gene. The resultant rice helps to reduce iron deficiency. 

Flavr savor tomato is also an example of a GMO and was created to increase the shelf-life and fungal resistance of normal tomatoes. 

Animals like pigs, chickens, cows, fish, and mosquitoes are also genetically modified by scientists.  The embryo of such animals is genetically altered by the desired gene and the resulting animal produces more milk, and meat, prevents diseases, etc. Animals like mice, monkeys, pigs, etc. are also genetically engineered for scientific research. 

Cloning: 

Reproductive cloning involves the creation of an offspring that is identical to one of its parents. A clone is an organism that receives all of its DNA from one parent and is genetically identical to that parent. 

In 1996 Scottish scientist Ian Wilmut created a clone named Dolly by taking a body cell from an adult female sheep and transferring it to an egg with the nucleus removed. The egg was divided into a ball of cells as if it had been naturally fertilized, and it was placed inside a sheep to develop. The final result was a lamb nick named Dolly. Dolly’s DNA was identical to the DNA of the adult sheep from which the body cell was taken. 

Advantages and disadvantages of Genetic Modification: 

Summary:

• Genetic engineering, also known as genetic modification, is the process by which
  alterations are made in the genome of an organism and was discovered in 1973.
• Genetic engineering is done by replacing one base pair (A-T or C-G), deleting an entire
  section of DNA, or introducing an extra copy of a gene.
• Genetic engineering uses recombinant DNA technology to produce genetically modified
  organisms. Recombinant DNA is made by taking a useful segment of DNA from one
  organism and inserting it into another organism.
• Insulin is the first genetically engineered medicine created by inserting a gene from the
  intestine of the pig into a bacterium.
• GMOs are genetically modified organisms in which DNA from the desired organism is
  inserted into their DNA inside a laboratory. These are also known as transgenic
  organisms.
• GMOs are created by using methods like Recombinant DNA technology and Reproductive
  cloning.
• Genetic engineering can introduce improvements in crop plants, such as corn, wheat, and
  rice, and such crops whose genes are modified are called genetically modified crops.
• GMOs are created in order to increase the yield of the crop and to produce disease-
  resistant crops.
• Reproductive cloning involves the creation of an offspring that is identical to one of its
  parents. A clone is an organism that receives all of its DNA from one parent and is
  genetically identical to that parent.