Gene Technology/ Genetic Engineering-2

 

Process of Genetic Engineering

  • It is the process of altering the DNA in an organism’s genome. It refers to the direct manipulation of the organism’s characteristics in a particular way.

    • It involves changing one base pair (A-T or C-G), deleting a whole region of DNA, or introducing an additional 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 Technology 

  • It is the joining together of DNA molecules from two different species. The recombined DNA molecule is inserted into a host organism to produce new genetic combinations that are of value to science, medicine, agriculture, and industry. 

    • The focus of all genetics is the gene, the fundamental goal of laboratory geneticists is to isolate, characterize, and manipulate genes.

    • The technology is based primarily on two other technologies, cloning and DNA sequencing.


Cloning 

  • Cloning is the process of generating a genetically identical copy of a cell or an organism. Cloning happens often in nature. Genes, cells, tissues, and even whole animals can all be cloned.

    • For example, when a cell replicates itself asexually without any genetic alteration or recombination.

  • Animals are cloned in one of two ways:

    • The first method is called embryo twinning. Scientists first split an embryo in half. Those two halves are then placed in a mother’s uterus. Each part of the embryo develops into a unique animal, and the two animals share the same genes. 

    • The second method is called somatic cell nuclear transfer. Somatic cells are all the cells that make up an organism, but that are not sperm or egg cells.

      • Sperm and egg cells contain only one set of chromosomes, and when they join during fertilization, the mother’s chromosomes merge with the father’s. Somatic cells, on the other hand, already contain two full sets of chromosomes. 

        • To make a clone, scientists transfer the DNA from an animal’s somatic cell into an egg cell that has had its nucleus and DNA removed. The egg develops into an embryo that contains the same genes as the cell donor. Then the embryo is implanted into an adult female’s uterus to grow.

    • Cloning of an animal was successfully performed for the first time by Ian Wilmut and his colleagues at the Roslin Institute in Edinburgh, Scotland.

      • They cloned a sheep named Dolly. Dolly was born in 1996 and was the first mammal to be cloned.

DNA Sequencing

  • The technique used to determine the nucleotide sequence of DNA (deoxyribonucleic acid). The nucleotide sequence is the most fundamental level of knowledge of a gene or genome. 

  • It is the blueprint that contains the instructions for building an organism, and no understanding of genetic function or evolution could be complete without obtaining this information.

DNA


Transgenic Animals

  • Transgenic means that one or more DNA sequences from another species have been introduced by artificial means. Organisms that have altered genomes are known as transgenic. Most transgenic organisms are generated in the laboratory for research purposes.

    • Animals usually are made transgenic by having a small sequence of foreign DNA injected into a fertilized egg or developing embryo. For exp: knock-out mice.

    • Transgenic plants can be made by introducing foreign DNA into a variety of different tissues. (e.g., golden rice, cotton, rice, maize, potato, tomato, brinjal, cauliflowers, cabbage, etc.) 


Gene Therapy

  • Gene therapy aims to treat/cure/prevent disease by replacing a defective gene with a normal one using recombinant DNA technology.

    • It is a collection of methods that allows correction of a gene defect that has been diagnosed in a child/embryo.

    • Correction of a genetic defect involves delivery of a normal gene into the individual or embryo to take over the function of and compensate for the non-functional gene.

  • The first clinical gene therapy was given in 1990 to a 4-year old girl with adenosine deaminase (ADA) This enzyme is crucial for the immune system to function.

  • It can provide potential treatment of diseases caused by recessive gene disorders (cystic fibrosis, hemophilia, muscular dystrophy, and sickle cell anemia), acquired genetic diseases such as cancer, and certain viral infections, such as AIDS.

CRISPR-Cas9 Technology

  • CRISPR: It is a specialized region of DNA with two distinct characteristics: the presence of nucleotide repeats and spacers. 

    • Repeated sequences of nucleotides (the building blocks of DNA) are distributed throughout a CRISPR region. 

    • Spacers are bits of DNA that are interspersed among these repeated sequences.

  • Technology: It is a simple yet powerful tool for editing genomes. It allows researchers to easily alter DNA sequences and modify gene function. 

    • It replicates natural defence mechanisms in bacteria to fight virus attacks, using a special protein called Cas9.

      • Cas9 Protein: It is an enzyme that cuts foreign DNA. The protein typically binds to two RNA molecules: crRNA and another called tracrRNA (or "trans-activating crRNA"). The two then guide Cas9 to the target site where it will make its cut. 

  • Mechanism: CRISPR-Cas9 technology behaves like a cut-and-paste mechanism on DNA strands that contain genetic information. 

    • The specific location of the genetic codes that need to be changed, or edited, is identified on the DNA strand, and then, using the Cas9 protein, which acts like a pair of scissors, that location is cut off from the strand.

    • A DNA strand, when broken, has a natural tendency to repair itself. Scientists intervene during this auto-repair process, supplying the desired sequence of genetic codes that binds itself with the broken DNA strand.

  • Its many potential applications include correcting genetic defects, treating and preventing the spread of diseases and improving crops.

Nobel Prize, 2020

  • The Nobel Prize in Chemistry for 2020 was given to two women scientists namely Emmanuelle Charpentier (France) & Jennifer A. Doudna (Germany). 

  • The nobel prize was given to them for the development of a method for genome editing.

  • The two scientists have pioneered the use of CRISPR (Clustered Regularly Interspaced Short Palindromic Repeats) – Cas9 (CRISPR-associated protein 9) system as a gene-editing tool.

  • Using components of the CRISPR system, researchers can add, remove, or even alter specific DNA. This has led to a significant impact in biology, medicine, and agriculture.

Comments

Post a Comment

Popular posts from this blog

Vaccine Nationalism

Image
What is vaccine nationalism? When a country manages to secure doses of vaccines for its own citizens or residents and prioritises its own domestic markets before they are made available in other countries it is known as ‘vaccine nationalism’ .  This is done through pre-purchase agreements between a government and a vaccine manufacturer. For example , the United States, the United Kingdom, Japan, and the European Union have spent tens of billions of dollars on deals with vaccine front runners such as Pfizer Inc, Johnson & Johnson and AstraZeneca Plc even before their effectiveness is proven. Pre-purchase agreements: It is an agreement where, even before the end of final stage human trials or regulatory approval, several wealthier countries enter into pre-purchase agreements with vaccine manufacturers. History of Vaccine Nationalism The process of hoarding vaccines can be traced back to a similar situation that happened in 2009 during the H1N1 flu pandemic. Australia, the first ...
Read more

Mystery Disease in Andhra Pradesh

Image
A ‘mystery disease’ has emerged in Eluru, Andhra Pradesh. It has caused illness to almost 450 people and few deaths also. It is believed that organochlorines are responsible for this mysterious disease. The symptoms like seizures, nausea, dizziness and headaches are seen among patients. Heavy metals like Lead and nickel content in drinking water and milk was primarily established as the root cause of the disease. It is found in the blood sample of patients. What are Organochlorines? Organochlorines (OC) are a group of chlorinated compounds that belong to the class of persistent organic pollutants (POPs) with high persistence in the environment. They are widely used as pesticides. Applications : OC insecticides were earlier used to control malaria and typhus; they were later banned in most countries.  They are relatively cheaper; as a result Dichlorodiphenyltrichloroethane (DDT), hexachlorocyclohexane (HCH), aldrin and dieldrin are among the most widely used pesticides...
Read more

What is Contour Bunding?

Image
Contour Bunding involves the placement of lines of stones along the natural rises of a landscape, and Contour farming. These techniques help to capture and hold rainfall before it can become runoff. They also inhibit wind erosion by keeping the soil. Contour bunds is a traditional low-cost method of soil conservation suitable for sloping land; it promotes water retention and helps prevent erosion. Contour bunding is a proven sustainable land management practice for marginal, sloping, and hilly land where the soil productivity is very low. Contour farming is used on sloping land where crops are grown. Contour farming is most effective on slopes between 2 and 10 percent.
Read more