Category: Biology Second Paper

In 1985 scientist Alec Jeffreys discovered the finger printing method. In 1986 this method was adopted separately.

Fingerprints, marks or marks on human hands are called tip signatures or finger prints. Identification of specific bands from highly variable regions of DNA with radioactive probes is called DNA fingerprinting. The complex process by which an individual can be distinguished from other individuals in genetic information by determining the arrangement of deoxyribonucleotides in DNA is called DNA fingerprinting. Due to variations in DNA (ATGC), every person in the world has a different fingerprint. Fingerprints are required for land registry, marriage certificate registry, biometric seam registration, school attendance confirmation, office staff attendance confirmation, any contract etc.

Polymerase Chain Reaction is abbreviated as PCR. PCR is the fastest cloning technique. When the DNA vector is isolated and introduced into the host cell, the desired gene is spliced ​​with the host and numerous copies are made. In 1984, American scientist Kary Mullis invented the PCR technique.
Step-1: First the desired piece of DNA is heated to 95 degrees C. It separates the DNA strands. As a result, the primers bind to the designated sites. This step is called Denaturing step.
Step-2: Very quickly the temperature of the process is brought down. Primers bind to DNA primers. However, the actual temperature may be lower or higher depending on the length and sequence of the primer. A reaction that occurs once is called a cycle.
Step-3: At this stage, the reaction temperature is 45 degrees Celsius. is kept at (dNTPs) In the presence of Mg2+ ions, nucleotides link together to form new complementary DNA strands.
Step-4: The resulting DNA molecules are separated again by heat. Primer-1 binds to the 5→3 primer and Primer-2 binds to the 3→5 primer. At the end of the second cycle, the two progenitors make two new DNAs. The number of DNA molecules in each cycle will double that of the previous cycle.
With a machine, the reactions that make DNA go one after the other. This device is called thermal cycler. Each step takes 2-5 minutes. The reaction is limited to 25-35 cycles. One molecule of DNA will produce 235(2n) = 3.5×1010 molecules of DNA after 35 cycles.

1. Selection and Isolation of Target DNA: Target DNA is selected for gene cloning. Selected cells are slightly lysed. Cell membranes are broken down using enzymes lysozyme (bacterial cells), chitinase (fungal cells), cellulase (plant cells). The lysed cells are then centrifuged into test tubes. An amount of cesium chloride solution is introduced into a centrifuge test tube. The solution is then centrifuged. As a result, a band of DNA is formed on the test tube. DNA is mixed with other components to form a homogenate. Other components are separated from homogenate DNA using enzymes like protease (protein), ribonuclease (RNA), amylase (sugar), lipase (fat). The purified DNA is then precipitated as a thread by immersing in a cold ethanol solution. The desired DNA segment is selected from the degraded DNA.
2. Carrier Selection: The carrier is selected to carry the required portion of the target DNA. In this case, the bacterium Agrobacterium tumefaciens acts as a good carrier. The desired DNA segments are attached to the plasmid DNA located in the cytoplasm of these bacteria. In some cases carriers such as cosmids, phagemids, artificial chromosomes etc. are used.
3. Excision of the target DNA at a specific location: Several sections are cut from the target DNA using restriction enzymes. Corresponding segments are also excised from the carrier plasmid DNA using the same enzyme. This process is called restriction digestion.
4. Preparation of recombinant DNA: The target DNA is ligated to the carrier plasmid DNA with the help of an enzyme called DNA ligase. Recombinant DNA is produced by ligation of the desired DNA with the carrier plasmid DNA.
5. Introduction of Recombinant DNA into the Host: The host is selected to carry the recombinant DNA. In this case E. coli bacteria act as host. Recombinant DNA is introduced into host cells. But under normal conditions bacteria do not accept other plasmids. If the culture medium in which the bacterium is grown is heated and a suitable environment is created by adding calcium, the bacterium takes up another plasmid. The process of introducing recombinant DNA into the bacterial body is called transformation.
6. Amplification or Cloning of Recombinant DNA: After the recombinant DNA is introduced into the host, the host bacteria are grown in culture medium. Within a short period of time, the bacteria multiply in the culture medium to produce thousands of copies. Recombinant DNA is also produced. Thus increasing the number of recombinant DNA is called gene cloning.

The word clone means exact copy. Multiple organisms with the same genotype are called clones. The process of making numerous identical copies of a particular gene (DNA) is called gene cloning. Dolly was born in 1997 by cloning a sheep.
Gene cloning can be done in two ways. Gene cloning by vector and gene cloning by PCR technology.

1. E. coli to produce insulin hormone. Bacteria are used. Insulin is used in diabetes.
2. Genetic engineering of E. coli bacteria is of immense importance.
3. Plasmid DNA is used to produce interferon.
4. Plasmid DNA plays an important role in gene cloning.
5. Transgenic cotton plants have been created in America using plasmid DNA.
6. Super rice has been created through biotechnology. Eating this paddy rice cures night blindness.
7. Flavor saver tomatoes have been created through biotechnology.
8. Recombinant DNA technology is creating healthy, vigorous and improved crop varieties.
9. At present, potato, apple, cotton, wheat etc. insect resistant plants have been developed.
10. The Nif gene was isolated from the nitrogen-fixing Rhizobium bacterium and inserted into the chromosomes of rice plants. This rice plant can fix nitrogen and does not require application of urea fertilizers.
11. Seedless fruits are being created around the world using recombinant DNA technology.
12. Application of herbicides on land causes extensive damage to crop plants. Transgenic plants have been created by separating the Bar gene from bacteria called Streptomyces and applying it to tomato, potato, and tobacco plants. These transgenic plants are not affected by herbicides.

1. Plasmids are widely used in molecular genetics research.
2. Plasmids serve as useful vectors in genetic engineering and gene cloning.
3. Plasmids have a role in producing high yielding crops.
4. Plasmids are used in biotechnology to produce disease resistant varieties.
5. Plasmids are used to make insulin, interferon, enzymes etc.
6. Plasmids have applications in the diagnosis of a variety of diseases.
7. Plasmids are used to create insect and weed resistant plants.

1. Single Copy Plasmid: If there is only one plasmid in the bacterial cell, it is called single copy plasmid.
2. Multicopy Plasmid: If there are many plasmids (1000) in the bacterial cell, it is called multicopy plasmid.

1. F and F^– Plasmids: Plasmids that transfer genetic material from one bacterial cell to another are called F plasmids. Plasmid which helps in sexual reproduction by forming pili in bacterial cells is called F © plasmid.
2. R Plasmid: Plasmids that contain antibiotic resistance genes are called R plasmids. R6 plasmid is resistant to 6 important antibiotics. It is a gene marker. It contains the tetracycline antibiotic resistance gene.
3. Col Plasmid: Plasmids that produce a toxic protein called colicin are called Col plasmids. Colicin can kill susceptible E. coli cells. Plasmids contain genes producing vibriocin. Vibriocin can kill susceptible Vibrio cholerae cells.
4. Virulence Plasmid: Plasmids that cause disease are called virulence plasmids. Ti plasmid of Agrobacterium tumefaciens causes crown gall disease in dicotyledonous plants.
5. Degradative Plasmids: Plasmids which can rapidly convert the abnormal substances of bacteria like toluene, salicylic acid etc. are called degradative plasmids.