NCERT solutions for class 12 biology chapter 11 biotechnology principles and processes: Biotechnology is a field which deals with the combination of biology and technology. The techniques of using live organisms or enzymes taken from organisms to produce products and processes which are useful to humans. For example: making curd, bread or wine, which are all microbe-mediated processes. It could also be thought of as a form of biotechnology. CBSE NCERT solutions for class 12 biology chapter 11 biotechnology principles and processes will provide you with all the answers of questions mentioned in this chapter. Likewise, so many other processes/techniques are also included under the process of biotechnology. For example, in vitro fertilisation leading to a ‘test-tube’ baby, synthesizing a gene and using it, developing a DNA vaccine or correcting a defective gene, are all part of biotechnology. Solutions of NCERT class 12 biology chapter 11 biotechnology principles and processes will make learning easier for you. In this chapter, you will also study the different processes of biotechnology. If you are looking for the answers of any other class from 6-12 then NCERT solutions are there for you.
Important topics of NCERT solutions for class 12 biology chapter 11 biotechnology principles and processes:
11.1 Principles of Biotechnology
11.2 Tools of Recombinant DNA Technology
11.2.1 Restriction Enzymes
11.2.2 Cloning Vectors
11.2.3 Competent Host (For Transformation with Recombinant DNA)
11.3 Processes of Recombinant DNA Technology
11.3.1 Isolation of the Genetic Material (DNA)
11.3.2 Cutting of DNA at Specific Locations
11.3.3 Amplification of Gene of Interest using PCR
11.3.4 Insertion of Recombinant DNA into the Host Cell/Organism
11.3.5 Obtaining the Foreign Gene Product
11.3.6 Downstream Processing
NCERT Solutions for Class 12 Biology Chapter 11 Biotechnology Principles and Processes - Solved Exercise Questions
Q1. Can you list 10 recombinant proteins which are used in medical practice? Find out where they are used as therapeutics (use the internet).
Recombinant proteins are proteins produced as a result of recombinant DNA technology. In this technology, there is the transfer of some specific gene from one organism to another by using molecular tools such as biological vectors, restriction enzymes etc. Some of the proteins produced through RDT and are being used for therapeutic uses are as follows:
| S.No || Name of the recombinant protein || Therapeutic use of the recombinant protein |
| 1. || DNAase I || To treat cystic fibrosis |
| 2. || Antithrombin III || To prevent the formation of the blood clot |
| 3. || Insulin || To treat type I diabetes mellitus |
| 4. || Interferon || Used for chronic hepatitis C |
| 5. || Interferon AZA || Used for herpes and virus enteritis |
| 6. || Coagulation factor VIII || To treat haemophilia A |
| 7. || Coagulation factor IX || To treat haemophilia B |
| 8. || Interferon B || To treat multiple sclerosis |
| 9. || Human growth hormone recombinant || To promote growth in humans |
| 10. || Tissue plasminogen activator || To treat the myocardial infection |
Q5. Do eukaryotic cells have restriction endonucleases? Justify your answer.
No, eukaryotic cells do not possess restriction enzymes. All the restriction endonucleases have been developed and isolated from different strains of bacteria. The bacteria possess these restriction endonucleases as a defence mechanism to restrict the growth of viruses. Their own DNA remain safe from these enzymes because it is methylated. The eukaryotic cell has RNA interference as a defence mechanism against foreign DNA. Thus, eukaryotic cells do not have restriction endonucleases.
Q6. Besides better aeration and mixing properties, what other advantages do stirred tank bioreactors have over shake flasks?
The advantages of stirred tank bioreactors over shake flasks are as follows:
1. Stirred tank bioreactors are utilised for large-scale production of biotechnological products, unlike the shake flask method which is used for small-scale production of products.
2. In stirred tank bioreactors, a small sample can be taken out for testing.
3. Stirred tank bioreactors have foam breakers to control the foam.
4. Stirred tank bioreactors have temperature and pH control systems.
Q9. Can you think and answer how a reporter enzyme can be used to monitor transformation of host cells by foreign DNA in addition to a selectable marker?
In recombinant DNA technology selection of transformed and non transformed cells can be done using reporter genes that encode for reporter enzymes. During the RDT experiment, the foreign gene is joined with a reporter gene. The reporter gene should be such that it produces a visible expression. For example, Lac Z gene which codes for enzyme beta-galactosidase is used as a reporter gene. The activity of this gene is not found in transformed cells as the product formed by its catalysation is not formed in transformed cells and bacterial colonies appear white. In non-transformed cells, this gene shows its activity and the catalysed product is formed, as a result of this, bacterial colonies appear blue. Thus, reporter enzyme can be used to monitor the transformation of host cells by foreign DNA in addition to a selectable marker.
Q10. Describe briefly the following: (a) Origin of replication
Origin of replication- This refers to the DNA sequence, from where replication of DNA starts. By linking a DNA sequence with the origin of replication, it can be allowed to replicate in the host cells. Origin of replication also controls the copy number of linked DNA sequence.
Bioreactors - These are large vessels (100-1000 litres) that are used for large-scale production of biotechnological products such as proteins, enzymes etc. from raw materials. In a bioreactor, optimum conditions such as temperature, pH, vitamins, oxygen, salts etc. are maintained. Stirred bioreactors are the most commonly used bioreactors. Stirred bioreactors can be simple stirred tank bioreactors or sparged tank bioreactors.
NCERT solutions for class 12 biology chapter 11 biotechnology principles and processes
(c) Downstream processing
Downstream processing- The process of separation and purification of biotechnological products is called downstream processing. The processes in downstream processing vary depending on the quality of the product. Before the release of the product, it undergoes clinical trials and quality control testings.
Q11. Explain briefly : (a) PCR
Polymerase Chain Reaction (PCR)- The molecular technique to amplify a gene and obtain its several copies is referred to as PCR. The process of PCR has certain requirements i.e. a thermostable enzyme called Taq polymerase ( obtained from Thermus aquaticus ), primers ( short stretches of DNA ), dNTPs, a template strand etc. The process of PCR takes place in three steps.
1. Denaturation- The double-stranded DNA helix is opened up by breaking their H-bonds at high temperature.
2. Annealing- The primers are allowed to hybridise to complementary regions of DNA. This step takes place at 45-55 C temperature.
3. Extension- The primers are extended with the help of Taq polymerase enzyme and the cycle is repeated several times to obtain the desired number of copies.
(b) Restriction enzymes and DNA
Restriction enzymes and DNA- Restriction enzymes are those enzymes which cut DNA at particular places. Restriction enzyme first scans the DNA template and look for its recognition site. Once it finds the recognition site, it binds at that region of DNA and cut each of the two strands in their sugar-phosphate backbone. The sites at which restriction enzymes cut DNA are called as recognition sites of DNA. These are palindromic sequences i.e. they read similar from the backward and forward direction.
Chitinase - The enzyme that catalyses the breakdown of chitin polysaccharide which is usually found in the cell wall of fungi. Chitinase is mainly used during DNA isolation from fungi.
Q12. Discuss with your teacher and find out how to distinguish between
(a) Plasmid DNA and Chromosomal DNA
The differences between plasmid DNA and chromosomal DNA are as follows:
| Plasmid DNA || Chromosomal DNA |
| Circular, extra-chromosomal DNA which is capable of self-replication and is found in bacteria is called plasmid DNA. || The entire DNA (excluding extrachromosomal DNA) present in the cell constitutes chromosomal DNA |
| It is found only in bacteria || IT is found in both bacteria and other eukaryotic cells. |
(b) RNA and DNA
The differences between RNA and DNA are as follows:
| RNA || DNA |
| RNA contains ribose sugar || DNA contains deoxyribose sugar |
| In RNA, adenine and uracil are found as pyrimidines || In DNA, adenine and uracil are found as pyrimidines |
| It has catalytic properties and is less stable than DNA || DNA is non-catalytic and is stable than RNA |
(c) Exonuclease and Endonuclease
The differences between exonuclease and endonuclease are as follows:
| Exonuclease || Endonuclease |
| These are nuclease (enzymes) that cut DNA from its ends. || These are nucleases that cut DNA from internal sites on DNA |
In NCERT solutions for class 12 biology chapter 11 biotechnology principles and processes and marketing of products and processes using live organisms, cells or enzymes. Modern biotechnology using genetically modified organisms was made possible only when man learned to alter the chemistry of DNA and construct recombinant DNA. This process of combination is called recombinant DNA technology or genetic engineering. This process includes the use of these things: restriction endonucleases, DNA ligase, appropriate plasmid or viral vectors to isolate the foreign DNA into the host organisms. And for large scale production bioreactors are being used.
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