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The NCERT Solutions for Class 12 Biology Chapter 9 Biotechnology Principles and Processes is an important chapter that discusses the principles and methods applied to genetic engineering as well as microbial biotechnology. It also includes topics like recombinant DNA technology, restriction enzymes, cloning vectors, PCR, and bioprocess engineering. The NCERT Solutions include answers to all the questions in a clear language that allows students to understand the difficult and complex topics easily, which helps in better learning and improves exam preparation.
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NCERT Exemplar for Class 12 Biology Biotechnology Principles and Processes
After going through the solutions of Biotechnology: Principles and Processes, students must be able to understand all the answers to the following questions:
Given below are the detailed answers to all the questions included in the Biotechnology: Principles and Processes chapter.
Answer:
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 blood clots |
3. | Insulin | To treat type I diabetes mellitus |
4. | Interferon α | 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 |
Answer:
The following chart shows the action of the restriction enzyme EcoRI, the substrate DNA on which it acts and the site where it cuts
Q3. What would be the molar concentration of human DNA in a human cell? Consult your teacher.
Answer:
The molar concentration of DNA in a human cell will be the total no. of chromosomes multiplied by 6.023 × 1023
Hence, the molar concentration of DNA in each diploid cell in humans is 46 × 6.023 × 1023 = 2.77×1025 moles
Q4. Do eukaryotic cells have restriction endonucleases? Justify your answer.
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.
Answer:
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.
Answer:
Palindromic sequences in the DNA molecule refer to groups of bases forming the same sequence when read either backwardly or forwardly. The recognition sites of restriction endonucleases are palindromic sequences. Five examples of palindromic DNA sequences are given below
1. ACTAGT/TGATCA
2. AAGCTT/TTCGAA
3. GGATCC/CCTAGG
4. AGGCCT/TCCGGA
5. ACGCGT/TGCGCA
Q7. Can you recall meiosis and indicate at what stage a recombinant DNA is made?
Answer:
In meiosis, during the pachytene stage of Prophase I, crossing-over takes place and recombinant DNA is formed by combining portions of male and female DNA.
Answer:
In recombinant DNA technology, the selection of transformed and non-transformed cells can be done using reporter genes that encode 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, the Lac Z gene, which codes for the 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 catalysis 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, a reporter enzyme can be used to monitor the transformation of host cells by foreign DNA in addition to a selectable marker.
Q9. Describe briefly the following:
Answer:
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 sequences.
Answer:
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 simply stirred tank bioreactors or sparged tank bioreactors.
Answer:
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 testing.
Q10. Explain briefly :
Answer:
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 temperatures.
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 the Taq polymerase enzyme and the cycle is repeated several times to obtain the desired number of copies.
(b) Restriction enzymes and DNA
Answer:
Restriction enzymes and DNA- Restriction enzymes are those enzymes which cut DNA at particular places. The restriction enzyme first scans the DNA template and looks for its recognition site. Once it finds the recognition site, it binds at that region of DNA and cuts each of the two strands in its sugar-phosphate backbone. The sites at which restriction enzymes cut DNA are called recognition sites of DNA. These are palindromic sequences i.e. they read similarly from the backward and forward direction.
Answer:
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.
Q11. Discuss with your teacher and find out how to distinguish between
(a) Plasmid DNA and Chromosomal DNA
Answer:
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. |
Answer:
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 more stable than RNA |
(c) Exonuclease and Endonuclease
Answer:
The differences between exonuclease and endonuclease are as follows:
Exonuclease | Endonuclease |
These are nucleases (enzymes) that cut DNA from its ends. | These are nucleases that cut DNA from internal sites on DNA |
NCERT Solutions for Class 12- Subject-wise
Given below are the steps which students can follow to solve the questions of the Biotechnology: Principles and Processes chapter effectively.
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Question: Among the following statements, carefully identify the ones that contain incorrect information about the palindromic sequences.
A. Palindromic sequences are DNA sequences that read the same in both directions but have an antiparallel orientation.
B. Palindromic sequences are DNA sequences that read the same in both directions but have a parallel orientation.
C. Palindromic sequences are recognised by a specific restriction endonuclease, leading to specific cleavage.
D. Palindromic sequences are recognised by exonucleases, resulting in non-specific cleavage.
Choose the option(s) that contain incorrect statements:
Options:
A and C
A and D
B and C
B and D
Answer: The correct answer is option (4).
Explanation:
Statement B states that the Palindromic sequences are DNA sequences that read the same in both directions but have a parallel orientation. This statement is incorrect. Palindromic sequences have an antiparallel orientation, not a parallel one. Therefore, statement B is incorrect.
Statement D states that the palindromic sequences are recognized by exonucleases, resulting in non-specific cleavage. This statement is incorrect. Exonucleases degrade DNA from the ends, but they do not specifically recognize and cleave palindromic sequences. Therefore, statement D is incorrect.
Hence, the correct statements are B and D.
NCERT Exemplar Class 12 Solutions
Here is a table for all the important topics from the chapter:
Below mentioned are the Chapterwise solutions:
The important topics of NCERT Solutions for Class 12 Biology Chapter 9 are
Yes, NCERT Solutions for Class 12 Biology Chapter 9 provide solutions for all questions given in NCERT Textbook Biology for Class 12. The majority of the board exam questions are taken from these exercises. Students who master these ideas will perform well in their final exams.
Multiple alleles are the occurrence of more than two alternative forms of a gene at one locus, for example, the ABO blood group system in human beings. Co-dominance is when both alleles in a heterozygous state are expressed to the full without one being dominant to the other, for example, in the AB blood group where A and B alleles are equally expressed.
Recombinant DNA technology in biotechnology entails the joining of genetic material from two or more sources to form altered DNA. It is achieved through the isolation of a desired gene, placing it into a vector (such as a plasmid), and inserting it into a host cell. The host cell makes copies, which results in the desired protein or characteristic. It finds application in medicine, agriculture, and industry.
Restriction enzymes are proteins that cut DNA at precise sequences, working as molecular scissors. They are pivotal in genetic engineering since they facilitate the precise cutting and manipulation of DNA fragments. Researchers utilize them to insert, delete, or alter genes in organisms. This method is important for cloning, gene therapy, and recombinant DNA technology.
Plasmids act as vectors in recombinant DNA technology by carrying foreign genes into host cells for expression. They are small, self-replicating DNA molecules that can integrate target genes using restriction enzymes and DNA ligase. Once introduced into a host (usually bacteria) via transformation, they replicate independently, ensuring gene propagation. Selectable markers (e.g., antibiotic resistance) help identify successfully modified cells.
Biotechnology significantly contributes to medicine by facilitating genetic modification, drug discovery, and targeted treatments. In agriculture, it increases crop yield, resistance to pests, and climate resilience with genetically modified organisms (GMOs). It also supports sustainable agriculture by minimizing chemical application. Biotechnology generally enhances health and food security across the world.
Changing from the CBSE board to the Odisha CHSE in Class 12 is generally difficult and often not ideal due to differences in syllabi and examination structures. Most boards, including Odisha CHSE , do not recommend switching in the final year of schooling. It is crucial to consult both CBSE and Odisha CHSE authorities for specific policies, but making such a change earlier is advisable to prevent academic complications.
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