Biotechnology Principles and Processes ncert solutions: Class 12th biology chapter 9 ncert solutions
Textbook | NCERT |
Class | Class 12 |
Subject | Biology |
Chapter | Chapter 9 |
Chapter Name | Biotechnology Principles and Processes class 12 ncert solutions |
Category | Ncert Solutions |
Medium | English |
Are you looking for Ncert Solutions for Class 12 Biology Chapter 9 Biotechnology Principles and Processes? Now you can download Ncert class 12 biology chapter 9 questions and answers pdf from here.
Question 1: Can you list 10 recombinant proteins which are used in medical practice? Find out where they are used as therapeutics (use the internet).
Solution 1: Recombinant proteins are obtained from the recombinant DNA technology. This technology involves the transfer of specific genes from an organism into another organism using vectors and restriction enzymes as molecular tools.
Listed below are 10 recombinant proteins.
Recombinant protein | Therapeutic application |
Interferon-α | In the treatment of chronic hepatitis C |
Insulin | In the treatment of type I diabetes mellitus |
Interferon-β | Use to treat herpes and viral enteritis |
Interferon B | In the treatment of Multiple Sclerosis |
Anti-thrombin III | Blood-clot prevention |
Human recombinant growth hormone | To promote growth in an individual |
Coagulation factor VIII | In the treatment of haemophilia A |
Coagulation factor IX | In the treatment of haemophilia B |
DNAase I | In the treatment of cystic fibrosis |
Tissue plasminogen activator | In the treatment of acute myocardial infection |
Question 2: Make a chart (with diagrammatic representation) showing a restriction enzyme, the substrate DNA on which it acts, the site at which it cuts DNA and the product it produces.
Solution 2: Name of the Restriction enzyme – Bam HI.
The substrate DNA on which it acts –
Question 3: From what you have learnt, can you tell whether enzymes are bigger or DNA is bigger in molecular size? How did you know?
Solution 3: Enzymes are smaller in size than DNA molecules. This is because DNA contains genetic information for the development and functioning of all living organisms. It contains instructions for the synthesis of proteins and DNA molecules. On the other hand, enzymes are proteins which are synthesised from a small stretch of DNA known as ‘genes’, which are involved in the production of the polypeptide chain.
Question 4: What would be the molar concentration of human DNA in a human cell? Consult your teacher.
Solution 4: The molar concentration of human DNA in a human cell can be given as
⇒ 6.023 x 1023 x Total number of chromosomes
⇒ 6.023 x 1023 x 46
⇒ 2.77 x 1023 moles
Therefore, 2.77 x 1023 moles is the molar concentration of DNA in each of the diploid cells in humans.
Question 5: Do eukaryotic cells have restriction endonucleases? Justify your answer.
Solution 5: No, eukaryotic cells do not have restriction endonucleases. This is because the DNA of eukaryotes is highly methylated by a modification enzyme, called methylase. Methylation protects the DNA from the activity of restriction enzymes .These enzymes are present in prokaryotic cells where they help prevent the invasion of DNA by virus.
Question 6: Besides better aeration and mixing properties, what other advantages do stirred tank bioreactors have over shake flasks?
Solution 6: The shake flask method is used for a small-scale production of biotechnological products in a laboratory. whereas stirred tank bioreactors are used for a large-scale production of biotechnology products. Stirred tank bioreactors have several advantages over shake flasks:
- (i) Small volumes of culture can be taken out from the reactor for testing.
- (ii) It has a foam breaker for regulating the foam.
- (iii) It has a control system that regulates the temperature and pH.
Question 7: Collect 5 examples of palindromic DNA sequences by consulting your teacher. Better try to create a palindromic sequence by following base-pair rules.
Solution 7: The palindromic sequence is a certain sequence of the DNA that reads the same whether read from 5’ → 3’ direction or from 3’→ 5’ direction. They are the site for the action of restriction enzymes. Most restriction enzymes are palindromic sequences. Five examples of palindromic DNA sequences are as follows:
(i) 5′-—————GGATCC——————3’
3′—————CCTAGG—————–5′
(ii) 5’—————AAGCTT——————3′
3′——————TTCGAA —————-5′
(iii) 5′—————–ACGCGT—————–3′
3′——————TGCGGA————– 5′
(iv) 5′———- ACTAGT————3′
3′——————TGATCA————5′
(v) 5′—————AGGCCT—————3′
3′——————TCCGGA————–5′
Question 8: Can you recall meiosis and indicate at what stage a recombinant DNA is made?
Solution 8: Meiosis is a process that involves the reduction in the amount of genetic material. It is two types, namely meiosis I and meiosis II. During the pachytene stage of prophase I, crossing over of chromosomes takes place where the exchange of segments between non-sister chromatids of homlogous chromosomes takes place. This results in the formation of recombinant DNA.
Question 9: 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?
Solution 9: To monitor the transformation of host cells by foreign DNA, a reporter gene can be used. They serve as a selectable marker to find out if the host cell has used up the foreign DNA else the foreign gene is expressed in the cell. The reporter gene and the foreign gene are placed by scientists in the same DNA construct.
This collective DNA construct is introduced into the cell, where the reporter gene is used as a selectable marker to discover the successful uptake of foreign genes or the genes of interest. In a jellyfish, the lac Z gene is an example of a reporter gene that encodes for a green fluorescent protein.
Question 10: Describe briefly the following:
(a) Origin of replication
(b) Bioreactors
(c) Downstream processing
Solution 10: (a) Origin of Replication: This is a sequence from where replication starts and any piece of DNA when linked to this sequence can be made to replicate within the host cells. This sequence is also responsible for controlling the copy number of the linked DNA. So, if one wants to recover many copies of the target DNA it should be cloned in a vector whose origin support high copy number.
(b) Bioreactor: Bioreactors are large vessels used for the large-scale production of biotechnology products from raw materials. They provide optimal conditions to obtain the desired product by providing the optimum temperature, pH, vitamin, oxygen, etc. Bioreactors have an oxygen delivery system, a foam control system, a PH, a temperature control system, and a sampling port to obtain a small volume of culture for sampling.
(c) Downstream Processing : The product obtained is subjected to a series, of processes collectively called downstream processing before it is made into a finished product ready for marketing. The two main processes are separation and purification. The product is then formulated with suitable preservatives. Such formulations have to undergo clinical trials, in case of drugs.
Question 11: Explain briefly
(a) PCR
(b) Restriction enzymes and DNA
(c) Chitinase
Solution 11:
(a) PCR (Polymerase Chain Reaction)
PCR, or Polymerase Chain Reaction, is a molecular biology technique used to amplify specific DNA sequences. The process involves repeated cycles of denaturation (heating the DNA to separate the strands), annealing (cooling to allow primers to bind to the target DNA), and extension (using DNA polymerase to synthesize new DNA strands). This exponential amplification allows for the generation of millions of copies of a specific DNA segment, making it invaluable for applications like genetic testing, cloning, forensic analysis, and studying genetic material from various sources.
(b) Restriction Enzymes and DNA
Restriction enzymes, also known as restriction endonucleases, are proteins that recognize specific short sequences of DNA and cleave the DNA at or near those sites. They are naturally occurring in bacteria and serve as a defense mechanism against viral DNA. In molecular biology, these enzymes are used for various applications, such as cloning, where they facilitate the insertion of foreign DNA into plasmids by creating compatible ends for ligation. By cutting DNA at precise locations, restriction enzymes allow scientists to manipulate and study genes effectively.
(c) Chitinase
Chitinase is an enzyme that catalyzes the hydrolysis of chitin, a polysaccharide that constitutes the structural component of the exoskeletons of arthropods, cell walls of fungi, and certain algae. Chitinases are produced by various organisms, including bacteria, fungi, and plants, and play a crucial role in biological processes such as the degradation of chitin during molting in insects and the defense against fungal infections in plants. In biotechnology, chitinase has applications in agriculture, waste management, and the production of chitosan from chitin, which has various industrial uses.
Question 12: Discuss with your teacher and find out how to distinguish between
(a) Plasmid DNA and Chromosomal DNA
(b) RNA and DNA
(c) Exonuclease and Endonuclease
Solution 12: (a) Plasmid DNA and Chromosomal DNA
Plasmid DNA | Chromosomal DNA |
---|---|
Circular and small (1-200 kb) | Linear and large (millions of base pairs) |
Found mainly in bacteria and some eukaryotes as extra-chromosomal DNA | Contains the main genetic information of the organism |
Can replicate independently of the chromosomal DNA | Replicates during cell division as part of the cell cycle |
Often carries genes for antibiotic resistance or other adaptive traits | Contains essential genes necessary for the growth, development, and reproduction of an organism |
(b) RNA and DNA
RNA | DNA |
---|---|
Single-stranded molecule (generally) | Double-stranded molecule |
Contains ribose sugar | Contains deoxyribose sugar |
Uses uracil (U) as a nitrogenous base | Uses thymine (T) as a nitrogenous base |
Functions in protein synthesis and gene regulation (e.g., mRNA, tRNA, rRNA) | Stores genetic information in cells |
More reactive and less stable due to the 2′-OH group | More stable due to the absence of the 2′-OH group |
(c) Exonuclease and Endonuclease
Exonuclease | Endonuclease |
---|---|
Removes nucleotides from the ends of DNA or RNA strands | Cuts DNA or RNA at internal sites within the strand |
Works by cleaving nucleotides one at a time from the terminal end | Recognizes specific sequences or cuts randomly within the DNA strand |
Example: DNA polymerase with exonuclease activity (proofreading) | Example: Restriction enzymes like EcoRI |