Class 12 Biology Chapter 11 Biotechnology: Principles and Processes

Class 12 Biology Chapter 11 Biotechnology: Principles and Processes The answer to each chapter is provided in the list so that you can easily browse through different chapters Assam Board HS 2nd Year Biology Chapter 11 Biotechnology: Principles and Processes Question Answer.

Class 12 Biology Chapter 11 Biotechnology: Principles and Processes

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Also, you can read the SCERT book online in these sections Solutions by Expert Teachers as per SCERT (CBSE) Book guidelines. These solutions are part of SCERT All Subject Solutions. Here we have given Assam Board Class 12 Biology Chapter 11 Biotechnology: Principles and Processes Solutions for All Subjects, You can practice these here.

III. Short Questions 3 Marks : 

Q.1. State the basic steps involved in genetically modifying an organism. 

Ans : The following basic steps are involved in genetic modification of organisms. 

(i) Isolation of DNA. 

(ii) Fragmentation of DNA. 

(iii) Isolation of desired fragments of DNA. 

(iv) Joining of DNA fragments into vector. 

(v) Transferring recombined DNA into host. 

(vi) Culturing of host cells for multiplication of recombined DNA. 

Q.2. Name the specific enzymes used to break the cells of organisms like bacteria, eukaryotic płant and fungus and release DNA along with other macromolecules. 

Ans :   

 3. Distinguish between : 

(i) Plasmid DNA and Chromosomal DNA. 

Ans : (a) Plasmid is the circular DNA while chromosomes are found in higher groups of organism as carrier of heredity.

(b) Plasmid is found in bacteria and plays great role in genetic engineering. 

(ii) Exonuclease and Endonuclease.

Ans : Exonuclease is an enzyme used to cut the DNA for the purpose of cloning while the endonuclease is termed as bio scissors. Both the enzymes are very useful in gene cloning. 

Q.4. What is meant by recognition sequence? Write the recognition site of EcoRI and where it cuts the DNA. 

Ans : Endonuclease cut DNA at specific point to separate certain sequence of base pair nucleotides. It therefore must recognise the Palindromic nucleotide sequence in DNA before cutting. The sequences are either 5 → 3 or 3 → 5 and may contain a few to they base pairs. 

There are 3 types of endonucleases – Type I, Type II and Type III which cut sequence at different base pairs. Of these the types II remarkable for their palindrome. They are also very stable. In palindrome, the base sequence such that if read from both end they appear to be same. 

5′ GAA ↑ AAG 3′                5° GAA ↑ AAG 3′ 

Single Stand DNA            Double Stranded DNA

(If read from right to left and left to right it will be the same sequence in both strands) 

In palindrome with rotational symmetry the base sequence in the first half of one strand DNA double helix is the mirror image of the second half of its complementary stand. Thus the base sequence in both the strands read the same when read from 5′- 3′ end and 3′-5′ end both sands. Thus recognition sequence of ECORI  are 

5′ →3′ or 3 → 5 the  

                      5′ GAA | TTC 3′ 

                      3′ CTT | AAG 5″ 

                      ECORI recognition site 

Q.5. What is downstream processing in respect of biotechnology? 

Ans : Any product made through biotechnology is not a finished product. It may have impurity, it may contain harmful by products also. So these need to be refined. The processes which purifies materials as finished products is called downstream process. Further, preservation and storing also need to be addressed appropriately. In case of pharmaceuticals clinical trials need to be carried out. The quality control measure is another area of downstream process. 

Q.6. Write the major steps involved in gene cloning. 

Ans : Genes are specific parts of DNA. For cloning specific gene, it must be separated from the DNA and then it should be attached with a vector like plasmid or bacteriophage DNA (vector are carriers). As the plasmid or the bacteriophage DNA multiplies within the bacteria or the bacteriophages the gene inserted in them also multiplies. For this purpose, the following methods are applied. 

(i) At first the plasmids DNA found in bacteria are brought out of the 6. bacterial cell by lysing the bacterial cell. The plasmid which is used to carry the gene to be cloned is also called passenger or vehicle DNA or Vector. In place plasmid, bacteriophage DNA can also be isolated and used as vector. 

(ii) In the next step, the gene to be isolated and cloned is identified in the DNA of another bacteria or organism and is bought out. 

(iii) Now using an enzyme called restriction endonuclease the specific part of the DNA carrying the specific gene is cut out. With the same enzyme the specific part of the plasmid where the gene will fit is opened by cut and the equivalent part of the plasmid is taken out so that the inserted gene fits will in the plasmid. The cut end of the plasm and the DNA well have sticky ends in one of their single strand. These sticky ends help them to join with their complementary parts. 

Q.7. Match the items of column A with the items of column B. 

Ans : 

Q.8. Give reasons of recombinant DNA formation from two sources of DNA. 

Ans : DNA recombination is done to add certain quality gene to the DNA by deleting some part of a DNA and adding another piece there taken from DNA of another organism. The inserted DNA piece must have specific nucleotide sequence that code for certain quality which is not thee in the host DNA. It is therefore a recombinant DNA carries DNA from host and doner. 

Q.9. State the principle underlying ‘gel electrophoresis’ and mention two applications of this technique in Biotechnology. 

Ans : The device uses a substance called agarose gel. Any substance having twɔ different fractions will move opposite to each other depending upon the electric charge. Some will move towards positive end and another will move towards negative end and thus both can be separated. This device is extensively used for separation of 

(i) DNA fraction done by endonuclease. The lighter fragment will move faster than heavier fragments and thus these can be collected separately. 

(ii) It is also extensively used in DNA fingerprinting in which various fractions of DNA are separated by this method. 

Q.10. Explain any three methods to force ‘alien’ or recombinant DNA into hosts cells.

Ans : Recombinant DNA is pushed into the host cell by any of the following methods : 

(i) Using plasmid vector such as Ti plasmid of Agrobacterium, K12 of E. coli etc. 

(ii) Using virus vector such as Lambda, M13 etc. 

(iii) Using a special device called gene gun. 

Q.11. What is Biotechnology? Discuss the principles of biotechnology. 

Ans : The term “biotechnology” was brought into popular usage in mid – 1970s as a result of increased potential for the application of the emerging techniques of molecular biology. Biotechnology is a fast growing applied science. According to definition adopted by European Federation of Biotechnology (1978) “Biotechnology makes it possible, through an integrated application of knowledge and techniques of biochemistry, microbiology, genetics and chemical engineering to draw benefit at the technological level from the properties and capacities of microorganisms and cell cultures.” 

                                 OR 

The integration of natural science and organisms, cells, parts there of and molecular analogies for products and services is called biotechnology. The term biotechnology was used by Leeds City council (1920) when an institute in biotechnology was set up. We find its applications in even back to 5000 years with the discovery of the production of alcoholic beverages by fermentation. Biotechnology today is undergoing a resurgence in the wide range of applications and the tremendous increasè all over the world. Biotechnology is the application of scientific and engineering principles to the processing of materials by biological agents to provide goods and services. 

Principles of biotechnology : 

(i) Genetic engineering : The ability to isolate a gene coding for desired product and transfer it to another organism has opened the way either to the more effective production of useful proteins or to the introduction of novel characteristics in the host organism. Thus, this refers to methods to change the chemical structure of genetic material i.e. DNA and RNA and then to introduce into host and alter its phenotype. 

(ii) To maintain the microbial contamination free (sterile) ambience in (11). chemical engineering. Due to such type maintenance only desired microbe/ cells will be formed in huge number for manufacture of biotechnological- products like hormones vaccines, blood clotting factors, antibiotics steroids, enzymes etc. It is necessary to have complete aseptic condition. 

Q.12. Expand the term PCR. Write the principle of PCR. 

Ans : PCR technique was developed by Kary Mullis 1985. If one knows the sequence of at least part of a DNA segment to be cloned, a number or copies of that DNA segment can be hugely amplified using polymerase chain reaction. It is able to generate microgram quantities of DNA copies (up to billion copies) of desired DNA segment, present even as a single copy with short time. 

The technique is based on principle that when a DNA molecule is subjected to high temperature due to denaturation the two DNA strands separate. As a result two single stranded DNA molecules appear. 

Q.13. Explain the process by which a bacterial cell can be made ‘competent’ in recombinant DNA technology. 

Ans : The ligated plasmid mixture is introduced into the bacterial cells where they takeup DNA through transformation process. Transformation iş generally carried out by placing activity glowing cells of a bacterium in cold, dilute solution of CaCIP which enhances the ability of bacterial cells to take up foreign DNA. In majority of the cases, E coli is the most preferred host because: 

(i) Molecular biology of the bacteria is well understood. 

(ii) CaC12 treated cells are highly transformable.

(iii) E-coli transcribes and translates most gram + ve and Gram – ve guess except some actinomycetes genes There are many methods to introduce the ligated DNA into recipient competent alls.

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