Biotechnology principles and process class 12 Chapter 11

Biotechnology: Principles and Process class 12 NCERT Chapter 11

Biotechnology Principles and Process class 12 taken from NCERT Book Chapter 11 All the Important Topics are covered related to this chapter read carefully and clear your all doubts.

Biotechnology Principle and Process Class 12
Biotechnology Principle and Process Class 12 Introduction

In Class 12 Biotechnology, we learn about the fundamental principles and processes involved in biotechnology.

This includes understanding how living organisms, like plants and animals, can be used to create useful products or solve problems. We explore how scientists manipulate biological systems to develop medicines, improve agriculture, and address environmental issues

Biotechnology Principle and Process class 12
  1. Tools and Techniques:
    • Genetic engineering involves manipulating an organism’s genetic material to achieve desired traits.
    • Techniques include DNA isolation, restriction enzymes to cut DNA, and DNA ligases to join DNA fragments.
  2. Recombinant DNA Technology:
    • Recombinant DNA is formed by combining DNA from different sources.
    • It allows the creation of genetically modified organisms (GMOs) with desirable traits, like pest resistance in crops.
  3. Cloning:
    • Cloning produces identical copies of genes, cells, or organisms.
    • Dolly the sheep was the first mammal cloned from an adult somatic cell.
  4. DNA Fingerprinting:
    • DNA fingerprinting is used to identify individuals based on unique patterns in their DNA.
Biotechnology Principle and Process class 12 Author

Herbert Boyer was born in 1936 and brought up in a corner of western Pennsylvania where railroads and mines were the destiny of most young men. He completed graduate work at the University of Pittsburgh, in 1963, followed by three years of post-graduate studies at Yale. In 1966, Boyer took over an assistant professorship at the University of California at San

Francisco. By 1969, he performed studies on a couple of restriction enzymes of the E. coli bacterium with especially useful properties. Boyer observed that these enzymes have the capability of cutting DNA strands in a particular fashion, which left what has become known as ‘sticky ends’ on the strands. These clipped ends made pasting together pieces of DNA a precise exercise.

This discovery, in turn, led to a rich and rewarding conversation in Hawaii with a Stanford scientist named Stanley Cohen. Cohen had been studying small ringlets of DNA called plasmids and which float about freely in the cytoplasm of certain bacterial cells and replicate independently from the coding strand of DNA.

Cohen had developed a method of removing these plasmids from the cell and then reinserting them in other cells. Combining this process with that of DNA splicing enabled Boyer and Cohen to recombine segments of DNA in desired configurations and insert the DNA in bacterial cells, which could then act as manufacturing plants for specific proteins. This breakthrough was the basis upon which the discipline of biotechnology was founded.

  1. Herbert Boyer: A scientist born in 1936, known for his contributions to biotechnology, including the discovery of restriction enzymes and the development of recombinant DNA technology.
  2. Stanley Cohen: A Stanford scientist who collaborated with Herbert Boyer in the development of recombinant DNA technology. He was instrumental in the study of plasmids and their role in genetic engineering.
Biotechnology Principle and Process Class 12 Explanation

Biotechnology involves utilizing live organisms or enzymes from organisms to create products and processes beneficial to humans. This includes familiar processes like making curd, bread, or wine, which are microbe-mediated.

However, the term is now commonly associated with processes that use genetically modified organisms to achieve these tasks on a larger scale. Additionally, biotechnology encompasses various other techniques such as in vitro fertilization, gene synthesis and usage, DNA vaccine development, and gene correction.

The European Federation of Biotechnology (EFB) provides a comprehensive definition of biotechnology that combines traditional and modern molecular biotechnology. According to EFB, biotechnology is defined as “the integration of natural science and organisms, cells, parts thereof, and molecular analogs for products and services.”

Two fundamental techniques have been instrumental in shaping modern biotechnology:

  1. Genetic engineering: This involves methods to modify the chemistry of genetic material (DNA and RNA).

To introduce these changes into host organisms and alter the host organism’s phenotype, two main techniques are employed

(i) Genetic engineering involves altering the chemistry of genetic material (DNA and RNA) to introduce desired traits into the host organism.

(ii) Maintaining a sterile (microbial contamination-free) environment in chemical engineering processes ensures the growth of only the desired microbe or eukaryotic cell in large quantities. This is crucial for manufacturing biotechnological products like antibiotics, vaccines, and enzymes.

The conceptual development of genetic engineering principles begins with understanding the advantages of sexual reproduction over asexual reproduction.

Sexual reproduction allows for variations and unique combinations of genetic makeup, which can benefit the organism and the population. Traditional hybridization procedures in plant

and animal breeding often lead to the inclusion of undesirable genes alongside desired ones. Genetic engineering techniques, such as creating recombinant DNA, gene cloning, and gene

transfer, overcome this limitation by allowing the isolation and introduction of only the desired genes without introducing undesirable ones.

When a piece of DNA is transferred into an alien organism, it may not be able to multiply in the progeny cells initially. However, when integrated into the recipient’s genome, it can multiply and be inherited along with the host DNA.

This integration occurs because the alien DNA becomes part of a chromosome, which contains an origin of replication responsible for initiating replication.

This process allows the alien DNA to replicate and multiply itself in the host organism, known as cloning or making multiple identical copies of any template DNA.

The construction of the first recombinant DNA molecule involved linking a gene encoding antibiotic resistance with a native plasmid (autonomously replicating circular extra-chromosomal DNA) of Salmonella Typhimurium.

Stanley Cohen and Herbert Boyer achieved this in 1972 by isolating the antibiotic resistance gene from a plasmid responsible for conferring antibiotic resistance. This was made possible by the discovery of restriction enzymes, which cut DNA at specific locations, enabling the manipulation of DNA segments.

Restriction enzymes, also known as ‘molecular scissors’, cut DNA at specific locations. The cut DNA piece is then linked with plasmid DNA, which acts as a vector to transfer the attached DNA piece.

Similarly to how a mosquito acts as an insect vector to transfer the malarial parasite into the human body, a plasmid can be used as a vector to deliver an alien piece of DNA into the host organism.

The linking of the antibiotic resistance gene with the plasmid vector is made possible by the enzyme DNA ligase, which joins the ends of cut DNA molecules to create recombinant DNA.

When this recombinant DNA is transferred into Escherichia coli (E. coli), a bacterium closely related to Salmonella, it can replicate using the host’s DNA polymerase enzyme and make multiple copies. This ability to multiply copies of the antibiotic resistance gene in E. coli is called cloning of the antibiotic resistance gene in E. coli.

The process of genetically modifying an organism involves three basic steps:

(i) Identifying DNA with desirable genes.

(ii) Introducing the identified DNA into the host.

(iii) Maintaining the introduced DNA in the host and transferring the DNA to its progeny.

To accomplish genetic engineering or recombinant DNA technology, key tools are required, including restriction enzymes, polymerase enzymes, ligases, vectors, and the host organism.

Restriction enzymes were first isolated in 1963 and are responsible for restricting the growth of bacteriophage in Escherichia coli. One of the enzymes adds methyl groups to DNA, while the other cuts DNA, known as the restriction endonuclease.

Hind II was the first restriction endonuclease isolated, which always cuts DNA molecules at a specific point by recognizing a specific sequence of six base pairs called the recognition sequence for Hind II.

Today, more than 900 restriction enzymes have been isolated from over 230 strains of bacteria, each recognizing different recognition sequences. These enzymes are named based on the genus and species of the prokaryotic cell from which they were isolated.

For example, EcoRI comes from Escherichia coli RY 13, where the letter ‘R’ is derived from the name of the genus.

Restriction enzymes belong to the category of nucleases, which are enzymes that interact with DNA. Nucleases are of two types: exonucleases and endonucleases. Exonucleases remove nucleotides from the ends of DNA molecules, while endonucleases make cuts at specific positions within the DNA.

Each restriction endonuclease functions by examining the length of a DNA sequence. When it encounters its specific recognition sequence, the enzyme binds to the DNA and cuts each of the two strands of the double helix at specific points along their sugar-phosphate backbones.

This recognition sequence is typically a specific palindromic nucleotide sequence in the DNA, meaning that it reads the same forward and backward.

Restriction enzymes are crucial in genetic engineering for creating recombinant DNA molecules. These enzymes cut DNA strands slightly away from the center of the palindrome sites, leaving single-stranded portions with overhanging stretches called sticky ends.

These sticky ends can form hydrogen bonds with their complementary cut counterparts, facilitating the action of DNA ligase.

When DNA is cut by the same restriction enzyme, resulting fragments have matching sticky ends, enabling them to be joined together using DNA ligases. This process allows for the creation of recombinant DNA molecules containing DNA from different sources or genomes.

You may have realized that normally unless one cuts the vector and the source DNA with the same restriction enzyme, the recombinant vector molecule cannot be created.

Separation and isolation of DNA fragments: The cutting of DNA by restriction endonucleases results in the fragments of DNA. These fragments can be separated by a technique known as gel electrophoresis.

Since DNA fragments are negatively charged molecules, they can be separated by forcing them to move toward the anode under an electric field through a medium/matrix. Nowadays,

the most commonly used matrix is agarose, which is a natural polymer extracted from seaweeds. The DNA fragments separate (resolve) according to their size through the sieving effect provided by the agarose gel. Hence, the smaller the fragment size, the farther it moves. Look at Figure 11.3 and guess at which end of the gel the sample was loaded.

The separated DNA fragments can be visualized only after staining the DNA with a compound known as ethidium bromide followed by exposure to UV radiation (you cannot see pure DNA fragments in visible light and without staining).

You can see bright orange-colored bands of DNA in an ethidium bromide-stained gel exposed to UV light (Figure 11.3). The separated bands of DNA are cut out from the agarose gel and extracted from the gel piece. This step is known as elution.

The DNA fragments purified in this way are used in constructing recombinant DNA by joining them with cloning vectors.

11.2.2 Cloning Vectors

You know that plasmids and bacteriophages have the ability to replicate within bacterial cells independent of the control of chromosomal DNA.

Bacteriophages, because of their high number per cell, have very high copy numbers of their genome within the bacterial cells. Some plasmids may have only one or two copies per cell, whereas others may have 15-100 copies per cell.

Their numbers can go even higher. If we are able to link an alien piece of DNA with bacteriophage or plasmid DNA, we can multiply its numbers equal to the copy number of the plasmid or bacteriophage. Vectors used at present are engineered in such a way that they help easy linking of foreign DNA and selection of recombinants from non-recombinants.

The following are the features that are required to facilitate cloning into a vector:

(i) Origin of replication (ori): 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 supports a high copy number.

(ii) Selectable marker: In addition to ‘ori’, the vector requires a selectable marker, which helps in identifying and eliminating non-transformants and selectively permitting the growth of the transformants.

Transformation is a procedure through which a piece of DNA is introduced into a host bacterium. Normally, the genes encoding resistance to antibiotics such as ampicillin,

chloramphenicol, tetracycline, or kanamycin, etc., are considered useful selectable markers for E. coli. The normal E. coli cells do not carry resistance against any of these antibiotics.

(iii) Cloning sites: In order to link the alien DNA, the vector needs to have very few, preferably single, recognition sites for the commonly used restriction enzymes. The presence of more than one recognition site within the vector will generate several fragments, which will

complicate gene cloning. The ligation of alien DNA is carried out at a restriction site present in one of the two antibiotic-resistance genes. For example, you can ligate foreign DNA at the BamH I site of the tetracycline resistance gene in the vector pBR322. The recombinant plasmids will lose tetracycline resistance due to the insertion of foreign DNA but can still be

selected from non-recombinant ones by plating the transformants on an ampicillin-containing medium. The transformants growing on an ampicillin-containing medium are then transferred to a medium containing tetracycline.

The recombinants will grow in an ampicillin-containing medium but not on that containing tetracycline. However, non-recombinants will grow on the medium containing both antibiotics. In this case, one antibiotic resistance gene helps in selecting the transformants, whereas the other antibiotic resistance.

Biotechnology Principle and Process class 12 summary

Biotechnology involves the large-scale production and marketing of products and processes using live organisms, cells, or enzymes. Modern biotechnology, using genetically modified organisms, became possible when humans learned to alter the chemistry of DNA and

construct recombinant DNA. This process, known as recombinant DNA technology or genetic engineering, utilizes restriction endonucleases, DNA ligase, appropriate plasmid, or viral vectors to isolate and transport foreign DNA into host organisms. Subsequently, the foreign gene is expressed, and the gene product, typically a functional protein, is purified. Finally, a suitable formulation is prepared for marketing. Large-scale production often involves the use of bioreactors.

Biotechnology Principle and Process class 12 Question and Answer

Question:1 From what you have learned, can you tell whether enzymes are bigger or DNA is bigger in molecular size? How did you know?

Answer : Compared to DNA molecules, enzymes are smaller in size. We can say this as DNA comprises genetic material essential for the normal development and functioning of living entities. A DNA molecule consists of instructions required for the synthesis of DNA molecules and proteins. Whereas enzymes are the proteins that are synthesized from genes – a small fragment of DNA. These are crucial in the production of the polypeptide chain.

Question:2 Do eukaryotic cells have restriction endonucleases? Justify your answer.”use easy words”

Answer: No, eukaryotic cells do not have restriction endonucleases. These enzymes are typically found in prokaryotic cells like bacteria. Eukaryotic cells, which include plants, animals, fungi, and protists, have different mechanisms to protect their DNA and regulate genetic processes. While eukaryotic cells have enzymes that can modify DNA, they don’t possess restriction endonucleases, which are specific to prokaryotic cells.

Question:3 Can you recall meiosis and indicate at what stage a recombinant DNA is made?

Answer: Meiosis is a type of cell division that occurs in sexually reproducing organisms, resulting in the formation of gametes (sperm and egg cells) with half the number of chromosomes as the parent cell. Recombinant DNA is not directly formed during meiosis.

Recombinant DNA technology, on the other hand, involves the artificial joining of DNA from different sources. This process typically occurs in the laboratory setting and is not a natural part of meiosis. Recombinant DNA is created during genetic engineering processes, where specific DNA sequences from different organisms are combined using enzymes like restriction endonucleases and DNA ligases.

So, to answer your question, recombinant DNA is made during genetic engineering procedures in the laboratory and is not a part of the natural stages of meiosis.

Question:4 What are competent cells? What does the word “competent” refer to?

Answer: Competent cells are like supercells that scientists make in the lab. They’re called “competent” because they’re really good at taking in DNA from outside. It’s a bit like opening a door for DNA to come inside the cell.

Scientists treat these cells with special chemicals or changes in temperature to make them more open to taking in DNA. Once the DNA is inside these competent cells, it can become a part of the cell’s own DNA. This process is important for many experiments in biology where scientists need to introduce new DNA into cells for research or other purposes.

Biotechnology Principle and Process class 12 MCQ

Question:1 What is the primary goal of biotechnology?

  1. A) To manipulate living organisms for human benefit
  2. B) To study the behavior of animals
  3. C) To understand the ecosystem
  4. D) To explore space

Question:2 Which of the following is not a technique used in modern biotechnology?

  1. A) Genetic engineering
  2. B) Microscopy
  3. C) Polymerase chain reaction (PCR)
  4. D) Gel electrophoresis

Question:3 What is the purpose of gel electrophoresis in biotechnology?

  1. A) To visualize DNA fragments
  2. B) To observe cell structures
  3. C) To analyze protein sequences
  4. D) To study enzyme reactions

Question:4 Which enzyme is responsible for cutting DNA at specific sequences?

  1. A) DNA ligase
  2. B) Restriction endonuclease
  3. C) Polymerase chain reaction
  4. D) Helicase

Question:5 What is the function of DNA ligase in genetic engineering?

  1. A) It cuts DNA at specific sequences
  2. B) It amplifies DNA fragments
  3. C) It joins DNA fragments together
  4. D) It visualizes DNA under UV light

Question:6 Which of the following is not a requirement for cloning vectors?

  1. A) Origin of replication
  2. B) Selectable marker
  3. C) Cloning sites
  4. D) Ribosomes

Question:7 What is the purpose of selectable markers in cloning vectors?

  1. A) To identify non-transformants
  2. B) To visualize DNA fragments
  3. C) To cut DNA at specific sequences
  4. D) To facilitate DNA replication

Question:8 Which enzyme is used to amplify DNA fragments in PCR?

  1. A) DNA ligase
  2. B) Restriction endonuclease
  3. C) DNA polymerase
  4. D) RNAase

Question:9 What is the role of bioreactors in biotechnology?

  1. A) To visualize DNA fragments
  2. B) To amplify RNA molecules
  3. C) To facilitate large-scale production
  4. D) To study enzyme kinetics

Question:10 What is the main focus of modern biotechnology

  1. A) Studying ancient civilizations
  2. B) Manipulating genetic material
  3. C) Exploring deep-sea creatures
  4. D) Analyzing space phenomena

MCQ Answers

Question NoAnswer Question NoAnswer

Read also

  1. Reproduction in Organisms class 12 chapter 1
  2. Human Reproduction Class 12
  3. Human Reproduction Class 12 Chapter 3

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