Biotechnology in Medicine | Biology Class 12 - NEET PDF Download

Introduction

The recombinant DNA technological processes have made immense impact in the area of healthcare by enabling mass production of safe and more effective therapeutic drugs. Further, the recombinant therapeutics do not induce unwanted immunological responses as is common in case of similar products isolated from non-human sources. At present, about 30 recombinant therapeutics have been approved for human-use the world over. In India, 12 of these are presently being marketed.

1. Genetically Engineered Insulin 

Maturation of Pro-insulin into Insulin 

Managing adult-onset diabetes by taking insulin regularly is essential. However, if there is a shortage of human insulin:

• Alternative Sources: Patients may need to consider using insulin from other animals.
• Effectiveness: Insulin from animals may work but might not be as effective as human insulin, and it could trigger immune responses.
• Bacteria-Based Solution: Alternatively, if bacteria capable of producing human insulin are available, the process becomes more straightforward.
• Oral Administration: Insulin cannot be administered orally because it gets digested in the stomach before reaching the bloodstream.

Historically, diabetes patients used insulin extracted from cattle and pigs, which sometimes caused allergic reactions due to differences in the protein.

Insulin consists of two polypeptide chains (A and B) connected by disulfide bonds (S-S ). In mammals, including humans, insulin starts as a pro-hormone with an extra C peptide, which is removed during maturation into insulin.

Sir Edward Sharpy-Shafer (1916) was the first to not that diabetes of some persons was because of failure of some islands of pancreas to produce a substance which he called insulin (derived from the latin, insula, meaning island).
Banting and Best (1921) were the first to isolate insulin from dog's pancreas and used it to cure diabetes in man.

The source of insulin used for curing diabetes these days, is the pancreas of slaughtered cattle and pigs.
Through this insulin is effective in controlling diabetes, it results in certain undesirable effects.
The first genetically engineered insulin obtained by recombinant DNA technique with the help of E. Coli was produced by the American firms, Eli-Lilly on July 5, 1983. It has been given the trade name humulin and has been approved for clinical use.

2. Gene Therapy

Gene Therapy

• Gene therapy aims to correct hereditary diseases by fixing faulty genes in individuals, even before birth.
• This involves inserting healthy genes into a person's cells to treat the disease.
• The first gene therapy was given in 1990 to a 4-year old girl with ADA deficiency, which affects the immune system.
• ADA deficiency can be managed with treatments like bone marrow transplants or enzyme replacement therapy, but these are not always fully curative.
• In gene therapy, patient's blood cells are grown outside the body, and a working ADA gene is introduced into these cells using a retroviral vector.
• These modified cells are then put back into the patient, but they are not everlasting, so the patient needs periodic infusions.
• If the healthy ADA gene is introduced into cells at an early embryonic stage, it could offer a permanent cure.

3. Molecular Diagnosis

Importance of Early Disease Detection:

• Early diagnosis is crucial for effective disease treatment.
• Conventional methods like blood and urine tests often can't detect diseases in their early stages.

Molecular Diagnosis Techniques:

Recombinant DNA technology, Polymerase Chain Reaction (PCR), and Enzyme-Linked Immuno-Sorbent Assay (ELISA) are powerful tools for early diagnosis.

• PCR for Detecting Low DNA Levels:  PCR can find tiny amounts of DNA, even before disease symptoms appear. It's used to detect HIV in AIDS patients and gene mutations in cancer patients. PCR is valuable for identifying various genetic disorders.
• DNA Hybridization and Mutations: To identify mutated genes, single-stranded DNA or RNA is tagged with a radioactive molecule (probe). This probe binds to complementary DNA in cell clones, and mutated genes won't match, so they won't appear in the results.
• ELISA and Antigen-Antibody Interaction: ELISA works on the principle of detecting antigens (like proteins) or antibodies produced in response to pathogens. It's a method to identify infections by looking for these markers in a person's body.

Old NCERT Syllabus

VITAMINS:

Definition :-"Vitamins are complex organic substances found in various food and required for specific metabolic reaction in cells. "The term vitamin first of all used by Funk and first of all Vit-B1 also isolated by him, Vit-C isolated by A.S.Gyorgy. The first vitamin to be produced by fermentation was Vit-C by A.S. Gyorgy also Vit-A was isolated by Mc Collum and Vit-D by Millanby.

Microbes are important commercial sources of several vitamins. Some examples are given here :-

1. Riboflavin (vitamin B₂) :- This found in cereals, vegetables and Brewer's yeast was first produced in 1938. It is a crystalline, bitter, odourless, yellowish brown chemical and is essential for growth and reproduction in animals. The main sources of Riboflavin are fungi– Ashbya gossypii and the yeast like Eremothecium ashybyii. By the use of original wild strain of mould Ashbya gossypi, production of Vit-B2 increase 100-300 times more.

2. Cobalamin or Vitamin B₁₂ :- First isolated from liver extract in 1948. It is a compound which contains cobalt, and is now obtained in a cobalt rich substrate (eg. corn sugarcane molasses or starch) by microbes such as Propionibacterium frendenreichii, Bacillus megatherium.

Vitamin B₁₂ is used to supplement animal feed, and in man for increasing appetite and for treating Anaemia. By the use of Mutant strains of Pseudomonas denitrificans, production of Vit-B12 increased 50,000 times more.

3. Ascorbic Acid (Vitamin C) :- It is manufactured from L.Sorbose which is commercially produced from Sorbitol by Biological dehydrogenation brought about by different species of Acetobacter.

ANTIBIOTICS

The term was coined by Selman Waksman (1942).

Definition:-"An antibiotic is a substance produced by a microorganism which in low concentration inhibits the growth and metabolic activity of pathogenic organism without harming the host."

Alexander Flemming was first to produce and antibiotic named penicillin from Penicillium notatum.

Waksman and Albert discovered Streptomycin and Actinomycin.

Burkholder isolated Chloromycetin.

Antibiotics are of two types :-

1. Broad spectrum Antibiotic :- It is an antibiotic which can kill or destroy a number of pathogens that belong to different groups with different structure and wall composition.

2. Limited spectrum (Specific) antibiotic :- It is an antibiotic which is effective only against one type of pathogens.

Action of Antibiotics :- An antibiotic acts on pathogen by:

(1) disruption of wall synthesis.

(2) Disruption of plasmalemma repair and synthesis.

(3) inhibition of DNA/RNA/Protein synthesis.

Good Antibiotic :-

A. Harmless to host with no side effect.

B. Harmless to normal micro-flora of Alimentary canal.

C. Ability to destroy pathogen as well as broad spectrum.

D. Effective against all strains of pathogen E. Quick Action Resistance to Antibiotics :-Pathogens often develop resistance to existing antibiotics so that newer antibiotics are required to be produced.

The resistance is produced due to :-.

i Development of copious mucilage.

ii. Alteration of cell membrane so that antibiotic cannot recognise the pathogen.

iii. Change to L-form by pathogen. 

iv. Mutation in pathogen.

Main sources of Antibiotic :-The main sources of Antibiotics production are three types – 

(i) Eubacterials – Most of this type of antibiotic is obtained from Bacillus spp 70%. Bacillus subtilis produced more than 60 Antibiotics and from Pseudomonas species 30%.

(ii) Actinomycetales [Ramified ] – Streptomyces, Micromonospora and streptosporangium. From single species Streptomyces griseus more than 40 antibiotics have been obtained.

(iii) Fungi – Penicillium.

4. STEROIDS

They are complex crystallisable lipids having a tetracyclic hydrocarbon core (one 5-carbon and three 6 carbon rings) and a long side chain. They are constituents of hormones and some important biochemicals like cholesterol, progesterone, oestrogen, testosterone, corticosterone, and cortisone. Compounds of steroids are found in both animals and plants. The main important steroid which is found in animals i.e. Cholestrol. It is the main constituent of animal cell membrane and main point for the initiation of steroid in hormone inside the body.

Steroids are used medicinally in correcting hormonal imbalance, Anabolic stimulants, Birth control pills, anti-fertility drugs, Anti-inflammatories, relieving pain and suppressing immune responses various steroids differ from one another in radicals like –OH = O, –CO–CH₃, –COCH₂OH.

Murray and Peterson (1950) found that Rhizopus stolonifer could bring about hydroxylation required for steroid synthesis including removal of hydrogen [dehydrogenation] from specific carbons.

Different microorganisms produce different steroids from progesterone like pregnane, cortexolone, Androsterone etc. The commercial conversion of Cortixolone to Predinisolone which is used as Antiflammatory drugs, involves first hydroxylation then dehydrogenation.

ORGANIC ACIDS:

Some organic acids are manufactured by employing fermentation activities of Fungi and others of Bacteria.

For example :-

1. Citric Acid :- It is obtained by the aerobic fermentation of sucrose by the fungus Aspergillus niger. This acid is used in medicine, flavoring extracts, food and candies; the manufacture of ink, dyeing. It is also produced by yeast.

2. Acetic acid or Vinegar :- Vinegar production is a two step fermentation process :-

A. First step:- Alcoholic fermentation of a carbohydrate into alcohol by yeast.

B. Second step : Aerobic oxidation of alcohol into acetic acid by the Bacterium Acetobactoer aceti.

Vinegar is a French word, meaning - sour wine, and was known to man thousands of years ago.

The Vinegar is the product of microbial fermentation, was recognized by Kutzing in 1837. In 1868 Pasteur discovered it to be a result of Biological Activity.

Vinegar is used in various ways in homes. It is used as a condiment and for preserving pickles, canned vegetables and fruits.

Medicinally, it has an important role in promoting digestion and in overcoming constipation.

3. Lactic Acid :– Produced by fermentation of corn starch, Molasses potatoes and whey by Lactobacillus bulgaris and Streptococcus lactis.

4. Gluconic acid:– Produced from glucose by fungus like Aspergillus, Penicillium and Mucor.

5. Fumaric acid – Produced from Sugar by activity of Rhizopus nigricans [Bread mould]

6. Butyricacid – Obtained by clostidium butylicum.

INTERFERON
First of all Issac and Lindemann observed that immunity due to the formation of special soluble substances, produced by viral infected cells. This small group of protein is named - Interferons.
These are the proteins released by the cells in response to a viral infection which they help to combat. These interferon do not inactivate the virus, but they make the unattacked cells, less susceptible so they are prevented from the attack of virus. They also prevent the viruses from taking over the cellular machinery. Interferon proteins have proved to be effective in treating influenza and hepatitis, but their role in cancer treatment is doubtful. Interferon produced by Charlse Weisman through the E.coli strain produced by Recombinant DNA technology.

There are three major types of interferons :
(1) Interferon-a (INF - a, produced by leucocytes or white blood cells,)
(2) Interferon-b (INF - b, produced by fibroblasts), and
(3) Interferon-g  (INF -g  produced by stimulated T-lymphocyte cells, hence also called immune interferon.

DEXTRINS
It is a plasma expander having 6-10% solution of dextrins which is given in case of haemorrhage, shock and dehydration and plasma transfusion.

Dextrins are soluble polyglycan for polymers of D-glucose. They are prepared either through partial hydrolysis of starch or partial polymerisation of simple sugars through microorganism Leuconostoc mesenteroides or Enzyme dextran sucrase. The enzyme is more useful as dextran or dextrin of suitable molecular weight can be obtained more easily.

VACCINES
Production of antibodies against of antigens inside the body is the basis of immunity. Process of innoculation of vaccines is called vaccination. Scientific base of vaccination was established by Louis Pasteur. First vaccine discovered by Edward Jenner for small pox.
A vaccine contains either weakened or even killed-attenuation pathogens [serum suspension with virulence] which have still antigens to induce antibody production. All these vaccines are called First generation vaccines.
They are produced by conventional technique.
Recently new vaccines are produced called second generation vaccines. These are produced by Recombinant DNA technology [Genetic Engineering] e.g., Herpes Virus and Hepatitis-B.
Latest vaccines produced synthetically or synthesized vaccines are called third generation vaccines.

AN IDEAL VACCINE
1. It should not be tumerogenic or toxic or pathogenic, i.e., it should be safe.
2. It should have very low levels of side effects in normal individuals.
3. It should not cause problems in individuals with impaired immune system.
4. It should not spread either within the vaccinated individual or to other individuals (live vaccines.)
5. It should not contaminate the environment.
6. It should be effective in producing long lasting humoral and cellular immunities.
7. The technique of vaccination should be simple.
8. The vaccine should be cheap so that it is generally affordable. So far, such an ideal vaccine has not been developed.

PLANT TISSUE CULTURE

Now a days plant tissue culture technique utilized for the production of important compounds, such as Red dye–is called Shikonin which is obtained from Lithospermum erythrorhizon.
It is utilized for the formation of cosmetic materials.

Note :(i) Antirabies vaccine obtained from culture of chick embryo cells [Rabipur] (ii) Probiotics : These are dietary nutritional supplements containing micro-organisms (eg. Sporlac tablet containing lactobacillus) Some special Techniques Utilized in Biotechnology – Recombinant

DNA technology – A recombinant DNA molecule is produced by joining together two or more DNA segments usually originating from different organisms. More specifically, a recombinant DNA ,molecule is a vector (e.g., a plasmid, phage or virus) into which the desired DNA fragment has been inserted to enable its cloning in an appropriate host.

Recombinant DNA molecules are produced with one of the following three objectives :
(1) To obtain a large number of copies of specific DNA fragments,
(2) To recover large quantities of the protein produced by the concerned gene.
(3) To  integrate the gene in question into the chromosome of a target organism where it expresses it self.

This technique developed by Genetic engineering. In this techniques first of all isolation of desired gene from any organisms and its transfer and expression into any organism of choice. They are known as transgenic
micro-organisms. Transgenic micro organisms are produced with view to obtain novel pharmaceutical proteins.

For example – Human Insulin is being produced commercially from Transgenic E.coli strain.
Many valuable recombinant proteins are also being produced, using transgenic animal cells lines and transgenic plants.
At the same time, a number of these proteins of great medicinal value could not be produced on a commercial scale using the non-transgenic cells or organisms.

Proteins produced by transgens are called "recombinant proteins". Such type of recombinant genes are utilized for the formation of different products.
Plants, bacteria, fungi and animals whose genes have been altered by manipulation are called Genetically Modified Organisms (GMO).
Genetically modified crops – A transgenic crop is a crop that contains and expresses a transgene. This crop is known as genetically modified crops or GM crops.

Two unique advantages :-

(i) Any gene (from any organism or a gene synthesised chemically) can be used for transfer, and
(ii) The change in genotype can be precisely controlled since only the transgene is added into the crop genome.For example –Hirudinis a protein that prevents blood clotting. The gene incoding hirudin was chemically synthesized and transferred into Brassica napus. Where hirudin accumulates in seeds. The hirudin is purified and used in medicine.

A soil bacteriumBacillus thuringiensis, producescrystal [Cry]protein. This Cry protein is toxic to Larvae of certain insects. Each Cry protein is toxic to a different group of insects. The gene encoding cry protein is called "cry gene". This Cry protein isolated and transferred into several crops. A crop expressing a cry gene is usually resistant to the group of insects for which the concerned Cry protein is toxic. There are a number of them, for example, the proteins encoded by the genes cryIAc and cryllAb control the cotton bollworms, that of cryIAb controls corn borer.

However, gene symbol italics, e.g., cry. The first letter or the protein symbol, on the other hand, is always capital and the symbol is always written in roman letters, e.g., Cry.

Bt Cotton : Some strains of Bacillus thuringiensis produce proteins that kill certain insects such as lepidopterans (tobacco budworm, armyworm), coleopterans (beetles) and dipterans (flies, mosquitoes). B. thuringiensis forms protein crystals during a particular phase of their growth. These crystals contain a toxic insecticidal protein . The Bt toxin protein exist  as inactive protoxins but once an insect ingest the inactive toxin, it is converted into an active form of toxin due to the alkaline pH of the gut which solubilises the crystals. The activated toxin binds to the surface of midgut epithelial cells and create pores that cause cell swelling and lysis and eventually cause death of the insect.

Transgenic variety of Tomato – Flavr Savr due to the inhibition of polygalacturonase enzyme which degrades pectin. So that tomato variety remains fresh and retain flavour much longer.

GM crops are already in cultivation in U.S.A., Europe and several other countries. In India, some insect resistant cotton varieties expressing cry genes have reached the farmers, fields. It has been argued that transgenic crops may be harmful to the environment. The three points. Firstly, the transgene may be transferred through pollen from these crops to their wild relatives.

Secondary, the transgenic crops may themselves become persistent weeds. Thirdly, GM crops may pollute the environment.