8. CELL BIOLOGY & BIOTECHNOLOGY

                                       8. CELL BIOLOGY AND BIOTECHNOLOGY

Cell: The structural and functional unit of the body is called as cell.

Tissue: A group of cells that performs the similar function is called as tissue.

Cytology: The branch of biology which deals with the study structure, types and organelles of the cell, cell division and other aspects of the cell is called as cytology.

                  National Centre for Cell Science – Pune

                  Instem– Bengaluru

Stem Cells

Special types of cells present in the body of a multicellular organisms that can give rise to cells of all other types are called as stem cells.

The zygote formed after fertilization of gametes contains mass of cells, which are similar cells. These are the stem cells. They can give rise to new organism. Stem cells can be used to produce new tissues in laboratory. These cells also play important role in wound healing.

Differentiation of stem cells

 Stem cells can form any type of cell during the further development. The formation of different types of tissues to perform specific and different functions is called as differentiation of the stem cells. Once the new tissues are formed their capacity to differentiate is lost. Later they can form cells which are similar to them.

Sources of stem cells

Stem cells are present in the umbilical cord of pregnant mother, in embryo, in red bone marrow, in blastocyst stage of embryonic development, in blood, in adipose connective tissue of adult human beings and also in placenta.

Preservation of stem cells

The stem cell samples are carefully collected from umbilical cord blood, red bone marrow or early embryo and are preserved in small, sterile vials. These vials are stored in liquid nitrogen at -135⁰C to -190⁰C.

Types of stem cells

Depending upon source, stem cells are of two types as follows

1) Embryonic stem cells:

Embryo is formed by divisions of zygote. These embryonic cells continuously divide by mitosis. These cells are stem cells. But by the 14^th day of conception cell differentiation starts. This differentiation causes formation of 220 different types of cells i.e. osteocytes, hepatocytes and neurons from the cells. Before the cell differentiation, the embryonic cells are called as embryonic stem cells. These stem cells are primary, undifferentiated cells having ability to multiply. These cells are the parent cells of all types of human cells.

The property of stem cells to develop into different types of cells is called as pleuripotency.Stem cells can collected well before the beginning of differentiation i.e. during 5^th- 7^th day and cultured with certain biochemical stimuli in laboratory. Based on the type of stimulus, stem cells transforms themselves into desired type of cells, later tissues and then organs.

2) Adult stem cells:

                              Stem cells obtained from the adult body are called as adult stem cells. Stem cells can be obtained from the red bone marrow, adipose connective tissue and blood. Stem cells can be obtained from the cord blood immediate after birth.

Uses of stem cells

1) Stem cells are used to replace the dead and functionless cells in case of conditions like    diabetes, myocardial infarction, Alzheimer’s disease, Parkinson’s disease etc.

2) Stem cells are used to produce blood cells required conditions like anemia, thalassemia,           leukemia etc.

3) In organ transplantation, stem cells can used and they can help in the transplantation of of new organs.

Organ transplantation 
If less efficient or completely functionless organ of the body is changed, the life of such patient can be saved. Kidney or skin transplantation can be done on the patient if there is suitable Donor for the same. Availability of healthy donor is an important requirement in organ transplantation. Various factors like blood group, diseases, disorders, age, etc of the donor and recipient need to be paid attention during transplantation.For kidney and skin live Donor can be taken but Liver,heart, eyes can be donated after death.

                          Organ and body donation
The body is not of any use after the death. Many organs remain functional for certain period even after death occurs under specific conditions. Such organs can be used to save the life of other needful persons.
            Life of many people can be saved by organ and body donation. Blinds can regain the vision. Liver, kidney, heart, heart valves, skin, etc. can be donated. Similarly body can be made available for research in medical studies.

Question: Why some of the organs in human body are most valuable?
Ans- 1) The body can be in best health if all the vital organs of the body are also in the best condition.
2) Brain, kidney, heart, liver etc. are some such vital organs which are the most essential for proper metabolism and functioning of the body
3) One cannot survive if any of the vital organs are not functioning properly.

                                  Biotechnology
Biotechnology is bringing about artificial genetic changes and hybridization in organisms for human welfare.
     Cytology, biochemistry, molecular biology and genetic engineering are different branches of science that are included in biotechnology. Improving the agricultural field production of high class varieties of crops and suitable form products through tissue culture are the aspects in which biotechnology is largely used. Pharmaceutical experiments to produce antibodies vitamins and hormones like insulin are taking support of biotechnological principles.

                                         Main areas in biotechnology

1)    Microbiology-Using microbial abilities to form Yoghurt from milk & alcohol from molasses.
2) By increasing the productivity of the specific cell to manufacture antibiotics and vaccines.
3) Use of biomolecules like DNA and protein in human welfare.
4) Development of plants animals and products of desired quality by gene manipulation.
5) Production of human growth hormone with the help of genetically modified bacteria.
6) By using entire cell or tissue non genetic biotechnology experiments are done.

 

 

Benefits of biotechnology

1) Increasing the per hectare yield of the crop land.
2) Development of disease resistant varieties of crops
3) Fast fruit setting varieties are developed that increase the per annum yield.
4) Development of stress resistant varieties which can with stand in adverse condition.

            Commercial applications of biotechnology
1) Crop biotechnology
a) Genes of two different crops are recombined to form hybrids of various crops. This is especially useful for fruits.
b) Crops developed with desired characters by integrating cl foreign gene with their genome are called a genetically modified crops.

BT cotton
A gene isolated from the bacterium bacillus thuringiensis and integrated it with the gene of cotton. The toxin which is fatal for bollworm was produced in leaves and bolls of cotton. If bollworm feeds on leaves the toxin destroys its elementary canal and the bollworm dies.

BT brinjal
This variety of brinjal is developed by using the gene isolated from bacillus thuringiensis. Is improved variety of brinjal is the pest as the BT Cotton does.

Golden rice
A gene synthesizing the vitamin A has been introduced in this variety of rice. As compared to the normal variety, this variety contains 23 times more amount of Beta carotene.

Herbicide tolerant plants

Due to biotechnology, herbicide tolerant plant varieties of crops are being developed. Due to this, it has become possible to selectively destroy the weeds.

C) Biofertilizers
Due to the use of biofertilizers instead of chemical fertilizers, nitrogen fixation and phosphate solubilization abilities of the plants are improved. Mainly the bacteria like rhizobium, azotobacter, nostoc, anabana and plants like azolla are used as biofertilizers.

 

 

2. Animal husbandry
Artificial insemination and embryo transfer are used in animal husbandry. It helps to improve both the quality and quantity of animal products. Animals with more strength have been developed for hard work.

3. Human health
To improve and to manage the human health diagnosis and treatment of diseases have to be focused. Diagnosis of diabetes, heart diseases and infectious diseases such as AIDS and dengue can be done rapidly due to biotechnology.

a) Vaccines and vaccination
Vaccine:
               The antigen containing material given to a person or animal to acquire either permanent or temporary immunity against a specific pathogen or disease is called a vaccine.

                        Vaccination
1) Vaccination is the administration of vaccine. Vaccine is the antigen. It is given to a person or even to animals for acquiring immunity against particular pathogens or diseases.
2) In olden days vaccines were prepared with the help of completely are partially killed pathogens.But this method causes some inconvenience. Some persons were allergic to such raw vaccines or they used to construct the same disease through vaccine.                                        3) Now the vaccines are produced by using biotechnology. These vaccines are artificial which are synthesized in the laboratory.
4) The antigen is produced with the help of gene of the pathogen such vaccine becomes safe for administering.
5) These antigenic proteins are injected to people to make their immune system strong. This process of vaccination is absolutely safe.

Edible vaccine
The vaccines which are given as a food by incorporating them into the food stuff are called as edible vaccines.
         Transgenic potatoes are produced with the help of biotechnology which contain vaccine that act against bacteria like vibrio cholerae and E. coli. If raw potatoes are consumed then the immunity is generated in the body of a person. However, eating only raw potatoes generate the immunity against cholera and the disease caused due to E. coli.

b) Treatment
                     Biotechnology is useful for production of hormones like insulin somatotropin and blood clotting factors.

c) Interferon
Interferon is a group of small sized protein molecule used in treatment of viral diseases. These are produced in blood. Nowadays with the help of biotechnology transgenic E. Coli are used for production of interferon.

 

d) Gene therapy
To treat genetic disorders in somatic cells has become possible by gene therapy due to biotechnology.
Example: phenylketonuria can be treated with gene therapy.

e) Cloning
Production of replica of any sale or organ or entire organism is called cloning.
There are two types of cloning namely reproductive cloning and therapeutic cloning.

1) Reproductive cloning
In reproductive cloning, a clone is produced by fusion of A nucleus of diploid somatic cell with the enucleated ovum of anybody. In the process the sperm or male gamete is not needed.

2) Therapeutic cloning
This technique is used for treatment purpose. Stem cells are derived from the sale formed in laboratory by the union of somatic cell nucleus with the enucleated egg cell.
     Gene cloning can also be done to for millions of copies of same gene such genes are used for gene therapy and other purposes. Due to cloning technique that Inheritance of hereditary diseases can be controlled continuation of generations can be achieved and certain characteristic genes can be enhanced.

3) Industrial Products / white biotechnology
                   Various industrial chemicals can be produced through less expensive processes    for example can be produced from sugar molasses with the help of transgenic yeast.

4) Environment and Biotechnology
                   Now it is possible to solve environment related various problems with the help of biotechnology. Microbes are useful on large scale while production of composed by treatment on solid organic waste material. Bioremediation,biopesticides,biofertilizers, biosensors etc. are some new concepts in biotechnological methods.

Bioremediation
                     Absorption or destruction of toxic Chemicals and harmful pollutant with the help of plants and micro-organisms is called as bioremediation.
If plants are used for this purpose it is called as phytoremediation.

* Pseudomonas bacteria are useful for cleaning the hydrocarbon and oil pollutants from soil & water.
* The fern Pterisvitata can absorb the arsenic from the soil.
* Sunflower can absorb uranium and arsenic.
* Grasses like alfalfa clover and rye are used in phytoremediation
* Genetically modified variety of Indian mustard can absorb Selenium from soil.
* The bacterium Deinococcousradiodurans is used to absorb the radiations from radioactive debris.

5. Food biotechnology
                                           Food items like bread cheese wine beer Yoghurt vinegar are produced with the help of microorganisms. These food items are probably the oldest one produced with the help of biotechnology.

6. DNA fingerprinting
                                         DNA sequence of each person is unique as that of the fingerprints. due to this identity of any person can be established with the help of its available DNA. This is called as DNA fingerprinting.

Significance of DNA fingerprinting
1) It is mainly used in forensic Sciences to confirm the identity of the criminal.
2) Identity of parents in case of disputed parentage for any child can be understood by taking DNA fingerprints of both the parents and child.

Note: 1) Oil eating bacteria was discovered by Dr.Anand Mohan chakravarty.
           2) Centre for DNA fingerprinting and Diagnostics is located in Hyderabad.

 

 

Dolly
1) Dolly was the first mammalian cloned Sheep.
2) It was born in Scotland by the process of cloning.
3) The Finn dorset ship was chosen and her diploid nucleus from the under cell was      introduced into the ovum is haploid nucleus was removed. This enucleated ovum was         of Scottish sheep.
4) The age was been introduced into uterus of another Scottish sheep and it grew into         Dolly.
5) Dolly resembled exactly like Finn dorset sheep whose diploid nucleus was used. None         of the characters of Scottish sheep was seen in Dolly.

 Important stages in agricultural development

Green Revolution

1) In agriculture different methods used to harvest maximum yield from minimum land these methods are collectively called as green revolution.
2) Dr. M. S.Swaminathan is called father of Green revolution in India while Dr. Norman Borlaug has done the similar efforts in US.
3) Improved varieties of wheat and rice proper use of fertilizers and pesticides and water management has led to the increased production of food grains and their by large population had been saved from hunger.
4) green revolution has created abundance of the grains for Indian population.

Research institutes and laboratories in India

1) Indian Agricultural Research Institute New Delhi
2) National citrus Research Institute Nagpur
3) Indian Institute of Sciences and national pomegranate Research Institute Solapur.

White Revolution

1) Few years back at some places milk and Milk products where abundant but they did not reach all the consumers.
2) Dr.VergheseKurien started the Cooperative Movement in the direction to produce Operation Flood.
3) The use of biotechnology was also done to increase the milk production.
4) Different experiments were performed for quality control, near dairy products where thought of and preservation methods were improved.
5) This created White Revolution Amul from Anand has now reached International standards.

Blue revolution

1) Production of various useful aquatic organisms with the help of water is called as Blue revolution
2) In India the aquaculture of different freshwater and Marine organisms is being done with the help of fishery scientists.
3) Government of India has over to increase the production by increasing the people for pisciculture by launching the program ‘Nil Kranti mission 2016’.
4) Freshwater fishes like Rohu, Catla and other fishery products like shrimp and lobsters are being cultured on large scale.

Fertilizers

Organic manure and chemical fertilizers are used in agriculture. Due to the use of manual water holding capacity of the soil improves. Upper layer of the soil Asian share in agriculture is formed due to the humus formation. Various Essential elements like npk can be available to crops due to earthworms and fungii. In hydroponics, Liquid chemical fertilizers are used. Excessive use of chemical fertilizers causes decrease in fertility of soil.

Insecticides

Plants have natural immunity to fight against infections. Natural pest control measures such as insectivorous frocks and birds keep the pest population under control. But in an attempt to increase the yield man excessively use the pesticides and insecticides. These are toxic to all resident organisms. The insecticides like DDT,  Malathion,  Chloropyriphos also contaminated water and soil.

 

 

Apiculture

1) Apiculture is rearing of honey bees to obtain products such as honey and wax.
2) In such, practice artificial hives are placed. By such practice, the honey can be extracted without causing any harm to the honey bees are their hives.

Cultivation of medicinal plants

1) In Ayurveda different medicines are traditionally obtained from plants.
2) Now due to deforestation, the medicinal plants and Herbs are becoming rare. Hence theircultivation is to be done.
3) The entire world people have understood the importance of Holy Basil, adulsa etc.
4) In some of the allopathic medicines too, the plant extracts are used.

Fruit processing

1) Fruits are perishable food stuff. They are spoil soon if not consumed immediately.
2) It needs the processing in such a way that it can be used throughout the year.
3) Fruit processing includes various  methods ranging from storage in cold storage to drying,    salting, air tight packing, preparing murabba, evaporating etc.
4) The preserve products also fetch financial benefits.

 

3. Chemical Reactions

Periodic Classification of Elements

 Elements are the simple substances which can not be converted into simpler substances by any physical or chemicalmeans. 

                                              118 elements are known to human being. The elements are classified into metal, non-metals and metalloids. This classification of elements is based on their properties.

👉 Metalloids :-

                         The elements which have the properties of both metals as well as non-                                  metals  are  called as  metalloids.

                                       Examples of metalloids are boron, silicon, germanium, arsenic,                                     antimony, polonium etc.

👉 Dobereiners Triads :

       A group of three elements having the similar chemical properties are called as triads.   He made made triads of the elements which were known at that trime.

                         💢    Lithium (Li). Sodium (Na), Potassium (K)

                         💢   Chlorine (Cl), Bromine (Br), Iodine (I)

                         💢   Sulphur (S), Selenium (Se), Tellurium (Te)

                         💢   Calcium (Ca), Strontium (Sr), Barium (Ba)

👉 Dobereiners Law Of Triads :

                This law states that in a triad, when the elements are arranged in the increasing order of their atomic masses, the mean of the atomic masses of the first & the last element is approximately equal to the atomic mass of the middle element.

Element	Li	Na	K
Atomic     mass             Number	7	23	39

According to Dobereiners Law,

Sum of atomic mass of Li and K = 7 + 39 = 46

Mean of atomic masses of Li and K = 46/2 = 23

Thus it is proved that, the arithmetic mean of atomic masses of the first and the last element is approximately equal to the atomic mass of the middle element.

Demerits of Dobereiner's Law

  👉 Dobereiner could arrange only some triads from the known  elements.

 👉  Other triads did not obey Dobereiner's law.

Newlands' Law of Octaves

This law states that,when the elements are arranged in the increasing order of their atomic masses the properties of the eighth element are similar to the first.

               It is found that sodium is the eighth element from lithium and both of them have similar properties.

The following table will illustrate the example.

     

H	Li	Be	B	C	N	O
F	Na	Mg	Al	Si	P	S
Cl	K	Ca	Cr	Ti	Mn	Fe

 

 

Demerits of Newlands’ law of octaves

·         👉 Newlands’ could arrange elements only up to calcium out of 56 elements.

·         👉 After calcium the law was not obeyed.

·         👉 He could arrange only 56 elements known at that time.

·         👉 He did not include inert elements because they were not discovered.

·         👉 He placed elements of different properties in the same position.

Mendeleev’s periodic table

Dmitri Mendeleev (Russian Scientist) developed the periodic table of elements during 1869 to 1872 A.D. It was the most important step in the classification of elements. Mendeleev considered atomic mass number as the fundamental property of elements.

§             Mendeleev’s periodic law:

“Properties of elements are the periodic functions of their atomic masses.”

 

§            Mendeleev’s periodic Table:

“The tabular arrangement of elements on the basis of Mendeleev’s periodic law is called as Mendeleev’s periodic Table.”

Features of Mendeleev’s periodic Table

·         The horizontal rows in the periodic table are called as periods. There are 7 periods in Mendeleev’s periodic Table.

·         The vertical columns in the periodic table are called as groups.

·         The eight groups are numbered from I to VIII. Groups from I to VIII are further sub-divided into A & B groups.

      Merits of Mendeleev’s periodic table

·                    🔘 Mendeleev arranged the elements in the increasing order of their atomic masses.

·                 🔘  He was the first person who successfully classified all known elements at that time.

·                  🔘 He kept some blank places in his table for those elements that were yet to be discovered.

·                 🔘 He also predicted the elements like eka - boron, eka - silicon and eka - aluminum.

·                🔘 When noble gases were discovered, they were placed in a new group without disturbing the                     position of others.

·                 Atomic masses of some elements were revised to give them proper place in periodic table.

Predicted elements	Actual Element Discovered Later
Eka-boron	Scandium
Eka-Aluminum	Gallium
Eka-Silicon	Germanium

   

 

 

 

     Demerits of Mendeleev’s periodic table

·              💬 Mendeleev could not assign a fixed position for hydrogen because the properties of hydrogen                   resembles with both alkali metals and halogens.

·              💬 Isotopes of the same elements have different atomic masses. They cannot be placed separately in             the periodic table.

·               💬 Some elements with higher atomic masses were placed before those having lower atomic masses.

      Example: Cobalt (58.95) was placed before Nickel (58.72)

·                💬 Some elements were placed in the same sub group had different properties.

     Example: Manganese is placed with halogens.

Modern periodic law

In 1938, the English scientist Henry moseley revealed that atomic number is a more fundamental property of an element than its atomic mass. Depending upon this fact he stated the modern periodic law as follows

"Properties of elements are a periodic function of their atomic numbers"

Modern periodic table

In the modern periodic table, the elements are arranged in the order of their increasing atomic numbers. The modern periodic table is also called the long form of the periodic table.

"The tabular arrangement of elements on the basis of modern periodic law is called as modern periodic table."

The relation between the atomic number of an element and its electronic configuration is clearly seen in the modern periodic table.

Structure of the modern periodic table

* in the modern periodic table from the elements are arranged in the order of their increasing atomic numbers.

* The horizontal rows in the modern periodic table are called as periods. There are 7 periods in the MPT.

* The vertical columns in the modern periodic table are called as groups. There are 18 groups in the MPT.

* The arrangement of the periods and groups results into formation of boxes.

* Each box represents the place for one element.

* At the bottom of the periodic table there are two rows which are called as lanthanide series and actinide series respectively.

* The periodic table is divided into four blocks namely s -block, p- block, d -block and f- block.

* A zig-zag line in the modern periodic table separates metals from the non-metals.

*Zig Zag line in the MPT represents metalloids.

*All the metals lie on the left side of the zig-zag line while all the non-metals lie on the right side.

Modern periodic table and electronic configuration of elements

The elements belonging to the same period differ slightly in their properties while the elements belonging to the same group show similarity and graduation in their properties. these characteristics of the periods and groups in the MPT are due to the electronic configuration of the elements. The position of the element in the group and in the period is decided by its electronic configuration.

1. Groups and electronic configuration

* The vertical columns in the periodic table are called as groups.

* There are 18 groups in the MPT and their numbered from 1 to 18.

* Group number indicates the number of valence electrons present in the outermost shell of the atom of an element.

                                       Group number = Number of valence electrons

* While going from top to bottom within any group one electronic shell gets added at a time.

* All the elements belonging to the same group have same valency.

* All the elements present in the same group have similar chemical properties.

Example : The elements beryllium, magnesium, calcium, strontium, barium and radium belongs to the group 2 so number of electrons in their outermost orbit are 2.

2. Periods and electronic configuration

* The horizontal rows in the modern periodic table are called as periods. There are 7 periods in the MPT.

* The period number indicates the number of cells in the atom of an element.

                             Period number = Number of Shells

* In a period while moving from left to right, the atomic number increases by one at the same time  the number of valence electrons also increases by one.

* In a period, there is radiation in properties of elements.

* The elements with the same number of shells belongs to the same period.

Example : Lithium, beryllium, boron, carbon, nitrogen, Oxygen, fluorine and neon has two shells in their atom so they belongs to second period.

* In a period, while going from left to right, the  atomic number increases by 1 at the same time atomic radius gradually decreases.

Periodic trends in the modern periodic table

The properties which show gradual variation in a group and in a period and are repeated after a certain interval of atomic number are called as periodic properties or trends.

The periodic properties are as follows:

1. Valency

2. Atomic size

3. Metallic- non Metallic character

1. Valency : 

The capacity of an element to combine with other element is called as valency.

* The valency of an element is determined by the number of  electrons present in the outermost shell.

* Elements belonging to the same group have same valency.

* In a period valency increases from 1 to 4 and then decreases from 4 to 0.

2. Atomic size :

* Atomic size is determined using atomic radius.

* Atomic radius is the distance between the nucleus and the outermost shell of an atom.

* In a period, atomic radius decreases from left to right.

   ( Explanation : In a period, while going from left to right the atomic number increases by 1 at the              same time the positive charge on the nucleus also increases by one unit. So the one more additional         electron gets added to the same outermost shell. So electrons experience greater pull from the                 nucleus.)

* In a group from top to bottom atomic radius increases because new shells are added to every next element.

 (Explanation : The distance between the outermost electron and the nucleus goes on increasing. As a result of this the atomic sizeincreases in spite of the increased nuclear charge.)

Note : atomic radius is expressed in picometre (pm)

3. Metallic -  non metallic character :

* Metals have a tendency to donate electrons so they are electropositive.

* Non metals have a tendency to accept the electrons so they are electronegative.

* In a period,  while moving from left to right metallic character decreases and non metallic character       increases.

* In a group,  from top to bottom metallic character increases because atomic size increases.

Zig-zag line in the modern periodic table (Borderline elements)

* A zig-zag line in the modern periodic table represents metalloids.

* This line in the modern periodic table separates metals from nonmetals.

* The elements which have the properties of both metals and nonmetals are called as metalloids.

Gradation in halogen family :

* The group 17 of modern periodic table contains members of halogen family.

* The general formula of halogen family is X2.

* A gradation is observed in their physical state down the group.

* The elements fluorine and chlorine are gases, bromine is a liquid while iodine is a solid.