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TNPSC BIOLOGY (ENGLISH) 

WHAT IS PLANT GROWTH AND DEVELOPMENT? WHY IT IS IMPORTANT?

Plant Growth and Development

✦ Increase in the size of living organisms is commonly called ‘growth’. Many physiological processes play an important role during the growth of plants and animals. In plants, seed germinates and develops into a seeding and later it assumes the shape of an adult plant. Plants show indefinite and diffuse growth while animals show fixed and uniform growth.

 

Types of Growth

✦ Primary and secondary growth – The mitotic division of meristematic cells present at the root and shoot apex increases the length of the plant body. This is called the primary growth. The secondary meristem increases the diameter of the plant body and it is called the secondary growth.

✦ Unlimited Growth – The root and the shoot system of plants growth continuously from germination stage to the death or throughout the life span of the plant. It is called ‘Unlimited’ or indeterminate’ type of growth. Limited growth – The leaves, fruits and flowers stop growing after attaining certain size. This is called ‘limited’ or ‘determinate’ type of growth.

✦ Vegetative growth – The earlier growth of plant producing leaves, stem and branches without flowers is called vegetative growth / phase.

✦ Reproductive growth – After the vegetative growth, plants produce flowers which is the reproductive part of the plant. This is called reproductive growth / phase.

✦ Development – Development is defined as sum total of growth and differentiation. Development is governed by both environmental and internal factors. One of the internal factors that regulate growth and development is ‘plant hormones’.

 

Control of Growth and Development

✦ Plant hormones / phytohormones / Growth regulators – plant hormones are chemically diverse substances produced in minute quantity and they involve in most of the plant cell activities. They regulate the growth process both by promoting and inhibiting growth. They are produced in certain parts of the plant and transported to other tissues where their action is shown.

✦ Auxins: Auxin was first isolated from human urine. The term ‘auxin’ is applied to the indole – 3 – acetic acid (IAA), and to other natural and synthetic compounds which have certain growth regulating properties. Auxins are usually produced by the growing apices. IAA and IBA (Indole Butyric Acid) Have been isolated form plants. Naphtahlene Acetic Acid (NAA) and 2,4 – D (2,4- dichlorophenoxyacetic) are synthetic auxins.

 

 

Functions of Auxins

✦ Auxins help to initiate rooting in stem cuttings. Auxins promote flowering. Apical Dominance: In most of the higher plants, the growing apical bud inhibits the growth of lateral buds. This phenomenon is called apical dominance.

✦ Auxins induce parthenocarpy, e.g., in tomatoes. Auxins are widely used as herbicides. Gibberelins: There are more than 100 gibberellins. They are denoted as GA1, GA2, GA3 and so on.

 

Functions of Gibberellins

✦ Gibberellins cause an increase in length of axis. They cause fruit elongation and also delay senescence. Thus, gibberellins can be helpful in keeping the fruits for a longer duration on tree. In brewing industry, GA3 is used to speed up the malting process.

✦ Spraying sugarcane crop with gibberellins increases the length of stem. This helps in increasing the yield by as much as 20 tonnes per acre.

✦ Cytokinins: Cytokinins have specific effects on cytokinesis. Kinetin was discovered from autoclaves of herring sperm DNA. Kinetin does not occur naturally in plants. Zeatin is a naturally occurring cytokinin which was isolated from corn – kernels and coconut milk.

✦ Ethylene: Ethylene is a simple gaseous PGR. It is synthesized in large amounts by tissues undergoing senescence and ripening fruits.

✦ Abscisic Acid: ABA is a plant growth inhibitor. It plays a major role in seed development, maturation and dormancy.

✦ Photoperiodism: Flowering in certain plants depends on a combination of light and dark exposures and also on the relative duration of light and dark periods. This response of plants is called photoperiodism.

✦ Flowering is an important step towards seed formation. Hence, photoperiodism plays an important role in plant evolution.

✦ Vernalization: In some plants, flowering is quantitatively or qualitatively dependent on exposure to low temperature. This phenomenon is called verbalization. Flowering is promoted during the period of low temperature because of vernalization.

 

Ductless Glands

✦ The word gland means having some secretions. There are two types ofglands

                  Endocrine gland - gland with duct

                  Endocrine gland - gland without duct

✦ The exocrine gland secretes enzymes which are important for digestion.The ductless or endocrine glands secretes hormones. They are special chemical substances that make wonder in our body

Pimple: A small papule or pastule .Pimples are sebaceous glands that areinfected by bacteria, become inflamed  and fill with pus.

 

Endocrine System in Man

✦ The chemical coordination of  the vital organs of the body processes to maintain thehomeostasisisthe work of endocrine system

✦ Endocrine system consists of a number of endocrine glands and theirhormones

Head               – a. Pitutary gland

                   b.pineal gland

Neck                – a. Thyroid gland

                    b. parathyroid gland

Thorax           – thymus gland

Abdomen      – a. pancreas - Islets of Langerhans

                   b. adrenal glands - adrenal cortex and adrenal medulla

                   c. gonads - testes in man and ovaries in women

Hormones

✦ Chemically hormones are proteins or amino acids or steroids.

 

Pituitary Gland   

✦ It is located just below the brain

✦ It is called as  the master gland because it secretes number of hormoneswhich control the functioning of all other glands.

✦ Your growth depends on the secretions of the pituitary gland

✦ ln adults, excess secretion leads to a condition called acromegaly.

✦ it is called as the conductor of endocrine orchestra.

✦ is differentiated into an anterior lobe  called adenohypophysis and a posterior lobe called neurohypophysis.

 

Hormones of adenohypophysis

Hormones of  neurohypophysis.

Somatotropic or Growth Harmone(STH or GH)

It brings forth gowthingeneral

Less production in children - dwarfism with retarded growth

Excess production in children - gigantism with excess growth

Excess  production in adolescents –acromegaly with large limbs and lower jaw

Tyrotrophic of Thyroid Stimulating harmone(TSH)

It stimulates the growth of thyroid gland and its production-the thyroxine

Adrenocorticotropic or Adrenal cortex stimulating hormone (ACTH)

It stimulates the adrenalcortex to produce the hormones aldosterone and cortisone

Follicle stimulating hormone (FSH)

It stimulates the maturation of graffian follicles (in the ovary)in the female ,to produce the eggs and sperm formation in the males

lLutenizing hormone (LH) in female or interstitial cell stimulating hormone (ICSH)in male

 

LH is female causes discharge of

female egg from graffian follicle - a

process, called ovulation and production of female sex hormone oestrogen and progesterone.

Lactogenic hormone(LTH)

It stimulates the growth of mammary glands in female and milk production after child birth


✦ The hormones of neuro Hypophysis namely, oxytocin and vasopressin are secreted by hypothalamus and are released on specific stimuli.

 

Hormones of Neurohypophysis

Functions and malfunctions

Oxytocin

It speeds up the child birth process, by stimulating the contraction and relaxation of the uterus in the female.

Vasopressin or Antidiuretic hormone (ADH

It helps in the reabsorption of water, producing concentrated urine in smallquantity.  It constricts the blood vessels and raises upthe blood pressure Less production of ADH results in diabetes insipidus, leading to production of excess of dilute urine

 

Thyroid gland

✦ It is located in the throat region.

✦ It secretes a hormone called thyroxine.

✦ The function of thyroxine is to control the rate of Metabolism, growth and respiration `

✦ The deficiency of thyroxine hormone in children is known as cretinism.

✦ Someiirnes the gland may enlarge causing a disease called'Goitre’

 

Pancreas

✦ Pancreas is both exocrine and endocrine. The endocrine part is called lslets of langerhans. lt has alpha and beta cells, which secretes glucagon and insulin.

✦ Deficiency of insulin in the body causes a disease known as diabetes mellitus.

 

Adrenal gland

✦ It secretes adrenalin hormone .This hormone  is produced during stress or emergency situations. It regulates  heart beat, breathing rate, blood pressure etc.

 

Tastes and ovaries

✦ Testes and ovaries secrete sex  hormones. Testes produce testosterone and ovaries produce oestrogen hormones

 

Role of Hormones in Reproduction

The following are the various reproductive phases in the life of a female.

1. Ovulation

2. Menstruation or the period

3. Pregnancy

4. Menopause

 

Sex Determination

✦ All the cells contain 23 pairs of chromosomes, the last pair of chromosome is different in males and females.

 

Sex chromosomes

✦ Sex chromosomes are of two types, these are names as X. and Ychromosomes. Usually a woman has two 'x' chromosomes (XX) and malehas one 'X' and one Y chromosome (XY), in their cells.

✦ During gamete (reproductive cell) formation the number of chromosomesis reduced into half. (46 chromosomes are reduced into 23).

✦ When a sperm containing 'X' chromosome fertilizes the egg, the zygotewill have two 'X' (XX) chromosomes. The zygote will develop into afemale child.

 

Pituitary gland

✦ It is called as the conductor of endocrine orchestra.

✦ is differentiated into an anterior lobe  called adenohypophysis and a posterior lobe called neurohypophysis.

 

Thyroid gland

The bilobed thyroid gland is located in the neck, one lobe on each sideof larynx, which secretes a hormone called thyroxine

 

Functions of thyroxine

✦ It increases the rate of metabolism

✦ It stimulata a rise in the body temperature

✦ It promo growth and differentiation of tissues.

✦ called personality hormone

 

Thyroid disorders

✦ Hypothyroidism- less secretion of thyroxine causes manyabnormalities  like simple goitre, myxoedema and cretinism.

✦ Simple goiter - It is due to the deficiency of iodine in our diet.

✦ Myxoedema - It is caused in the adults, the symptoms are, lowmetabolic rate, loss of mental and physical vigour, increase in weight.

✦ Cretinism - This is produced in children and the symptoms are stuntedgrowth, retarded mental development, defective teeth.

✦ Hyperthyroidism - The excess production of thyroxinecausesexophthalmic goiter or Grave’s disease.

 

The islets of Langerhans

✦ Pancreas is a dual role playing endocrine gland. The exocrine parts produce pancreatic juice. The endocrine portion is called islets of Langerhans.

✦ Alpha cells produce a hormone called glucagon and Beta cells produceinsulin and amylin.

 

Insulin

✦ It promotes the uptake of glucose by the cells for tissue oxidation

✦ It favours conversion of glucose,into glycogen and its  storage in theliver and the muscles.

✦ It prevents the formation of glucose from protein ad fat.

✦ It maintains normal blood glucose level at 80 - 120 mg/ 100 ml of blood.

 

Diabetes mellitus

✦ Less production of insulin causes diabetes mellitus, in which the excess unused glucose is excreted in the urine

 

Glucagon

✦ It is secreted when glucose  level in the blood is low.

 

Adrenal gland (Supra renal gland)

Adrenal cortex

✦ It secretes two hormones namely, Aldosterone and Cortisone

 

Aldosterone (Mineralocorticoid)

✦ It maintains mineral metabolism, by favouring reabsorption of sodiumand water and excretion of potassium and phosphate ions.

 

Cortisone (glucocorticoid)

✦ It stimulates the breakdown of glycogen into glucose raising the bloodglucose level.

 

Adrenal medulla

✦ It secretes two hormones, namely adrenaline- (epinephrine) and noradrenaline (norepinepthrine). They are together called emergencyhormones or hormones of flight and fight as they rapidly mobilize thebody to face as stress or emergency situation.

 

Testes

✦ The endocrine part secretes male sex hormone called testosterones (androgen).

✦ Testosterone stimulates the growth of reproductive organs and the production of male sex cell,the sperms

 

Ovaries

✦ Ovaries are both cytogenic (Producing egg cells) and endocrine (producing reproductive hormones ,such as oestrogen, progesteroneand relaxin0 in functioning

✦ Oestrogen is responsible for growth of female reproductive organs andthe appearance of secondary sexual characters in female, such as growth of public hairs, soft voice, feminine body, etc.,

✦ Progesterone maintains pregnancy and regulates menstrual cycle.

 

Parathyroid gland

These are found within thyroid and produce the hormones mainly parathormone and calcitonin which maintain the mineral metabolism.

 

Thymus gland

✦ It's a lymphoid mass, present above the heart. It secretes thymosin.

 

Pineal gland

✦ It lies under the corpus callosum in the brain. It produces melationin,causing concentration of pigments in some specific areas like areola,scrotal sacs

 

Heredity and Evolution

Father of Genetics: Gregor Mendel

Mendel’s laws of inheritance hybridization experiments on garden peas (Pisum sativum)

Mendel selected 7 pairs of true breeding pea varieties


Inheritance of one Gene

 

Monohybrid cross: A cross involving 2 plants differing in one character pair, e.g., Mendel crossed tall and dwarf pea plants to study the inheritance of one gene.

 

Monohybrid Phenotypic ratio: Tall : 3, Dwarf: 1=3:1

Monohybrid genotypic ratio: Homozygous tall (TT) : 1

Heterozygous tall (Tt): 2 & Homozygous dwarf (tt): 1 = 1:2:1

Mendel made similar observations for other pairs of traits and proposed that some factors were inherited from parent to offspring. Now it is called as genes.

 

Mendel’s Principles or Laws of Inheritance

1. First Law (Law of Dominance)

Characters are controlled by discrete units, called factors. Factors occur in pairs. In a dissimilar pair of factors, one member of the pair dominates (dominant) the other (recessive).

 

2. Second Law   (Law of Segregation)

“During gamete formation, the factors (alleles) of a character pair present in parents segregate from each other such that a gamete receives only one of the 2 factors”. Homozygous parent produces similar gametes. Heterozygous parent produces two kinds of gametes each having one allele with equal proportion.

 

The concept of dominance

In heterozygotes, there are dominant and recessive alleles. The normal (unmodified or functioning) allele of a gene produces a normal enzyme that is needed for the transformation of a substrate. The modified allele is responsible for production of

(i) The normal / less efficient enzyme or

(ii) A non – functional enzyme or

(iii) No enzyme at all

 

Inheritance of two Genes (Dihybrid cross)

Dihybrid corss: A cross between two parents differing in 2 pairs of contrasting characters.

Mendel made some dihybrid crosses.  E.g., Cross b/w pea plant with round shaped and yellow coloured seeds (RRYY) and wrinkled shaped & green coloured seeds (rryy).

Dihybrid Phenotypic ratio – Round yellow 9: Round green 3: Wrinkled yellow 3: Wrinkled green 1, i.e., 9:3:3:1.

 

Third Law (Mendel’s Law of Independent Assortment): It states that ‘when more than one pair of characters are involved in a cross – factor pairs independently segregate from the other pair of characters.

Thomas Hunt Morgan proved chromosomal theory of inheritance using fruit flies (Drosophila melanogaster).

 

It is the suitable material because,

1. It breeds very quickly

2. Short generation time (life cycle: 12 -14 days)

3. Breeding can be done throughout the year

4. Hundreds of progenies per mating

5. They can grow on simple synthetic medium.

6. Male and female flies are easily distinguishable.

7. It has many types of hereditary variations that can be seen with low power microscopes.

 

Sex Determination

Autosomes and sex chromosomes (allosomes)

1. Autosomes are chromosomes other than sex chromosomes. Number of autosomes is the same in males and females.

2. Sex chromosomes (X&Y) are the chromosomes which involve in sex determination.

3. Henking (1891) studied spermatogenesis in some insects and observed that 50 percent of sperm received a nuclear structure after spermatogenesis, whereas other 50 percent sperm did not receive it. Henking called this structure as the X body (later it is called as X – Chromosome).

 

Sex Determination in Humans (XX – XY type)

Human has 23 pairs of chromosomes (22 pairs are autosomes and 1 pair is sex chromosomes).

A pair of X – Chromosomes (XX) is present in the female, whereas X and Y chromosomes are present in male.

During spermatogenesis males produce 2 types of gametes, 50 percent with X – chromosome and 50 percent with Y – chromosome.

Females produce only ovum with an X – chromosomes.

There is an equal probability of fertilization of the ovum with the sperm carrying either X or Y chromosome.

 

Mutation

It is a sudden heritable change in DNA sequences resulting in changes in the genotype and the phenotype of an organism.

Frame – shift mutation: Loss (deletions) of gain (insertion/ duplication) of a DNA segment.

Point Mutation: Mutation due to change in a single base pair of DNA. E.g., sickle cell anemia.

Mutation results in Chromosomal abnormalities (aberrations). Chromosomal aberrations are seen in cancer cells.

Mutagens (agents which induce mutation) include,

1. Physical mutagens: UV radiation α, β, γ rays, X – rays etc.

2. Chemical mutagens: Mustard gas, phenol, formalin etc.

 

Variation

✦ Variation may be defined as the differences in the characteristics amongthe individuals of the same species (intra specific variation) or among the different genera (intergeneric variation) or different species (Interspecific Varation).

✦ No two individuals are identical to each other.

✦ Asexual reproduction thus results in off springs with minor variations.

 

Types of variations

✦ Somatic Variation - It pertains to body cells and it is not inherited.

✦ We often associate Darwin solely with the theory of evolution.

✦ Germinal Variation - It pertains to germ cells or gametes and it is inheritable. It leads to speciation and evolution.

 

Significance of Variation

✦ It is the source of raw material for evolution.

✦ Animals are able to adapt themselves to the changing environment

✦ Organisms are better suited to face the struggle for existence

✦ Variations give the organisms an individually of their own.

✦ Jean Bapdse Lamarck (1744-1829) postulated the Use and Disuse Theory.

✦ Lamarck quotes the example of development of long neck of Giraffe.

 

Theory of Natural Selection

✦ Charles Darwin put forth the law of natural selection involving struggle for existence and survival o the fittest.

 

Evolution

✦ Av Evolution may be defined as a gradual development of more complex species from pre-existing simple forms.

 

Speciation

✦ Thus speciation is arising of a new species from a sub-population of a species which is geographically or reproductively isolated over a long period of time from the other population of the same species.

 

Human Evolution

✦ First human like being - the hominid. The hominid was called Homohabilis.

✦ 1.5 million years ago with the rise of Homo erectus who were meateaters.

✦ The Neanderthal man who lived in East and Central Asia 1 million years ago.

✦ Archaic Homo sapiens arose in South Africa

✦ Between 75,000- 10,000 years, the modern Homo sapiens arose

 

Genetic Disorders

2 types: Mendelian disorders and Chromosomal disorders.

 

1. Mendelian Disorders

Caused by alteration or mutation in the single gene. The pattern of inheritance of Mendelian disorders can be traced in a family by the pedigree analysis. E.g., Haemophilia, Cystic fibrosis, Sickle – cell anaemia, Colour blindness, Phenylketonuria, Thalesmia, etc.

Mendelian disorders may be dominant or recessive.  By pedigree analysis one can easily understand whether the trait is dominant or recessive.

 

2. Chromosomal disorders

They are caused due to absence or excess or abnormal arrangement of one or more chromosomes. The Chromosomal disorders are of two types:

a) Aneuploidy: The gain or loss of chromosomes due to failure of segregation of chromatids during cell division.

b) Polyploidy (Euploidy): It is an increase in a whole set of chromosome due to failure of cytokinesis after telophase stage of cell division. This is often seen in plants.

Examples for chromosomal disorders

Down’s syndrome (Monogolism): It is the presence of an additional copy of chromosome number 21 (trisomy of 21).

Genetic constitution: 45 A + XX or 45 A + XY (i.e., 47 chromosomes).

 

Features

1. They are short statures with small round head

2. Broad flat face

3. Furrowed big tongue and partially open mouth

4. Palm is broad with characteristic palm crease

5. Retarded physical, psychomotor and mental development

6. Congenital heart disease.

Klinefelter’s Syndrome: It is the presence of an additional copy of X – Chromosome in male.

Genetice constitution: 44 A + XXY (i.e., 47 chromosomes).

 

Features:

1. Overall masculine development, however, the feminine development is also expressed. E.g., Development of breast (Gynaecomastia)

2. Sterile

3. Mentally retarded.

Turner’s syndrome: This is due to the absence of one of the X chromosomes in female.

Genetic Constitution: 44 A + X0 (i.e., 45 chromosomes).

 

Features:

1. Sterile, ovaries are rudimentary

2. Lack of other secondary sexual characters

3. Dwarf

4. Mentally retarded

 

Molecular Biology of the Gene

Nucleic acids (DNA & RNA) are the building blocks of genetic material.

1. DNA is the genetic material in most of the organisms.

2. RNA is the genetic material in some viruses. RNA mostly functions as messengers.

 

Structure of Polynucleotide Chain

Polynucleotides are the polymer of nucleotides. DNA & RNA are polynucleotides. A nucleotide has 3 components:

1. A nitrogenous base

2. A pentose sugar (ribose in RNA & deoxyribose in DNA)

3. A phosphate group

Nitrogen bases are 2 types

(i) Purines: It includes Adenine (A) and Guanine (G)

(ii) Pyrimidines: It includes Cytosine (C), Thymine (T-only in DNA) and Uracil (U-only in RNA).

Erwin Chargaff’s rule: In DNA, the proportion of A is equal to T and the proportion of G is equal to C.

Therefore, [A]+[G]=[T]+[C].

A nitrogenous base is linked to the pentose sugar through an N – glycosidic linkage.

Nitrogenous base + Pentose sugar = Nucleoside

Adenosine (deoxyadenosine)

Guanosine (dexoyguanisine)

Cytidine (dexoyguanosine)

Uridine (deoxythymidine)

Nitrogen base + sugar + phosphate group = Nucleotide (deoxyribonucleotide).

2 nucleotides are linked through 3’-5; phosphodiester bond à dinucleotide

More nucleotides à polynucleotide

 

RNA world

RNA was the first genetic material

Essential life processes (metabolism, translation, splicing, etc) evolved around RNA.

It acts as a genetic material and a catalyst.

DNA evolved from RNA for stability

 

Central Dogma of Molecular Biology Transcription

It is the process of copying genetic information from one strand of the DNA into RNA.

Here adenine pairs with uracil instead of thymine.

Both strands are not copied during transcription, beause

1. The code for protein is different in both strands. This complicates the translation.

2. If 2 RNA molecules are produced simultaneously this would be complimentary to each other, hence form a double stranded RNA. This prevents translation.

 

Types of RNA

mRNA (messenger RNA): Provide template for translation (protein synthesis).

rRNA (ribosomal RNA): Structural and catalytic role during translation. E.g., 23S rRNA in bacteria acts as ribozyme.

tRNA (transfer RNA or sRNA or soluble RNA): Brings amino acids for protein synthesis and reads the genetic code.

tRNA – the adapter molecule

 

Human Genome Project (HGP)

Genome: The entire DNA in the haploid set of chromosome of an organism.

In human genome, DNA is packed in 23 chromosomes.

Human Genome Project (1990 – 2003) is the first effort in identifying the sequence of nucleotides and mapping of all the genes in human genome.

Human genome contains about 3 x 109 bp.

 

Goals of HGP

1. Identify all the estimated genes in human DNA

2. Determine the sequences of the 3 billion chemical base pairs that make up human DNA

3. Store this information in database.

4. Improve tools for data analysis.

5. Transfer related technologies to other sectors.

6. Address the ethical, legal and social issues (ELSI) that may arise from the project.

Bioinformatics: Application of computer science and information technology to the field of biology and medicine. Usually applies in analyzing DNA sequence data.

 

DNA Fingerprinting (DNA Profiling)

The technique to identify the similarities of the DNA fragments of 2 individuals. Developed by Alec Jeffreys (1985).

 

Basis of DNA fingerprinting

DNA carries some non – coding sequences called repetitive sequence [variable number tandem repeats (VNTR)].

Number of repeats is specific from person to person. The size of VNTR varies in size from 0.1 to 20kb. Repetitive DNA are separated from bulk genomic DNA as different peaks during density gradient centrifugation.

The bulk DNA forms a major peak and the other small peaks are called as satellite DNA.

Satellite DNA is classified into many categories, (micro- satellites, mini – satellites, etc) based on base composition (A:T rich or G:C rich), length of segment and number of repetitive units.

An inheritable mutation observed in a population at high frequency is called DNA polymorphism (variation at genetic level).

Polymorphism is higher in non – coding DNA sequence. Because mutations in these sequences may not have any immediate effect in an individual’s reproductive ability.

These mutations accumulate generation after generation and cause polymorphism. For evolution and speciation, polymorphisms play an important role.

 

Application of DNA fingerprinting

Forensic tool solve paternity, rape, murder, etc.

For the diagnosis of genetic diseases

To determine phylogenetic status of animals

 

Genetic Engineering

Biotechnology is a process that used the scientific research on DNA for practical means. Biotechnology is synonymous with genetic engineering because the genes of an organism are changed during the process. Because the genes are changed. The DNA of the organism is said to be recombined. The result of the process is recombinant DNA. Recombinant DNA and biotechnology can be used to form proteins not normally produced in a cell to make drugs or vaccines or to promote human health.

An organism that contains additional genes from another organism is said to be transgenic.

 

Basic techniques in Genetic Engineering

✦ Restriction enzymes or Restriction endonucleases are molecular scissorswhich cut DNA at specific sites.

✦ DNA ligases are the paste enzyme which helps to join the broken DNA fragments.

 

Bio-Technology and Cloning

✦ There are several applications of Bio-technology such as brewing,industry, enzyme technology, manufacturing of anti-biotics, organicacids, vitamins, vaccines, steroids and monoclonal anti -bodies.

✦ It was Edward Jenner (1749-1823) in 1791 who coined the term vaccine

✦ Brewing Industry: Fermentatiuon  in alcoholic  beverages like beer, wine.

✦ Enzyme Technology:Enzymes are bio-catalysts that speed up reaction in cells.

✦ Many enzymes are utilized in the Pharmaceutical industry.

✦ Anti – Biotics:

✦ Organic Acids:Acetic acid is used for the production of vinegar

 

Development of Dolly

✦ Dolly was a cloned sheep, developed by Dr. lan Wilmut and hiscolleagues in Roselind Institute in Scotland in July 1996.

 

Vitamins: These are chemical compounds present in variable minutequantities in natural food stuffs.

✦ They do not furnish energy but are very essential for energy transformation and regulation of metabolism.

✦ Vaccines: Vaccines are substances that confer immunity against specificdisease. They act as antigens and stimulate the body to manufactureantibody.

 

Steroids: They are a type of derived lipids Ex: Cholesterol, containingsteroid drugs like prednisolone is produced from fungus Rhizopus.

Monoclonal anti-bodies: These are the anti bodies by cloned cells.Monoclonal anti - bodies, are now used for treatment of cancer.

 

Cloning:

✦ Cloning is an experimental technique wherein a group ofmorphologically and genetically identical organisms are produced.

✦ A clone may be defined as an exact carbon copies of a single parent. 

 

Types of clones

✦ Natural clones

✦ Induced clones

 

Stem Cell(Organ)Culture

✦ Unspecialized calls which have the  potentiality of growing and multiplying into enormous number  of same type of cells by repeated

✦ They can be introduced to become any other type of tissues with specific functions i.e

 

Types of Stem Cells

Embryonic Stem Cells: The embryonic stem cells can be derived fromearly embryo which is developed by "invitro fertilization" (fertilizationbe made artificially in the laboratory).

Adult or Somatic Stem Cells: They can grow, multiply and can bedifferentiated into same type of tissues into which they are implanted. The mechanism of adult or Somatic stem.

✦ The somatic stem cells are derived from sources such as bone marrow, embryos, amniotic fluid and umbilical cord.

 

Microbial Production

Vaccines: Killed or live germs suspension which is employed to induce the production of antibodies and bring forth immunity.

Antibiotics: Antibiotics are chemical substances derived from microbes like fungi, bacteria etc., employed to kill the infectious germs and cure a disease.

Vitamin B12 : Bio technologically synthesized vitamin B12 is used, to  cure pernicious anaemia.

Enzymes: Amylase is derived from amyloproteins of bacteria.

Insulin: Diabetes is treated by the biotechnologically produced insulin

 

Bio-Sensor and Bio-Chips

Bio sensor: It is a device consisting of immobilized layer of biological material such as  enzyme, antibody, hormone , nucleic acids, organelles or whole cells and its contact with a sensor

 

Bio-chips

✦ Biological Computers will be developed using bio-chips.Bio-chips will be useful in defense ,medicine ,etc.,

 

Gene Therapy

✦ Insulin dependent diabetes is neared with insulin injection.Insulin dependent diabetes is causedby the degeneration of beta cells due to a defective gene.

✦ Applying the principle of Bio-technology, it is possible to correct the defective gene. When the defective gene is corrected with a new genethe genetic defect developed is, rectified and cured. It can be used to treat defects in Somatic i.e (body) or Gametic (sperm or eggs) Cell.

 

Types of Gene Therapy

Somatic gene therapy- The genome (gene set) of the recipient ischanged.

Germ line gene therapy- Egg and sperm of the parents are changed,for the purpose of passing the changes to the next generation

 

 

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