TYPES OF NATURAL SELECTION

Natural selection occurs with or without environmental change .

1- Directional natural selection - This occurs when natural selection favours one with continuous variation e.g. crabs will be less able to pray upon thicker shelled oysters than thinner shelled oysters .

2- Stabilizing selection - It occurs when natural selection favours the intermediate state of continuous variation , overtime the intermediate colour of an oyster become more common and the extreme variation become less common or lot.

3- Disruptive selection - It occurs when natural selection favours both extremes of continuous variation .

4- Kin selection - Kin selection occurs when natural selection favours a trait that benefits related members of a group . Altruistic behaviours are a result of kin selection e.g. sterile workers bees serve the fertile queen to produce a large number of offsprings .

5- Sexual selection - Natural selection favours the traits that maximize the ability of an individual to compete and attracting mates. This is called sexual selection .

6- Sexual dimorphism - Sexual dimorphism is when males look different then females of the species .

7- Male-male competition - In species with males that battles over right to mate with females such as elephants , deers ,etc . The male that win a fight because he is the strongest and most dominant.  

ADAPTIVE RADIATION

The process of evolution of different species in a given geographical area starting from a point and literally radiating to other areas of geography is called adaptive radiation .

Small black birds later called Darwin's finches were original seed-eating features , later many other forms with altered beaks arose, enabling them to become insectivorous and vegetarian finches.

Another example is Australian marsupials . A number of marsupials each different from the other evolved from an ancestral stock , but all within the Australian island continent .

When more than one adaptive radiations appeared to have occurred in an isolated geographical area one can call this convergent evolution .

Placental mammals in Australia also exhibit adaptive radiation in evolving into varieties of such placental mammals each of which appears to be similar to a corresponding marsupial .  

HARDY-WEINBERG 'S PRINCIPLE

Hardy-Weinberg's principle  gives the geneticists a tool to determine when evolution is occuring .

Population geneticists use  Hardy-Weinberg's principle to calculate a staring point allele frequency and than compare it to frequencies measured at some future time .

Hardy-Weinberg's principle use the bionomical expression p square+ 2pq + q square = 2 to calculate the genotypic and allele frequency of a population. 

HUMAN EVOLUTION

Human beings are evolved 1 million years ago . It is proved by fossil records .

1- Parapithecus - It is an oligocene fossil . It was excavated from Fayum province of Egypt . The animal has size of squirrel . It is believed to the ancestors of old monkey .

2- Aegyptopithecus - It is also a fossil from Egypt . It is larger in size . It is considered as forerunners of dryoithecus .

3- Dryopithecus - It is a myocene fossil . It is common ancestors to human and ape .

4- Ramapithecus - It is a fossil of later miocene and pliocene epoch. It  was an earliest man like primate . The fossil is reported from Africa .

5- Austalopithecus - It is commonly called southern ape or first man ape . It is evolved about 1-4 million years ago . Brain size is larged than body size . It was excavated from lime stone of Africa .

6- Homohabilus - It is an early true man . It had bipedal locomotion . It is the stone tool maker .

7- Homoerecttus - It evolved about 0.25 - 1.7 million years ago . It walked erect over long legs . It used stone and bone tools , fire, etc e. g. Java man .

 8- Homo sapiens - It is evolved from homo erectus in Africa about 5 lakh years ago . It includes Neanderthal man Cro-mangnon    

BIOLOGICAL EVOLUTION

Evolution by natural selection probably started when cellular forms of life with minor differences in metabolic capability originated on the earth .

The essence of Darwinian theory about evolution is natural selection .The rate of appearance of new forms is linked to the life cycle or the lifespan .

Microbes that divide fast produce thousands of next generation show evolution and appearance of nw variants or even species much faster .

For the same thing to happen in a fish or frog of humans would take million of years as lifespans of these animals are in years .

Nature selects the fittest . Fittest are the individuals that are better adapted to survive in an otherwise hostile environment .

Adaptive ability is inherited . It has a genetic basis . Fitness is the end result of the ability to adapt and get selected by nature. 

TRANSCRIPTION UNIT OF GENE

A gene is a part of DNA which stores information to make an RNA or a protein .

Cistron is a segment of DNA which codes for a polypeptide chain .

The structural gene that has one transcription unit , it is called monocistronic .

The structural gene that has make transcription unit , it is called polycistronic .

The monocistronic structural genes have interrupted coding sequences in eukaryotes .

The coding sequence is called exons and the non coding or intervening sequences are called introns .

The introns do not appear in the final product of mRNA . 

TRANSCRIPTION UNIT

A transcription of DNA consists of 3 parts ;

a promoter , structural gene  and a terminator .

The enzyme that polymerize the RNA chain is DNA dependent RNA polymerase .

The DNA strand that has polarity 3'  to 5' acts as a template .

The other strand which do not code for anything is called coding strand .

The sigma factor initiates transcription of the RNA chain .

The RNA chain grows from 5' to 3' end .

The RNA chain is terminated by a protein called rho factor .

ELONGATION

 Transfer of amino acids to specific tRNA  already present in cytoplasm .

Association of ribosome with first codon on the mRNA .

Attachment of first tRNA carrying the first amino acid of the protein to be formed to the first codon .

Movement of the ribosome on to the second codon along the mRNA .

This is called translation .

Attachment of second tRNA carrying the second amino acid to the second codon and release of first one along with formation of a dipeptide on the second tRNA by the help enzymes and the elongation factor.

COSMIDS

These are the vectors which can accommodate DNA segments up to 45 kbp . 

These are actually plasmid particles to which specific DNA sequences, namely those for the cos sites are inserted .

Since the cos sites enable the DNA to be packed in the phage particle so we can say that cosmids allow the packaging of DNA in phage in vitro thus permitting their purification .

Like plasmids these cosmids these cosmids also perpetuate in bacteria .

The advantage of cosmids for cloning is that its efficiency is high enough to produce a complete genome library of 10 to the power 6 - 10 to the power 7 clones from a mere 1gm of insert DNA . 

The disadvantage is its inability to accept more then 40-50 kbp of DNA.  

ISOLATION OF GENE OF INTEREST

 The fragments of DNA  are separated by a technique called gel electrophoresis .

The DNA is cut into fragments by restriction endonucleases .

These fragments are separated by a technique called gel electrophoresis .

Agarose a natural polymer obtained from sea weeds is used as the matrix .

DNA fragments being negatively charged are separately by forcing them to move through the matrix towards the anode under an electric field .

The DNA  fragments separate according to their size .

The separated molecules are stained by ethidium bromide and visualised by exposure to UV radiation as bright orange coloured bands .

The separated bands of DNA are cut from the gel and extracted from the gel piece .

Such DNA fragments are purified and used for constructing recombinant DNA by joining them with cloning vectors . 

COMMUNICABLE DISEASES

It is transmitted from one person to another by means of contact , water , air , food or through animals .

They are of  five types 

1- Viral diseases 

It diseases caused by virus .

Example- Influenza , Common cold , Poliomyelitis , Measles , Mumps , Chickenpox , Dengue fever , Yellow fever, AIDS .

2 - Bacterial diseases 

It diseases caused by bacteria .

Example - Gonorrhoea , Tetanus , Anthrax , Botulism , Typhoid , Cholera 

3- Protozoan diseases 

It diseases caused by protozoans .

Example - Malaria , Amoebiosis  etc .

4- Fungal disease 

It disease caused by fungus .

Example - Ringworms 

5- Helminthes  disease 

It disease caused by helminthes .

Example- Ascariasis and Filariasis. 

PEST RESISTANCE PLANTS

Pest resistance plants have been created to protect against the nematodes .

The nematode Meloidogyne  incognitia infects the roots of the tobacco plant causing great loss in the production of the tobacco .

Thus a technique is being developed to protect the tobacco roots known as the RNAi or RNA interference.

RNAi takes place in all eukaryotic organs as a method of cellular defence .

This mechanism involves the silencing of the specific mRNA so that the protein synthesis or the gene expression will be prevented .

In this mechanism the nematode specific gene i. e. ds DNA and introduced into the host plants .

These ds DNA synthesizes the ds RNA in the host cells .Then the ds RNA are cleaved into  si RNA , sh RNA and mi RNA by the enzyme DICER .

Whenever the nematode tries to infest the roots of the tobacco plant the fragments of ds RNA binds with the specific mRNA of the nematode to form the compound called RISC .

Thus the formation of RISC dose not allow the translation of mRNA o nematodes for root destruction . As a result the nematode can not destroy the root. 

SIGMA FACTOR

 Protein in synthesis in initiated  by initiation factors . There are three initiation factors in prokaryotes like IF1, IF2 , IF3 similarly eukaryotes there are nine initiation factors like elF1 , elF2 , elF3 etc . 

Ribosomes are scattered in cytoplasm as separated units .That means both the sub units are detached from each other .

elF2 or elF3 gets attached to the smaller subunits are assembled from 80s ribosome in eukaryotes and 70s ribosome in prokaryotes . 

The larger subunit of ribosome has 3 rites 

These are p- site peptidyl site

A site - aminoacyl site and

E site - exit site 

The first amino acid tRNA complex gets attached to the p site i.e. AUG known as initiation codon .

Th first amino acid formed in the process of translation is fermylated methionine incase of prokaryotes where as methionine in eukaryotes . 

ENZYME INVOLVED IN DNA REPLICATION

 ENZYME                       FUNCTION IN REPLICATION 

1- Topoisomerase   -  Initiation of unwinding of helix . It detangles the coils and super coils .

2 - Helicase            - Breaks the hydrogen bonds between two stranded DNA becomes single stranded. 

3 - Single stranded- These bind to the single strands of DNA to prevent hydrogen bonding and  reforming       binding proteins  of  duplex .

4 - DNA polymerases- DNA pol-III addition of nucleotides to the newly synthesized DNA strand  DNA                                            pol-I proof freading .

5 - Primase                 - Synthesis of primer .

6 - DNA ligase          - Joins the DNA by forming phosphodiester bond .

       

NON-ENDOSPERMIC SEED

When the endosperms is completely eaten up by the growing embryo such type of seed is called non-endospermic seed.

Example - Pea , Gram , Bean , Groundnut etc

In non- endospermic seed the food is stored in the cotyledons .

The nucellus is generally used up by the developing embryo but in same seeds it persists in the form of a thin layer around the endosperm . 

This residual nucellus is known as peri sperm .

Example- Castor , Black pepper , water lily etc 

The outer integument from the outer hard dovering of seed i.e. the testa where as the inner integument forms the inner then coating of seed called as tegmen .

A scar left on one side of the seed is called as hilum .

It is the point of attachment of the funicle to the seed .

The micropyle of the integument remain as a small pore and function as an opening of the seed for the entry of water and oxygen during germination .

The final step of development of seed is the significant decrease in its water content which causes reduction in metabolic activities and lead to seed dormancy .

Seed germination is promoted by Gibberellin in hibited by ABA  

SIGNIFICATION OF SEED FORMATION

 Seed can be used as food throughout  the year and also helps in raising the crop next year .

Seeds store enough food material in endosperm or in the cotyledons to nourish the seedlings .

Seed are the product of sexual reproduction which show mixing of genetic material and variation .

They are able to tolerate low and high temperature .

Seeds remain dormant to survive unfavourable condition and are able to germinate during favourable condition .

In comparison with spore the seeds are usually transformed into seedling faster due to the availablity of the larger food reserves in them .

ADVANTAGE AND DISADVANTAGES OF CROSS POLLINATION

Advantages;

Cross pollination leads to cross fertilization in plants . It brings about genetic recombination and introduced the variations in the offspring .

New and improved varieties of plants can be obtained by this technique due to the combination of characters of two different plants .

Plants obtained through cross-pollination are more resistance to disease and unfavourable condition .

It produced numbers seeds of better qualities and high viability .

It helps in the process of evolution .

New or improved varieties of plants are produce .

Disadvantages ;

Cross pollination is not a sure method as chance factor is always there .

It is a highly wasteful method as plants have to produce large no of pollen grains  .

There is considerable wastage of pollen grains especially in wind pollinated flower .

It is less economical as the plants have to develop many devices to bring about this kind of pollination through various agencies .

It is less as the plants have to develop many devices to bring about this .

Some of the very good traits of the race are likely to be lose during recombination .

There are chances of the entry of some harmful and undesirable traits in the plants .Which may persist in the race for ever .

ADVANTAGE AND DISADVANTAGES OF SELF POLLINATION

Advantage ;

Self pollination maintains the parental characters .

It is used to maintain pure lines for hybridization  experiment .

It ensured seed production .

Flowers do not develop devices for attracting insect pollinators .

It eliminates some unwanted recessive characters .

Disadvantages ;

New useful characters are rarely introduced .

Immunity to diseases decrease.

Variability is not seen so adaptability to changed environment are reduced .

Vigour and vitality of the race decreases with prolonged self pollination . 

PROCESS OF RECOMBINANT DNA TECHNOLOGY

The process of recombinant DNA technology involves ;

I- Isolation of genetic material

The gene of interest is isolated from the cells by using the enzymes lysing as it dissolved the plasma membrane of the cell.

II- Cutting of the genetic material at specific site 

The desired gene or the gene of interest is then cut into specific site with the help of the enzyme the restriction endonucleases .These enzymes cut the DNA segment forming sticky ends .

III- Formation of recombinant DNA 

Then the gene of interest is inserted into the plasmid vector with the help of the enzyme DNA ligase . After insertion they are called as the recombinant DNA .

IV- Transformation of the recombinant DNA into the competent host 

The recombinant DNA is then transformed into the host or competent  host cells . 

Here the plasmid DNA replicates independently along with the genetic material of the host .

This results in the formation of multiple copies of the desired DNA or gene . 

CLONING VECTORS

Vectors are the DNA molecules that carry the gene of interest to be inserted into the host organism .

Example- plasmid 

The plasmid is an autonomously replicating extra chromosomal genetic content present in the bacteria . 

It is different from the chromosomal DNA .

The feature that's are required in a tipical cloning vector are origin of replication  selectable marker cloning site .

Following featured are required for a cloning vector .

Origin of replication known as ori . This is important for replication with in the host cell as well as to maintain the copy number .

Selectable marker to identify transformed cells .

Trans formed cell same those cells which contain gene of interest .

Cloning site - Another important feature of the cloning vector is the presence of specific restriction sites where the enzyme restriction endonucleases make a cut so that a foreign DNA segment may be introduced to the vector . 

OVUM

 Ovum is the female gamate of human being .

Ovum is round shaped and can not be divided into parts parts .

These are produced in the ovary .

Ovums are non-motile .

It contains only X  chromosomes .

Centriols are absent in ovum .

SPERM

Sperm is the male gamate of human beings .

Sperm can be divided into head , neck , middle piece and tail .

These are produced in the testes .

Sperms are motile .

It contains either X or Y chromosomes .

Centriols are are present in sperm . 

 

CONTICAL REACTION

Immediately after of a sperm into the egg the latter shows a cortical reaction to check the entry of more sperms .

It this reaction the cortical granules present beneath the eggs plasma membrane release chemical substance between the ooplasm and the olasma membrane .

These substances raise the vitelline membrane above the egg surface .

The elevated vitelline membrane is called fertilization membrane .

The increased space between the ooplasm and the fertilization membrane and the chemical present in it effectively chech the entry of other sperm .   

PENETRATION OF SPERM

The ovum secretes a chemical substance called fertilization and the sperm secretes a protein called antifertilizin .

This fertilizin - antifertilizin interaction causes agglutination of egg and sperm .

The sperm generally comes in contact with ovum in the animal pole .

Ovulation in the human female occurs at secondary oocyte stage in which meiosis -I have been completed and first polar body has been released but second maturation is yet to complete .

Penetration of sperm is a chemical mechanism .

In this acrosome of sperm undergoes acrosomal reaction and releases certain sperm lysins which dissolve the egg envelopes locally and make the path for the penetration of sperm .

These sperm lysins contain a  lysing enzyme hyaluronidase which dissolves the hyaluronic acid polymers in the intercellular spaces which holds the granulose cells  of corona radiata together , corona penetrating enzyme and acrosin .

Then it dissolves the zona pellucida .

Only sperm nucleus and middle piece enter the ovum . The tail is lost .

BT- COTTON

BT stands for a bacterium Bacillus thuringensis . These bacteria secretes a toxic protein in crystals which kills the different pests .

The toxic crystals are in the form of protoxin .

These protoxins are inserted into the cotton plants by the process of recombinant DNA technology .

When the pests try eat the leaves of the cotton plants the protoxin is converted into the toxin as a result the toxin creates holes or pores in epithelial cells of the gut of the pests leading to the death of the pests .

The BT toxin are coded by a gene named cry .

Different cry  cry IIAb toxins are used to kill the corn borer . 

TRANSGNIC ANIMALS

The animals which carry foreign genes are called transgenic animals .

These animals after receiving foreign genes produce highly valuable materials .

The foreign gene are inserted into the genome of the animals using EDT .

Advantages and utilities of transgenic animals ;

Transgenic animals are made to synthesize biological products .

Transgenic animals are used to study normal physiology and development .

These are used to test the vaccines safety.

These are used for chemical safety testing .

These are used to study diseases .

These are used for growing sparate .

Used for replacement of defective parts .

Used for production of clones.

   

BLASTOCYST FORMATION

About the time morula enters the uterine cavity fluid begins to penetrate through the zona pellucida into the intercellular spaces of the inner cell mass .

Gradually the intercellular spaces becomes confluent and finally a single cavity the blastocoel forms .

At this time the embryo is a blastocyst.

The cells of the inner cell mass now called the embryoblast are at one pole and those of the outer cell mass or trophoblast flattens and forms the epithelial wall of the blastocyst .

The zona pellucida has disappeared allowing implantation to begin .  

LACTION

Production of milk in the mammary gland is called lactation .

Lactation comprises of two phases, lactogenesis and galactopoiesis .

Ducts in the mammary glands develop after puberty . Under the influence of estrogens growth hormones and adrenal glucocorticoids .

During pregnancy the mammary glands enlarge and alveoli develop in response to increasing levels of estrogens growth hormone adrenal glucocorticoids .

Insulin progesterone and from the placenta somatomammotropin .

The secretion and storage of milk takes place under the influence of hormone prolactin .

And the ejection of milk is stimulated by the hormone oxytocin .

The first milk which comes from the mammary glands of the mother just after child birth for 2-3 days is called colostrum .

Colostrum contains large numbers of antibodies called secretory immunoglobulin i.e. IgA that help protect the mucous membranes in the throat lungs and intestines of the infant .

Colostrum is also high in carbohydrates high in protein and low in fat .

The main constituents of breast milk are fat casein lactose , mineral salts and vitamines .   

GASTRULATION

It also called formation of three germ layer .

Transformation of blastula or blastocyst into gastrula is called gastrulation  .

During gastrulation the cells of the inner cell mass move to their final destination to form three germ layer ectoderm, mesoderm and endoderm .

The movement of inner cell of inner cell mass is called morphogenetic movement .

During gastrulation a cavity is formed known as archenteron with an opening called blastopore .

Each germ layers gives rise to specific tissue organs and organ systems .

SURGICAL METHOD OF BIRTH CONTROL

Surgical methods also called sterilization are generally advised for the mole or female partner as a terminal method to prevent any more pregnant.

Surgical intervention blocks gamete transport and there by prevent conception .

Sterilizatilon  procedure in the male is called vasectomy .In vasectomy a small part of the vas deferens is removed or tied up through a small incision on the scrotum .

Sterilization  in the female is called tubectomy .In tubectomy a small part of the fallopian tube is removed or tied up through a small incision in the abdomen or through vagina .

These techniques are highly effective but their reversibility is very poor . 

ORAL CONTRACEPTIVE PILLS

These are the hormonal pills used by females in the form of tablets .

 Birth control pills stop the ovaries from releasing eggs and thickens the cervical mucus which keeps sperm from fertilizing the egg .

 The birth control pills pills come in two forms combination pills contain two hormones progestin and estrogen while the mini pills contain only progestin .

COMBINED PILLS 

When taken correctly the pill is over 99percent effective at preventing pregnancy .This means that fewer than one woman is 100 who use the combined pill as contraception will get pregnant in one year .

The usual way to take the pill is to take one every day for 21 days then stop for seven days and during this week there will have a period type bleed .Then the women need to start taking the pill again after seven days .

The women need to take the pill at around the same time every day otherwise she could get pregnant if she doesn't do this or if she misses a pill or vomit or have severe diarrhoea .

The combined pill is not suitable for  women over 35 who smoke or women with certain medical condition. 

The pills prevents the ovaries from releasing an egg each month .

The pills thickens the mucus in the neck of the womb so it is harder for sperm to penetrate the womb and reach an egg .

The pills make thin the lining of the womb .So there is less chance of a fertilized egg implanting into the womb and being able to grow .

There are many different brands of pill mode up of three main types 

Monophasic 21 -day pills , Phasic 21-day pills , Every day pills ,etc

   

 

IUCDs or IUDS

IUDS is stand for Intra Uterine Contraceptive Devices .

An intra uterine device is an effective safe long acting cost effective contraceptive method used in many countries .

It consists of a small flexible plastic device inserted into a woman's uterus and is left in place for long periods of time providing continuous protection against pregnancy for a minimum of 10 years .

IUCDs increase the phagocytosis of sperm in uterus and copper reduce the motility and fertility capacity of sperm .

The hormone releasing IUCDs make the uterus unsuitable for implantation and the cervix hostile to the sperms . There are three different types of IUCD's .

I- Copper Bearing IUCDs 

Which are made of plastic with copper sleeves and copper wire on the plastic such as Tcu- 380A and MIcu -375 .

II- Hormone Releasing IUCDs 

These are made up of plastic and steadily release small amounts of progesterone or other progestin hormones .Such as LNG 20 and progesterone .

III- Inert or Unmedicated IUCDs 

These are made of plastic or stainless steel only .

Such as lippes loop and chinese stainless steel ring .

   

2- BARRIER METHOD OF BIRTH CONTROL

These methods appear to be mechanical ones and they helps in preventing the deposition of sperms of male into the vagina of the female and finally their passage into the uterus .

The devices used in barrier methods are 

I- Condom 

A sheath made of latex rubber , plastic or silk that is fitted over the penis during sexual intercourse .

II- Diaphragms , Cervical caps and  Vaults

These are the barriers made up of rubber . These are inserted into the female  genital tract to cover the cervix during copulation .

III- Femidom 

It is a flexible female condom . It consists of a loose fitting sheath and two rings . One polyurethane ring remains outside the vagina and is a guide for insertion of penis . 

1- NATURAL METHODS OF BIRTH CONTROL

Such methods do not require any device or medicine . It simply works on the principle of avoiding changes of ovum and sperm meeting . This is of following there types 

I- Rhythmic Method or Periodic Abstinence 

 In this the couples avoid or abstain from coitus from 10th to 17th day of menstrual cycle as chances of fertilization are very high during this period because ovulation occurs .

II- With Drawl Method 

It which the penis is with drawn from the vagina before ejaculation .

Thus if insemination is avoided then there is no chance of pregnancy .

III- Lactational Amenorrhea Method 

It is based on the fact that just after the delivery of the baby there is no menstruation and is treated as the phase of intense lactation .

Therefore as long as breast feeding of the baby continues there is no chance of conception .

The lactational amenorrhea method is known to be effective only up to a period of six months after parturition .

 

CAUSES OF OVER POPULATION

Lack of education about the reproduction and family panning .

Improved quality of life of people increased health facilities and better living condition have an explosive impact on explosion of population .

Rapid decline in death rate MMR .

Decrease in IMR .

Increase in population of reproductive age .  

SHORT NOTE ON SAHELI

Central Drug Research Institute , Lucknow , has developed non-hormonal contraceptive pill.

Ormeloxifene also known as centchroman  is one of the selection estrogen receptor modulator or SERMs a class of medication  which acts on the estrogen receptor .

It is best known as non-steroidal oral contraceptive which is taken once per week , In India ormeloxifene has been valuable  as birth control since the early 1990s and it is currently marketed there under the trade name saheli .

Ormeloxifene  has also been licensed under the trade names novexds centron and sevistu .

EFFECT OF OVER POPULATION

Out of the entire human population in India i.e. about 1.22 billion nearly one third are young ranging in age  group of 15-25 and majority of them experince the constrains in making their life choices .Few of them experience risky or unwanted sexual activity and there fore face adverse reproductive health out comes .

Some times such young people are represent to be HIV positive . Many of female death cases are due to complications of pregnancy , childbirth and abortions .

In order to maintain a good reproductive health , India was the first to take up the national family planning programme which was launched in 1951 and this was the warld 's first governmental population stabilization programme . By 1996 the programme was estimated to have prevented about 170 million births .

There fore following the recommendation of international conference on population and development , the government of India introduced the reproductive and child health package to supplement the matermal and child health services in the country .

These programmes where taken up in order to create awareness among the people for building up a reproductively healthy society .

Different government and non-government organizations also took up certain steps to apprise the people about the different reproductive related aspects .

For implementation of different action plans in order to attain a good reproductive health advice of the professionals infrastructural facilities and meterial support are essential .

These facilities can provide medical care to people facing different reproductive related problems at the time of pregnancy delivery abortion , contraception  and so on .

Few programmes have been undertaken by government to provide fucilities which include family planning child immunization etc .

REPRODUCTIVE HEALTH-I

Problems and strategies ;

According to world health organization reproductive health is a total well being in all aspect of reproduction i.e. physical , emotional , behavioral  and social . India initiated reproductive health programme in 1951 .

Wider reproduction related areas are currently in operation under the reproductive and child health care programme . It helps to give awareness to people about reproduction related .

Aspects and to create a reproductive healthy society.  

APICULTURE - Bee keeping

Apiculture or bee keeping is the care and management of honey bees for production of honey and th wax .

The place where a lot of beehives are placed for culture is called apiaries  .

Apiaries can be set up in areas where are sufficient bee pastures usually areas that have flowering plants .

Common varieties of bees in India 

1- Apis dorsata - It is also known as rock bee . It is agiant bee and produced about 38 to 40 kg of honey per  colony .These bees are aggressive and  migratory .

2- Apis indica - It is also known as Indian bee .It can be easily 

MOOD DISORDER

Changes in mood that interfere with every day life is called as mood disorder .

It may be due to failure of examination death of near relatives losing a job and facing interviews etc .

Example - Depression , Biopolar disorder

Attention deficit or Hyperactivity disorder

It is a mental disorder characterized by difficulty paying attention , keeping up with assignments , following instructions and social interactions .

Children with ADD may appear to be  bored or disinterested in class room activities .

These children are mostly disliked by the others .

BODER LINE PRESONALITY DISORDER 

It is a type of unstable personality disorder.

The person with BDP has difficulties with how they think and feel about themselves and other people .

The BPD patients experiences the following things 

Fell very worried about people abandoning himorher .

Very intense emotions that lasts from a few hours to a few days and can change quickly .

Low self -esteem .

Find it very herd to make and keep stable relationships .

Act impulsively .

Self harm or have suicidal feelings anger .

 

MANIC DEPRESSION OR BIPOLAR DISORDER

Bipolar disorder is a mental disorder characterized by wide mood swing from high to low .

Periods of high or irritable mood are called manic episodes . In this the person becomes vary active but in a unproductive way.

For example - Spending more money than is wise or gatting involved sexual adventures that are regretted later .

Biopolar depression can be much more distressing than mania and because the risk or suicide is potentiallyb more dangerous .

BIOPIRACY

Biopiracy is theft or robbery of biological entities or thir products from a country with patent right .

Exploitation of biological resources or their products without proper authorisation from the concerned country is called biopiracy .

Th main purpose of biopiracy is unlawful high economic gain .

Examples of biopiracy 

1- Biopiracy of African super sweet berries 

 Pentadiplandra brazzein is a plant found in the west of south Africa . It is a vital source of protein known as Brazzein . Here , people use it as a low calori sweetener .It is known to be two thousand times sweeter then sugar .Recent developments includes isolation of the gene encoding brazzein that has been equenced and patented in the USE .

2- Patenting of Azadiracta indica Neem since ancient times neem has proved to be useful in several ways . Indians have shared their knowledge regarding neem across the globe .In the year 1994 US department of agriculture and an american company - W.R. Grace riceved a European patent that included various methods that are used for controlling fungal infection  in plants by using a composition extracted from neem .

3- Biopiracy of the Enola bean - It was named after the wife of Larry proctor , who patented it  in 1999 .Enola bean is a variety of Mexican yellow bean . Farmers in North Mexico depended on sales of this bean .The patent holder subsequently side a large number of importers of Mexican yellow beans .As a result it caused an economic damage to farmers .A lawsuit was filed by farmers and the result was in farmers as ruled by U.S. patent and trademark office .

4- The rose Periwinkle - The rosy periwinkle was originally found in Madagascar  Now , it has been introduced to several other tropical countries across the globe .This implements that researchers can obtain know ledge from one nation and plant samples in other nation .

  

ANTIGEN

An antigen is any substance that elicits an immune response and is then capable of binding to the subsequently produced antibodies .

Antigens are generally protins or polysaccharides but other substances such as nucleic acid can also be antigens .

Antigens in tissues bind antibodies at different cell sites the membrane ,cytoplasm ,nucleus , organelles or a combination of more then one .

Many compounds are antigenic , Because of their large size proteins are ideal for immunization and for binding but polymers can also be antigenic .

The most common antigen that induce antibody production are bacteria and viruses.  

PARTURITION OR BIRTH

 The process of giving birth to the young one is known as parturition .

A developing foetus secretes hormones  from its adrenal glands . These hormones diffuse into the maternal blood and accumulate to stimulate the release of oxytocin from the mother's posterior pituitary gland .

Oxytocin causes the forceful contraction of smooth muscles of myometrium called labour pains .The foetal membranes burst and amniotic fluid is released but foetal membrane remain behind .This labour pain pushes the young gradually out through the dilated cervix and vagina with the head foremost .

It is aided by a reflex and voluntary contraction of abdominal   muscles .

In the beginning the labour pain occurs once every half or quarter of an hour but soon becomes more frequent .

It is followed by the expulsion of the umbical cord placenta and foetal membranes after birth .

Sometimes the foetus fails to come out then the body is delivered by surgical procedure .Such a baby' called caesarean .

Relaxin - It causes widening of pelvis by relaxing the public symphysis of the pelvicgirdle.

TURNER'S SYNDROME

Turner syndrome was first discovered by Dr. Henry Turner in 1938 .

This is a sex chromosomal genetic disorder is due to the loss of a X-chromosomes resulting in a karyotype 44AA + XO .

The Turner syndrome occurs in two ways 

I- When an abnormal ovum containing no sex chromosome 22+0 fertilize with normal sperm 22+X results in the turner's syndrome .

II- When an abnormal ovum containing no sex chromosome 22+ 0 fertilizes  with normal ovum 22+ X results in the turner's syndrome .

They are sterile female having the symptoms low stature ,webbed neck ,under developed breast ,rudimentary gonads, and lack of menstrual cycle during puberty.

KLINEFELTERS SYNDROME

This syndrome was first discovered by H.F. Klinefelter in the year 1942.

This genetic disorder is due to the presence of an additional copy of the X-chromosome .

This is a sex chromosomal disorder which may inherited in two ways .

I- When a normal ovum containing 22+X fertilizes with abnormal sperm 22+XY .

II- When a normal sperm containing 22+Y fertilizes with  abnormal ovum 22+XX . Then Klinefelter's syndrome occurs .

Persons with this syndrome have 47 chromosomes .

They are usually sterile males , tall , obese with long limbs , high pitched voice ,under developed genetalia and have feeble breast development.

POST TRANSCRIPTION MODIFICATION

Post transcription modification is needed in eukaryotes .

In this process the newly synthesized  pre-messenger RNA or RNA transcript having unusual length is converted into mature RNA .

It involves 

A- Cleavage 

The longer pre mRNA is cleaved to produce RNA of desired length .

B- Motivation 

The primary mRNA gives rise to mature RNA with extensive regulation of transcription 

C- Splicing 

In eukaryotic DNA both exon and sequence present so there may be unnecessary part new RNA .That part cut and exon parts are joined by ligase .

D- Capping 

Capping is dont in 5' with methyl group .

E- Tailing 

This involved addition of 250 adenine residues with a long chain of adenine. 

HGP AND ITS APPLICATION

Human Genome Project started in 1990 by US department of energy and national institute  of health and completed in 2003 .

It was associated biolnformatics .

A genome constitute haploid set of chromosomes in a cell 

Example - Human genome is packed in 23 pairs of chromosomes .

The main objectives of HGP was to develop gene mapping technique to identify gene having error to store information in database and develop DNA analysis tools and techniques to develop industrial  technology .

A human genome contains 3164.7 millions bases bases .

The average gene consists of 300 bases . The largest known gene in human dystrophin with 2,4 million bases.

The total number of gene is estimated to be 30000 and 99.9 bases are exactly same in all people .

Less that 2 percent genome codes for protein and human genome contain larger repetitive sequence .The repetitive sequence dont take part in coding but have and impact KN chromosome structure dynamics and evolution .

Chromosome 1 contains most genes with  2968 number of genes where as chromosomes y contain fewest with 23 genes 

1.4 millions location are identifies in human genome where single base DNA sequence  present .It is known as single nucleotide poly morphins .

APPLICATION

It can be used in disease administration and identifying gene causing disorder .

Disease can be studied in molecular level with therapeutic procedure .

It can be used in analysi  of evolutionary relationship between human and its close relatives relations like primates mammals .

It is used to identify difference between two ethane groups.

TRANSLATION

Translation can be defined as transfer of genetic information from mRNA to polypeptide is known as translation .

Translation can also be defined as  synthesis of protein from mRNA .

Translation occurs in cytoplasm along with protein synthesis 

Mechanism

1- Activation Of Amino Acids 

There are 20 types of amino acids present in cytoplasm .These are in inactive form .

They get activated by using ATP in presence of specific activating enzymes called amino acyl synthetase .This results in formation of amino acyl adenylate enzyme complex .

2- Transfer Of Activated Amino Acid To tRNA 

The amino acyl adenylate enzyme complex gets associated  with unpaired CCA  end of specific tRNA molecule .

An ester bond is formed between -COOH group of amino acid and -OH group of tRNA .

It result in formation of amino acyl tRNA complex and AMP is released AA-AMP enzyme + tRNA ...... AA-tRNA + AMP+ENZYME .

These are twenty specific tRNA for 20 specific amino acids.

3- Initiation  Of Polypeptide Chain 

Protein synthesis in initiated by initiation factors .There are three initiation factors in prokaryotes like IF1,IF2 ,IF3  similarly in eukaryotes there are nine initiation factors like  elF1 ,elF2 etc .

Ribosomes are scattered in cytoplasm as separated units .That means both the sub units are detached from each other 

elF2 or elF3 gets attached to the smaller subunits of ribosome . Cap part of mRNA gets attched to the ribosome in presence of GTP .Then bath the subunits are assembled to form 80s ribosome in eukaryotes and 70s ribosome in prokaryotes .

The larger sub-unit of ribosome has 3 rites .

These are p-site -peptide site 

A site - aminoacyl site and E-site-Exit Site 

The first amino acid tRNA complex gets attached to the p site i.e. AUG known as initiation codon 

The first amino acid formed in the process of translation is fermylated methionine incase of prokaryotes where as methionine in eukaryotes .

4- Elongation 

Next amino acyl tRNA complex complex comes to the A site and gets attached to mRNA with help of anticodon . This association requires GTP and two elongation factors EF-TS and EF-Tu 

Peptide bond is formed between the force carboxyl group of the first amino acid and the free amino group of the second amino acid .This reaction is catalysed by an enzyme peptidyl transferase present in larger sub-unit.

The incoming amino acyl tRNA complex moves to exit site from p-site i.e. outside the ribosome .It is released in cytoplasm .

The incoming amino acyl tRNA complex attched to A site known as amino acyl tRNA and the tRNA attched to site are called peptidyl tRNA due to formation of peptide bonds 

Then second amino acyl tRNA complex moves from A site to p site giving away space for next amino acid . This process is known as translacation .Here ribosome moves along mRNA from 5' -3' direction .

The A site is vacated a new codon enters this site and translocation is repeated 

5- Termination

Elongation of  polypeptide stops when moving ribosome come across three terminator codons like UAA ,UGA ,UAG .

In prokaryotes UAA and UAG are recognised by the releasing factor RF1 while RF2 recognised UAA or UGA 

RF terminator codon ribosome complex blacks further chain elongation .Then polypeptide chains reduced into cytoplasm and ribosomes gets dissciated from mRNA .

TRANSCRIPTION

Transcription is the process in which genetic information is transferred from DNA to RNA .

It is the synthesis of m-RNA from DNA .

Transcription  occurs in cytoplasm and in membrane bound in case of prokaryotes and eukaryotes respectively .

Mechanism Of Transcription 

These process of transcription involves five steps 

1- Activation of ribonucleotide 

Ribonucleotides get converted to their activated from .

There are four ribonucleotide like adenosine  monophosphate , guanosine monophosphate  , cytosine monophosphate and Uridine monophosphate .

They get converted to their activated form such as adenosine triphosphate , guanosine triphosphate , cytidine triphosphate and uridine triphosphate through the process of phosphorylation .

2 - Binding to promoter and initiation 

In DNA there are three regions i.e. promoter region expression region and terminator region .

The strat signals on DNA are called promoters .

Promoter regions are at rich region .There are at last 10 bases of A and T before mRNA synthesis .

This region has a common sequence of TATAAT commonly known as TATA box .

RNA polymerase gets bind to this promoter .The start singal is recognised by sigma factor .The only mRNA synthesis initiates .

Sigma factor is required case of prokaryotes where as in eukaryotes ,transcription factors like TFI and TFII are required for recognition of start signals .

After the attachment of RNA polymerase a bubble like structure is formed due to unwinding of helix known as transcription bubble .

Here RNA -DNA hybrid formation initiates .

3- Complementary base pairing 

The activated ribonucleotide come and lie opposite to the complementary base of DNA strands.

Example -u opposite A and c opposite G

4- Elongation of RNA chain 

Temporary hydrogen bond forms between the complementary base pairs of DNA-RNA hybrid .

RNA polymerase forms phosphodiester bond between adjecent nucleotides and RNA sugar phosphate backbone is formed to form a RNA strand .

RNA polymerase copies the DNA sequence accurately .

Only one strand or sense strand .The other DNA strand is not copied and is identical to mRNA  is known as anti-sence strand .

Elongation takes place only in 5' - 3' direction .

It occurs at a speed of 30 nucleotides per second .

The first nucleotide incorporated is always .A or G .

The newly synthesized DNA over template DNA is called RNA - DNA hybrid .

5- Termination 

Transcription of mRNA synthesis is terminated when RNA polymerase reaches terminator region .

Terminator region is GC rich region in prokaryotes and AT rich region in eukaryotes .

Rho factor is responsible for termination .It detaches the RNA polymerase from RNA -DNA hybrid .It also separated newly transcribed RNA from DNA by breaking hydrogen bond .

This type of termination is known as Rho dependent termination .

In Rho independent termination RNA transcription stops when newly synthesized RNA forms GC rich hairpin loop with a long sequence of uracil.

MECHANISM OF DNA REPLICATION

Different stages are involved in DNA replication . Those are 

1- Initiation of replication

Replication of DNA in E-coli always begins at a definite site called replication origin .

Prokaryotes like bacteria and viruses have only one replication origin .

In e-coil replication is due to multienzyme complex known as replisome .

Eukaryotes have more than one replication origin .These are arranged in a linear manner called replisome.

2- Formation of primary strand 

A new strand is synthesized opposite the parallel strand act as templates strand.

Primase initiates the production of short primary strand of RNA the primary formed towards the 3' end present strand .

In this process some other enzymes are involved . These are collectively known as primasomes .

The the primer strands elongates.

Once the initiation of DNA synthesis is completed . The RNA primer is removed by enzyme DNA polymerase .

2 - Elongation of new strand 

After the formation of primer strand , DNA replication occurs in 5'- 3' direction .That means deoxy ribonucleotides are added to 3' OH of nee strand with help of enzyme DNA polymerase 3 .

As the DNA replication occurs synthesis of a daughter strand occurs continuously on the upper strand .It is known as leading strand .

In another daughter strand short pieces DNA is synthesized .These fragments are known as O'kazaki  fragments .

This strand is discontinue as and known as lagging strand .

Dis contineous pieces of laggind strands are later joined by enzyme ligase to form contineous daughter strand .

The okazaki fragments are 1000- 2000 nucleotides long .

3- proof reading  and DNA repair

Some times a wrong base is introduced during replication . Its frequency is one in ten thousand .

This error is corrected by DNA polymerase enzyme with its error correcting activity known as proof reading .

It recognises the error removed the wrong nucleotide and allows the addition of proper base and then moves forward . 

REPLICATION OF DNA

The process by which DNA synthesized its own copy which structurally and functionally similar to the original one .

The process by which DNA synthesized its identical copy .

In eukaryotes replication of DNA is semi conservation in nature .

Semi-conservation made of replication means in a daughter DNA one strand comes from parent and one is newly synthesized .

Semi-conservation model of replication was suggested by Watson  and Crick .

Experimental evidance for semi-conservative replication was provided by Meselson and Stahl.

SHORT NOTE ON RNA

 RNA stands for Ribose Nucleic Acid .

RNA is present in all the living cells .

It is present in cytoplasm and nucleus .

It directs protein synthesis .

It is genetic material in few viruses .

Example - TMV 

Based on sorving as genetic material .RNA is of two types 

A- Genetic RNA 

     In viruses bacterial phages RNA is genetic material instead of DNA .

Example - TMV pea viruses

B- Non-genetic RNA

    There are organisms .Where DNA acts as genetic material .

On that case RNA is non-genetic .It is synthesized on DNA template .

Non- genetic RNA is of three types 

a- Messenger RNA  or m-RNA 

b- Transfer RNA or  t-RNA 

c- Ribosomal RNA or r- RNA