IMPORTANCE OF WIND

Its direct effects are physical or mechanical while indirect effects are physiological .

Wind modifies the humidity .

Dry winds diffuse dwarfing of plants .

Wind helps in pollination , dispersal of fruits and seeds and prevents frost damage .

Sometimes shrubs and trees are planted to protect the field against wind .

Such structures are known as wind breaks or shelter belt .

These plants are planted at 90degree to the wind velocity.

It affects both plants and animals in the following ways

1- Strong winds cause soil erosion so reducing soil fertility .

These also cause desertification by shifting of sand particles to fertile areas .

2- These cause lodging of plants like wheat , rice , maize , oat , sugarcane , etc .

3- These increase the rates of evaporation and transpiration leading to desiccation which cause dwarfism in the plants . 

OPIATE NARCOTICS or OPOIOIDS

These drugs act as depressant and analgesic .

Thus they are commonly called pain killers.

They act on central nervous system and gastrointestinal tract e.g. Opium .

Opium is obtained from the dried latex of unripe capsules of white poppy plant , papaver somniferum .

The opium derivatives include morphine  and codein , heroin , commonly called black or brown sugar .

Heroin is formed from morphine by acetylation 

It is more powerful analgesic than morphine , but causes drug addiction .

Most dangerous opiate is heroin and is either smoked or inhaled or injected .

When heroin is injected intra venously it produces rapid response called rush .

The codein is a wild analgesic but causes syrup .

Asynthetic drug pethidine has similar effect to hose of opiates. 

TOBACCO ADDICTION

Tobacco is obtained from dried and cured leaves of tobacco plant , Nicotiana tobaccum .

The particulate constituent of tobacco is tar , aromatic hydrocarbon , phenol , cresol , benzaopyrene ,          N-nitrosonor nicotine and nicotine .

The gaseous constituent of tobacco is CO ,Nitrosomine  , hydrazine , formaldehyde , nitrogen oxide .

Smoking of tobacco causes lung cancer , cardio vascular diseases , pulmonary tuberculosis , bronchitis , gastric and duodenal ulcer. 

AUTOIMMUNO DISEASE

 Autoimmunity is a type of disorder when the immune system of an individual starts rejecting its own body cells or self .

This leads to variety of diseases called autoimmune diseases .

Example of autoimmune diseases are insulin -dependent diabetes , multiple sclerosis , rheumatoid arthritis, etc .

Multiple sclerosis is called by antibodies that attack the myelin sheath of new cells .

Some other autoimmune diseases are Hashimoto disease Grave's disease , Autoimmune haemolytic disease , etc 

IMMUNO- DEFICIENCY DISEASES

Immuno-deficiency diseases result due to defect in one or more components of the innate or adaptive immunity . 

Affected individuals are suspectible to diseases which normally would not bother most people .  

Severe combined immuno-deficiency results du to one of many genetic defects . 

One of such genetic defects leads to adenosine deaminase deficiency  .

SCID is characterised  by a very low number of circulatory lymphocytes . 

The affected individuals usually die at an early age .

AIDS is an example of immuno-deficiency caused by the infection from a retrovirus known as Human immuno-deficiency virus .

 Retroviruses have RNA genomes that replicate via DNA intermediate .

HIV selectively infects and kill T-halper cells . The depletion in T-helper cells weakens the acquired immuno response and may abolish it completely .

The viral RNA genome is converted to DNA copy by the action of viral enzyme reverse transcriptase .

The DNA copy of  HIV becomes inserted into the human chromosome and replicates with the cellular DNA  .

It may also be transcribed to produce RNA copies of viral genome .

The RNA copies are packed and liberated as viral particle .

The infected cell is lysed in this process and the released virus particles infect new T-helper cells .

HYPERSENSITIVITY OR ALLERGY

An allergy is the hypersensitivity of immune system of a person to some foreign substance called allergy which either comes in contact with or enters the body .

The allergies  include dust , moulds ,  pollen , certain foods and madicines such as penicillin .

Allergy involves mainly  IgE antibodies and histamine .

The common manifestation of allergy is asthma and sometimes an allergy may caused a sudden , violent fatal reaction in a sensitive individual , it is called anaphylaxis.

METHODOLOGIES

 The  HGP  researchers collected blood (female) or sperms (male) samples from large number of doners .

They used  white blood calls from blood of male and female doners .

For sequencing, the total DNA from call is isolated and converted into random fragments of smaller sizes approximately 150,000 base pairs in length .

These pieces then ligated to a type of vector known as bacterial artificial chromosome (BACs) the BACs are derived from bacterial chromosome which have been generally engineered .

The vector containing the pieces of  DNA  was inserted into bacteria (host).

In bacteria the pieces of DNA are copied by bacterial DNA replication. .

In this process several copies of DNA pieces were made, each piece of DNA fragment can be sequenced using automated DNA sequence developed by f. sanger who determined aminoacid  sequence of proteins.

 Another vector YAC (yeast artificial chromosome)  was also used for  above purpose. 

Sometime these sequences have some overlapping regions which can only be sequences with help of computer based programme .

The process of identifying all genes with their coding and non-coding sequence with function called sequence annotation and is the domain of bio-infomatics .

The methods involved for identifying all genes that expressed as RNA called expressed sequence  tags (ESTs). 

STEPS OF TRANSCRIPTION

1-  Initiation of transcription

RNA polymerase enzyme binds promoter region of DNA . The specific site for the enzyme binding is called TATA BOX .

The double stranded DNA unwinds .

The sigma factor initiate the process .

The first nucleotide binds to the enzyme complex .

The sigma factor is released from core enzyme 

2- Elongation of RNA chain 

The elongation is the function of RNA polymerase core enzyme .

The enzymes moves on DNA template .

Nucleotides added at OH-- end of nucleotide to form a new RNA strand , and one pyrophosphate is released for each nucleotide added .

The average speed of transcription is 40 nucleotides per second.

The RNA chain grows in the 5' - 3' direction .

3 - RNA chain termination

Two mechanisms are well known . They are

I- Intrinsic termination 

It is also called Rho independent termination .

The RNA polymerase recognise a palindrome sequence  of on DNA that from a hair pin loop on the RNA chain .

Therefore , it dissociates from the DNA.  

II- Rho dependent termination 

This uses a protein called p.

The Rho protein stops RNA synthesis at specific sites .

FEATURES OF HGP

Genome is the total hereditory information of an organism . It  includes gene and non-coding sequences of DNA .

The human genome  has approximately 3.3billion base pairs and there are approximately 23000 genes in human being .

The average gene consists of 3000 bases .

Human genome has significantly more repeated sequences than other mammalian  genome They are thought to provide idea on chromosome structure , dynamics and evolution .

The function are unknown over 50 percent of discovered genes .

Less than 2  percent genome codes for protein .

The chromosome 1 has most genes and y-chromosome has the fewest genes .

It is known that there are about 1.4million location where single base differences occure in humans .   This called single nucleotide polymorphism .

DNA PACKAGING

 The distance between two consecutive base pair is 0. 34 nm or 0.34 into 10 to the power -9 m . The total number of base pair in a mammalian cell is about 6.6 into 10 to the power 9 bp . There fore the length of the DNA is calculated , that is 6.6 into 10 to the power 9 bp into 0.34 into 10 to the power -9 m , it comes to be approximately 2.2 meters.

In prokaryotic cells DNA remains in nucleoid of the cells . As DNA is negatively charged , it is surrounded by some positively charged proteins .

In eukaryotic cells DNA lies inside the nucleus . Hence nucleus is called the cage of DNA . The DNA remains in association with positive charged proteins called Histones .Histones are rich in basic aminoacid residues lysines and arginines .

Histones are organised to form a unit of eight molecules called a histone octamer .

The negatively charged DNA  is wrapped around the positively charged histone octomer to form a structure  called nucleosome.

A typical nucleosome contains about  200bp of  DNA helix .

Nucleosomes constitute the repeating unit of a structure in the nucleus called chromatin .

The packaging of chromatin at higher level requires additional set of proteins that collectively referred as Non-histone  chromosomal proteins .