DNA INFORMATION IN DETAIL

Watson and crick in 1950 determined the structure of DNA using X Ray crystallography in 1953 describe the structure of DNA
The important feature of watson crick model or double helix model of DNA are as follows
1· The DNA molecule consists of two polynucleotide chains or stands spirally twisted around each other and cold around a common Axis to form a right handed double helix.
2· The two strands are antiparallel they run in opposite directions so that the third end of one chain facing v end of the other.
3·The sugar phosphate backbone remain on the outside while the core of helix contain the purine and pyrimidine bases.
4·The two strands are held Together by hydrogen bond between the purine and pyrimidine base of the opposite stands.
5·The diameter of DNA is 2.0nm or 20 Å.
6·Adjacent bases are seperated 0.34nm or by 3.4Å along axis.
7·The length of complete turn of helix is 34Å .
8· There are 10 BP per turns
9· Adenine(A) always pair with thymine(T) by  to hydrogen bond & guanine(G) always pair with cytosins(c) by three hydrogen bond. This complimentary is know as the base pairing rule.
10· They are two types of groove in DNA- major groove and minor groove.

Function of DNA

1:-DNA is a genetic material which carries all the the hereditary information the genetic information is coded in the sequence of nitrogenous base.
2:-DNA has a unique property of replication production of carbon copies this is essential for transfer of genetic information from one cell to its daughter and from one generation to Next generation
3:-DNA occur inside chromosomes during meiosis crossing over gives rise to the new combination of gene called recombination
4:- change in the sequence of nitrogenous base due to the addition,deletion /wrong. Replication is called Mertation, which the fountain head of variations and evolution.
5:-DNA form RNA true process of replication.
6:- It controls metabolic reaction of the cell through synthesis of enzyme.
7:- Due to the  differential function of specific region of DNA cell are differentiated to perform specific function.
Forms of DNA.

There are various forms of DNA

A-form of DNA 
The a form of DNA is found at 75% relative humidity in a presence of NA+,K+ & Cs+ ions. it contain 11 base pair as compared to the 10 base pair of B DNA which tilt form the  axis of helix by 20 degree.
B form of DNA
 The structure of B form of DNA has been produced bi patsan and Crick it is present in every cell at a very high relative humidity 92% and low concentration of ions it is antiparallel double helix rotating clockwise (right hand) & made up of sugar phosphate backbone combined with base pair of purine pyrimidine.
C form of DNA
 C form of DNA is found at 66% relative humidity in the presence of Lithium ion as compared to A and B DNA in C DNA the numbers of base pair per turn is less.
D form of DNA 
The D-form of DNA is found rarely as extreme variants total number of base pairs per turn of helix is 8 therefore it shows 8 fold symmetry this form is also called Poly (DA-DT) & poly (DA-DC) form.
 Z form of DNA
 In 1979 rich and co-workers at MIT in USA obtained Z DNA by artificially synthesizing d(C-G) 3 molecules in the form of crystals they proposed a left handed double helix model with zigzag sugar phosphate backbone running in antiparallel direction

PROTEIN

The substance that's found in food like egg, meals. which help people for growth and  healthy is called protein.

Classification of protein

On the basis of constitution protein are three types.
1. Simple protein.
2. Conjugate protein.
3. Derived protein
·Simple protein:- Simple protein are built of one or more complete polypeptides without any additional group. They are composed solely of amino acid. They are further divided into two categories.
A. Structural protein.:- They are constituents of active protoplasm. Depending upon their function. The structural protein or 'enzymatic' & non-enzymatic.

B. Reserve or storage protein:- These protein are present as food reserve. They are globular and soluble in water. Some of them are heat sensitive also.

· Conjugated protein:- These protein contains in addition to amino acids other organic and inorganic material called prosthetic group of proteins.

Eg- HAEMOGLOBIN:- It contain iron as additional component.
GLYCOPROTEIN:- It contain carbohydrates as additional component.
LIPOPROTEIN:- It contain lipids as additional component.

· Derived protein:- They include met proteins, albuminoses, peptones, polypeptides and other products of partial hydrolysis of protein. They are intermediate products which do not accumulate.

Classification of protein.

On the basis of shape.
Fibrous protein:- They are thread-like proteins which may occur single in group s to form sheets. When they occur in groups, the polypeptide chains run parallel along a single axis. F·P are tough & insoluble in aquatic solution. They are non-enzymatic but structural proteins.

fibrous protein

Globular protein:-They are proteins in which the tightly packed polypeptide chains are coiled and abundantly folded to form sphere or globes. They may be enzymatic or non-enzymatic. They are generally soluble in aqueous solution and are capable of rapid fusion.

Function of protein.

1. They are the major constituents of protoplasm.
2. They are essential for cell division, growth,repair and reproduction.
3. Connective tissue of animals is two types of protein fibres- collagen & elastin.
4. Nucleoproteins performs an important function in controlling the working of DNA.
5. Some protein take part in the transport of substance. Example:- oxygen by haemoglobin.
6. Reserve protein provide amino acid for growth and repair eg. Albumin.
7. Some protein function as antibodies.
8. They act as buffers, since they resist the change in PH of the cells.
9. Toxin protein are used as defense by organisms eg snake venom.
10. Some protein act as hormones & regulate various activities in living organism eg Growth hormones.

Various levels of structure of protein

primary structure:-It consists of the sequence of amino acid residues joint through peptide bonds in the polypeptide of a protein the number of amino acid residues in a chain and the arrangement of amino acid are usually specific as each polypeptide is synthesized under construction from a cistron of DNA through mRNA.
Secondary structure:- It refers to the manner of extension or helical coiling of the polypeptide chain (particularly in fibrous protein). Which results mainly from hydrogen bonding between oxygen of carboxylic group of one amino acid residues and 'NH' group of next 4th amino acid residue. It is various types but  two main categories
1. Alpha helix
2. Beta-pleated sheet

Alpha helix:- Alpha helix is a secondary structure of proteins that consists of a peptide chain folded into right-handed spiral conformation & stabilized by H-bonds between C=O of one amino acid & N-H of fourth amino acid from that postion.

Beta-pleated sheet:- Beta-pleated sheet are made of Beta strands connected laterally by 2 more hydrogen bond forming a backbone twisted, pleated sheet. this structure occur when two or more segments of polypeptide chain overlap one another & and form hydrogen bond with each other.
Tertiary structure:- It refers to the folding and bending of polypeptide chain to form globular protein include buy covalent disulphide bonds (-S-S),hydrogen & Salt bonds & hydrophobic/hydrophilic interaction.
Quarternary structure:- It is found only those proteins which have two or more polypeptides. it refers to the manner in which the individual polypeptide chains fit together in a multimeric or oligomeric protein example:- in haemoglobin.

Prokaryotic cell

Prokaryotic cell:- Prokaryotic cell is that cell which lacks a well-defined nucleus and membrane-bound organelles.

For example: Bacteria,cyanobacteria,PPLO [Pleuro-pheumonia like organism]

Prokaryotic cell diagram

1. Cell wall: cell wall in bacteria is made up of peptido-glycan which is a polymer of NAG & NAM.
NAG:- N-acetylglucosamine  : NAM:- N-acethylmuramic acid
· It provide shape and rigidity to cell
2. Glycocalyx:- It is made up of polysccaride orprotein or both.
Function-  It helps in the attachment of bacterial cell of various surfaces. In some bacteria,it also contribute to pathogenicity.[ Disease causing ability]
3. Flagella:- It is present in some bacteria. It is a locomotory structure that helps in the movement of bacteria. It is made up of protein called flagellin. Flagella is single standed in bacteria.

4. Plasma membrane: Plasma membrane is selectively permeable membrane present around cell
5. Mesosome: The are invagination or infolding of plasma membrane.

It has a role in DNA replication
It has a role in the formation cell septum for cell division. 
Also help in repiration, secretion process and to increase the surface area of plasma membrane
6. Nucleoid: The naked DNA of prokaryotes which is not enclosed inside the nucleus is called nucleoid/ Genophore. In addition to genomic DNA, many bacteria have small circular DNA outside genomic DNA plasmids, which confers traits like antibiotic-resistance to bacteria.
7. Ribosomes: They are the protein factory of the cell. In prokaryotes ribosome lie freely in the cytoplasm and are of 70`S type, which have two subunits 50S & 30S.There are two types of ribosomes 
1.70S ribosomes
2. 80S ribosomes
8. Thylakoid: They are present in some bacteria & blue-green algae which are autotrophic.They lie in cytoplasm and contain pigmets such as bacteria chlorophyll.
9. Protein granules & lipid globules: They lie freely in the cytoplasm.
10. Gas vacuoles: they are not true vacuoles & are present in some bacteria to provide buoyancy. 
Example:- These gas are present in purple & green photosynthetic bacteria.

Genitcs of blood group

1. The ÁBÒ blood group system is controlled by three alleles Ia,Ib&i. Ia encodes for A antigen. Blood group shows multiple allelism.

2.Ib encodes for B antigen & 'i' does not encodes for any antigen.

3.Ia&Ib arw co-dominant& each is dominant over 'i'.

4. The antigen encoded are parent on surface of RBCs

5. Over 300 blood group specificities on red cells have been identified, many of which are polymorphic. The molecular mechanisms responsible for these polymorphisms are diverse, though many simply represent single nucleotide polymorphisms (SNPs). Other mechanisms include the following: gene deletion; single nucleotide deletion and sequence duplication, which introduce reading-frame shifts; nonsense mutation; intergenic recombination between closely linked genes, giving rise to hybrid genes and hybrid proteins; and a SNP in the promoter region of a blood group gene. Examples of these various genetic mechanisms are taken from the ABO, Rh, Kell, and Duffy blood group systems. Null phenotypes, in which no antigens of a blood group system are expressed, are not generally polymorphic, but provide good examples of the effect of inactivating mutations on blood group expression. As natural human ‘knock-outs’, null phenotypes provide useful clues to the functions of blood group antigens. Knowledge of the molecular backgrounds of blood group polymorphisms provides a means to predict blood group phenotypes from genomic DNA. This has two main applications in transfusion medicine: determination of foetal blood groups to assess whether the foetus is at risk from haemolytic disease and ascertainment of blood group phenotypes in multiply transfused, transfusion-dependent patients, where serological tests are precluded by the presence of donor red cells. Other applications are being developed for the future.
6.Rh Blood group system:-If the individual possess rhesus antigen, he is Rh+ & if rhesus antigen is absent, he is Rh-

Univesal donor:-That individual that does not have any antigen on its RBC. Ex O-

Universal acceptor:- That possess all the antigen on RBC.Ex AB+ ( A antigen, Bantigen,Rhesus antigen)