DNA REPLICATION PDF
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DNA MODEL OF SHASHISEKHRAN
शशिशेखरन का डीएनए मॉडल 👈 पीडीएफ देखने और डाउनलोड करने के लिए यहां क्लिक करें। पर मेरी वेबसाइट क्लिक पालन करने के लिए "दृश्य वेब संस्करण" 👇
Chargaff's rules
Chargaff's rules:- One other key piece of information related to the structure of DNA came from Austrian biochemist Erwin Chargaff. Chargaff analysed the DNA of different species, determining its composition of A, T, C, and G bases. He made several key observations: A, T, C, and G were not found in equal quantities (as some models at the time would have predicted) The amounts of the bases varied among species, but not between individuals of the same species The amount of A always equalled the amount of T, and the amount of C always equalled the amount of G (A = T and G = C) - Purines always equal to pyrimidine . ( A+G = T+C ) - MOLAR RATIO BETWEEN PURINE AND PYRIMIDINE IS ALWAYS 1 (1:1) - BASE RATIO IN DNA ( A+T/G+C ) IS ALWAYS FIXED IN A SPECIES BUT DIFFERENT IN DIFFERENT SPECIES . In Prokaryotes = < 1 ( less than 1 ) In Eukaryotes = > 1 ( more than 1 ) These findings, called Chargaff's rules, turned out to be crucial to Watson and Crick's
WATSON AND CRICK MODEL OF DNA
Watson and Crick Model of DNA- - Two British scientist James D. Watson and F.H.C. Crick(1953) presented a universally accepted model of DNA . That time they were working in Cambridge University. According to them the DNA molecule have high molecular weight and double strands . - That time Watson and Crick also had results of X-ray Diffraction collected by Maurice Wilkins, Rosalind Franklin and his colleagues. Following are the main points of this model- 1. Each DNA molecule is made up of two polydeoxyribonucleotide strands. 2. Each polynucleotide strand is made up of many nucleotides joined together by phosphodiester bonds. 3. All N-base in nucleotides are attached to the first carbon of deoxyribose sugar. 4. Thymine is located in second strand just in front of the Adenine located in first strand, similarly Cytosin is located in front of Guanine. These strand are called Complementary Strands. 5. The Adenine base locate in the first strand of DNA molecule forms two H
ASSEMBLY OF DIFFERENT COMPOUNDS IN DNA PDF
ASSEMBLY OF DIFFERENT COMPOUNDS IN DNA 👈 click on this link to open pdf
ASSEMBLY OF DIFFERENT COMPOUNDS IN DNA
Assembly of different compounds in DNA:- Generally following three terms are used to clearly understand the combination of different chemical components in DNA- 1. Nucleoside 2. Nucleotide 3. Polynucleotide 1. Nucleoside- A molecule made from combination of Nitrogen base and Pentose sugar is called Nucleoside. Types of Nucleotides- A. Deoxyadenosine B. Deoxyguanosine C. Deoxythymidine D. Deoxycytidine 2. Nucleotide:- A molecule made from the combination of a Nucleoside and phosphoric acid is called Nucleotide. Nucleoside (Deoxyribose sugar + nitrogen base) + Phosphoric acid =Deoxyribonucleotide Types of Nucleotide- A. Deoxyadenylic acid B. Dexyoguanylic acid C. Deoxycytidylic acid D. Deoxythymidylic acid 3. Polynucleotide- Many Nucleotide monomers combine to form a polynucleotide chain by phosphodiester bonds.
CHEMICAL ORGANISATION OF DNA PDF
CHEMICAL ORGANISATION OF DNA 👈 click on this link to view and download PDF
Chemical Organization Of DNA
Chemical organisation of DNA: - According to chemical analysis DNA is produced by following three types of compounds- 1. Pentose Sugar 2. Phosphate 3. Nitrogenous base 1.Pentose Sugar:- (A) It is 5 member ring. (B) 4 Carbon and 1 oxygen atoms form ring, the 5th carbon atom is attached with the group –CH2 on outside of the ring. (C) Deoxyribose sugar has one oxygen atom absent at carbon No.2 compared to ribose sugar. 2.Phosphate:- The phosphate group in DNA is present as phosphoric acid. 3. Nitrogenous base: - On the chemical basis there is two types of nitrogen bases- (a) Pyrimidine (b) Purines (a) Pyrimidine :- - These are nitrogen compounds of single ring. - Its 6 member benzene ring have Nitrogen atom at the site number 1 and 3. - A DNA molecule have two types of pyrimidines- 1. Cytosine (2-Hydroxy-6-amino pyrimidine) 2. Thymine (2,6 Dihydroxy-5-methyle pyrimidine) * In RNA uracil is found in place of thymine. (b) Purines:- - These are Nitrogen compounds of 2 rings. -
DNA TYPES
Types of DNA:- Following are the 7 main types of DNA- 1. The B-Form of DNA (B- DNA): Structure of B-form of DNA has been proposed by Watson and Crick. It is present in every cell at a very high relative humidity (92%) and low concentration of ions. It has antiparallel double helix, rotating clockwise (right hand) and made up of sugar- phosphate back bone combined with base pairs or purine- pyrimidine. The base pairs are perpendicular to longitudinal axis of the helix. The base pairs tilt to helix by 6.3°. The B-form of DNA is metabolically stable. The length of a complete turn is 34 Angstroms and number of bases pairs in a complete turn is 10 (10.4). The diameter of helix is 20 Angstroms and height of each base pair is 3.38 Angstroms. Each base pair accounts for 36(34.6 angstrom according to 10.4 base pair per helix turn, 360/10.4 =34.6) degree of rotation, creating a minor groove and a major groove. 2. The A-Form of DNA (A- DNA): This DNA have clockwise (right
DNA
INTRODUCTION :- Full form – Deoxyribonucleic Acid First time Frederic Miescher discovered DNA in pus cells in 1869 and called it nuclein. Because of Nuclein’s acidic nature in 1899 Richard Altman called it Nucleic Acid. History of Nucleic Acid 1. Freidrich Miescher (1869) He discovered DNA in pus cells and called Nuclein. 2. Richard Altman (1899 ) He called nuclein as Nucleic Acid. 3. O.F. Griffith (1928) He discovered Transformatin in bacteria. 4. J.D. Watson and F.H.C. Crick (1953) Described Double Helix Model of DNA. 5. Kuhn (1957 ) Calculated molecular weight of DNA. 6. H.F. Conart (1957 D) RNA in T.M.V. as genetic material 7. Meselson and Stahl 1958 Described Semiconservative method of DNA replication. DNA Nature:- Most organisms, plants, bacteria, animal virus, bacteriophage and plant virus have double strand DNA but some bacterial virus such as phi*174 and S13 have single strand DNA. Shape:- The DNA in eukaryotic cells is threadlike and straight whereas in p