Structure of DNA

STRUCTURE OF DNA : DNA is the genetic material present in all the liiving organism and this ppt describe about the structure of DNA

1. STRUCTURE OF DNA BY – Uttaran Modhukalya Bahona College Zoology Department

2. ACKNOWLEDGEMENT We are very much pleased to submit our seminar topic on Structure of DNA for B.Sc. 2 nd semester. We sincerely thanks to our honorable principal Dr. Prasanna Kr. Dutta to give us opportunity for preparing the seminar topic and our Professors Dr.Indira Baruah (HOD), Dr.Gayatri Agni Bora and Dr.Bikramaditya Bakalial of Zoology department of our college for guiding properly the same. We are also thankful to our other respected teachers of the department and our friends and parents for supporting us and help to make the seminar on the above topic.

3. CONTENTS Introduction Discovery of DNA Chemical composition of DNA Phosphoric Acid Pentose Sugar Nitrogenous Base Structure of DNA formed by three main components Position of DNA in the chromosome Arrangement of DNA duplex Double helical structure of DNA Conclusion Reference

4. INTRODUCTION DNA is the genetic materials of all organisms which is present in chromosome bind with histone protein. DNA has two polynucleotide chain which form a helical structure. The main chemical components of the DNA are phosphoric acid, deoxyribose sugar and four different types of nitrogenous bases. The phosphoric acid bind with the sugar by ester bond, sugar-base bond is glycosidic bond and bases are bound by hydrogen bond. These are the basic component that form the complete DNA structure.

5. F. Miesher separate DNA from nucleus in 1869.In 1889 Altmann gives the term nucleic acid. Watson and Crick proposed the acceptable DNA double helix model that can explain the specificity and replicablity of the gene. DISCOVERY OF DNA-

6. The deoxyribonucleic acid mainly composed of three components- 1.Phosphoric acid(H 3 PO 4 ) 2.Pentose sugar and 3.Nitrogenous base . CHEMICAL COMPOSITION OF DNA-

7. It may occur also phosphate and forms the backbone of DNA molecule along with sugar molecule. It links the nucleotide by joining the deoxyribose sugar of two adjacent nucleotide with an ester phosphate bond. This bond connect 3prime carbon in one nucleotide with 5prime carbon in next. PHOSPHORIC ACID(H 3 PO 4 ):

8. Deoxyribose sugar is the pentose sugar bearing C 5 H 10 O 4 chemical formula .The structure of pentose sugar is pentagonal ring where 3 prime and 5 prime carbon atom attached to phosphoric acid and in 1 prime carbon atom to the base . PENTOSE SUGAR-

9. It is of two types - 1.Purine 2.Pyrimidine 1.Purine :- It compose of Adenine and Guanine with two heterocyclic ring and contain C,H,O and N atoms . NITROGENOUS BASE -

10. 2.Pyrimidine :–Mainly cytosine and thymine are the base present in DNA with single heterocyclic ring . NITROGENOUS BASE -

11. STRUCTURE OF DNA FORMED BY THESE THREE MAIN COMPONENTS: In case of DNA the ribose sugar’s 1prime C join to the base through glycosidic bond and this compound is known as nucleoside .When the 5prime C is joined with phosphoric acid by ester bond then the whole compound is known as nucleotide. The deoxyribonucleotide joined by phosphodiester bond and form a strand .Since DNA is double helix so, It has two strand .The another strand run in opposite or antiparallel direction i.e. if one strand is 3 prime to 5prime end forward direction then the another one is 5 prime to 3 prime end in backward direction. The two strand is joined by hydrogen bond between two nitrogenous base. The adenine always forms two numbers of bond with thymine and cytosine forms three bond with guanine base.

12. STRUCTURE OF DNA FORMED BY THESE THREE MAIN COMPONENTS: NUCLEOSIDE NUCLEOTIDE

13. Double helix structure of DNA:

14. POSITION OF DNA IN THE CHROMOSOME -

15. The diameter of DNA is 20Ǻ. Distance of major groove is 22Ǻ and minor groove is 12Ǻ. The distance of two base pair is 3.4Ǻ. The diameter of pyrimidine base is 3.3Ǻ and purine is 4.7Ǻ. ARRANGEMENT OF DNA DUPLEX:

16. From the above discussion we can concluded that DNA has the double helix that having two polynucleotide chain coiled with each other .We discuss about B-form DNA in the above topic . CONCLUSION

17. Textbook of medical biochemistry A K Berry Trueman elementary biology Internet REFERENCE

18. THANK YOU