DNA structure and types

this slide contain material related to this topic with diagrams

1. DNA-Types &Structure Presented To: Presented By: S.O.S. in Microbiology Anurag Gupta Jiwaji University, Gwalior M.sc 1 St Semester 1

2. Content Introduction Components Structure of DNA Types of DNA Bibliography 2

3. Introduction Of DNA DNA is a double stranded molecule that is twisted into a Helix DNA are macromolecular structures composed of regular repeating Polymers formed from nucleotides. DNA is a complex molecule that contains all of the information necessary to build and maintain an organism 3

4. Components of a nucleotide Nitrogenous Bases Deoxyribose Sugar Phosphate Group 5

5. Nitrogenous bases 6 Basic structure

6. Pyrimidines 7

7. Purines 8

8. Sugar Deoxyribose sugar The sugars found in nucleic acids are pentose sugars; a pentose sugar has five carbon atoms. Deoxyribose, found in DNA, is a modified sugar, lacking one oxygen atom (hence the name "deoxy"). 9

9. Phosphate Group A phosphate group is just a phosphorus atom bound to four oxygen atoms, but it has many important roles. Along with sugars and bases, it makes up nucleic acids. 10

10. 11 Phosphate Sugar Base Nucleotide Nucleoside X=H: DNA X=OH: RNA

11. Nomenclature of Nucleic Acid Components Purines Pyrimidines 12 Base Nucleoside Nucleotide Adenine Deoxyadenosine Deoxyadenylate Guanine Deoxy guanosine Deoxyguanylate Base Nucleoside Nucleotide Cytosine Deoxycytidine Deoxycytidylate Thymine deoxythymidine deoxythymidylate

12. DNA Primary structure 13 3’ end 5’ end 5’ 3’ Phosphodiester linkage

13. The secondary structure of DNA Watson and Crick Model: The sides of the ladder are made up of alternating molecules of phosphate and deoxyribose. The bases make up the rungs of the ladder are attracted by a weak chemical bonds called hydrogen bonds. The DNA double helix is anti-parallel, which means that the 5' end of one strand is paired with the 3' end of its complementary strand (and vice versa). 5'--------------->3‘ 3'<---------------5' Two hydrogen bonds connect T to A; three hydrogen bonds connect G to C. 14

14. The secondary structure of DNA is the double helix 15

15. Types of DNA A DNA B DNA Z DNA 16

16. A-DNA A-DNA is one of the many possible double helical structures of DNA. It is most active along with other forms. Helix has right-handed sense, shorter more compact helical structure. It occurs only in dehydrated samples of DNA, such as those used in crystallographic experiments . 17

17. B- DNA Helical sense: right handed. Base pairs :almost perpendicular to the, helix axis; 3.4 Å apart. One turn of the helix: 36 Å; ~10.4 base pairs. Minor groove: 12 Å across. Major groove: 22 Å across. 18

18. Z-DNA Z-DNA is one of the many possible double helical structures of DNA. Helix has left-handed sense. It is most active double helical structure. Z-DNA was first discovered in 1979, certain proteins bind very strongly to Z-DNA. 19

19. Types of DNA Property A-DNA B-DNA Z-DNA Helix Handedness Right Right Left Base Pairs per turn 11 10.4 12 Rise per base pair along axis 0.23nm 0.34nm 0.38nm Pitch 2.46nm 3.4nm 4.56nm Diameter 2.55nm 2.37nm 1.84nm Major Groove Present Present Absent Minor Groove Present Present Deep Cleft 20

20. Function of DNA Scientists have since discovered that certain proteins bind very strongly to Z-DNA, suggesting that Z-DNA plays an important biological role in protection against viral disease. The main role of DNA in the cell is the long-term storage of information 21

21. Recent work The transformation of the DNA template in RNA polymerase II transcription : James T. Kadonaga on 22-08-2019 22

22. Bibliography Principals and techniques of biochemistry and molecular biology 7th edition-Wilson & walker(page no 139) Principle of Biochemistry –David .L . Nelson & Michael .M. Cox(Chapter 8.Nucleotides) https://www.nature.com/scitable/topicpage/introduction-what-is-dna-6579978/ 23

23. 24