The document discusses nucleic acids, focusing on their structure, composition, and functions in genetics and biotechnology. It covers the components of nucleotides, the transformation principle established by Griffith, and the structural models of DNA proposed by Watson and Crick. Additionally, it differentiates between DNA and RNA and describes various forms of DNA, highlighting their characteristics.

1. Nucleic acid
Introductory Genetics and Biotechnology
(Biotech-401), 3(2-1)
Lecture No. 17-18

2. F. Miescher
Journey from nuclein to nucleic acid

3. A. Kossel
Nucleic acid contains nitrogenous bases

4. Nitrogenous bases
Purine
(Basic structure)
Pyrimidine
(Basic structure)
Adenine Guanine Cytosine Thymine Uracil

5. The nucleotides
Composition of Nucleotide
T. Levene
It is composed of a nitrogen base, a five-
carbon sugar, and one or more phosphate
groups

6. Four types of nucleotides
A G C T A G C T
Tetra-nucleotide theory

7. Cgargaff rules Table
A T G C T T C A

8. Composition of Nucleoside
A nucleoside consists simply of a nitrogen base (also
termed a nitrogenous base) and a five-carbon sugar
(either ribose or deoxyribose),

9. What is the function of a nucleotide
Involved in the synthesis
of DNA
Nucleotide

10. Involved in the synthesis of RNA

11. DNA is a hereditary material
Fred Griffith experiment (1928)
Type IIIS
(Virulent)
Type IIR
(Nonvirulent)
H-K
type IIIS
A mixture of RII
and
H-K type IIIS
Conclusion:
Transformation principle
transformed the type IIR
bacteria into live, virulent type
IIIS bacteria.

12. • After 10 years of
experimentations
• Purified the transforming
substance
Heat killed
Avery, MacLeod & McCarty IIIS (Virulent)
Filtrate of IIIS
Type IIR
Type IIIS
and IIR
bacteria
Type IIIS
and IIR
bacteria
IIR bacteria
RNase
Protease
DNase

13. Structure of DNA

14. Wilkins & Franklin
Use of X-rays

15. Watson and crick
model of DNA

16. Minor
groove
Major
groove

17. Watson and crick
model of DNA

18. Difference in RNA and DNA

19. Sugar molecule

20. Nitrogenous bases

21. RNA and DNA strands

22. Characters DNA RNA
Lifetime Long Short
Formation process Replication Transcription
Types Nuclear DNA and
mtDNA
mRNA, rRNA,
tRNA etc.
Length Long Short
Genetic material In all organisms Only in viruses

23. Different forms of DNA
B form
• Plenty of water and no unusual base sequence
• Predominant form in cell
• Alpha helix (right handed)
A form
• Exist under less water environment
• Alpha helix (right handed)
• Shorter and wider
Z form
• Left handed
• Sugar-phosphate backbone bone zigzag back and forth
• Long stretches of alternating C and G nucleotides

24. B-Form A-Form Z-Form
Helix sense Right Handed Right Handed Left Handed
Base pairs per turn 10 11 12
Vertical rise per bp 3.4 Å 2.56 Å 19 Å
Rotation per bp +36° +33° -30°
Helical diameter 20 Å 20 Å 20 Å

25. Thanks

26. Sugar in nucleic acid
Phosphate in DNA

27. DNA
RNA

28. Deoxyuracil 5’-
monophosphate
(dUMP)
Uracil

29. Diameter 20 Å
One Complete
turn 34 Å
Minor groove
Major groove
Sugar-phosphate
backbone
Nitrogenous base
pair
3.4 Å
Major
groove
Minor
groove