2. DNA STRUCTURE DNA consists of two molecules that are arranged into a ladder-like structure called a Double Helix. A molecule of DNA is made up of millions of tiny subunits called Nucleotides.

3. DNA STRUCTURE Each nucleotide consists of: 1.Phosphate group 2.Pentose sugar 3.Nitrogenous base

4. NUCLEOTIDES Phosphate Pentose Sugar Nitrogenous Base

5. NITROGENOUS BASE

6. PENTOSE SUGAR D-

7. PHOSPHATE GROUP

8. D-RIBOSE 5-PHOSPHATE

10. NUCLEOTIDES

11. NUCLEOTIDES

13. NUCLEOSIDES IN DNA BaseSugarNucleoside Adenine (A)DeoxyriboseAdenosine Guanine (G)DeoxyriboseGuanosine Cytosine (C)DeoxyriboseCytidine Thymine (T)DeoxyriboseThymidine

14. NUCLEOSIDES IN RNA BaseSugarNucleoside Adenine (A) Ribose Adenosine Guanine (G) Ribose Guanosine Cytosine (C) Ribose Cytidine Uracil (U)RiboseUridine

15. NUCLEOTIDES IN DNA AND RNA DNA_ dAMPDeoxyadenosine monophosphate dGMPDeoxyguanosine monophosphate dCMPDeoxycytidine monophosphate dTMPDeoxythymidine monophosphate RNA AMPadenosine monophosphate GMPguanosine monophosphate CMPcytidine monophosphate UMPuridine monophosphate

16. HYDROGEN BOUNDS

18. DNA BACKBONE AND RUNGS The phosphate and sugar form the backbone of the DNA molecule, whereas the bases form the “rungs”.

19. DOUBLE HELIX OF DNA DNA contains two strands of nucleotides H bonds hold the two strands in a double-helix structure A helix structure is like a spiral stair case Bases are always paired as A–T and G-C Thus the bases along one strand complement the bases along the other

21. THE GENE IS SECTION OF DNA A gene is a section of DNA that codes for a protein (or RNA). Each unique gene has a unique sequence of bases. This unique sequence of bases will code for the production of a unique protein. It is these proteins and combination of proteins that give us a unique phenotype.

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