1. Nucleic Acids 1

2. WHAT ARE NUCLEIC ACIDS? Used for: Storing genetic information Assembly instructions for protein synthesis Energy molecule (ATP – adenosine triphosphate) Two major nucleic acid polymers: DNA: deoxyribonucleic acid RNA: ribonucleic acid

3. The distribution of nucleic acids in the eukaryotic cell  Two types of Nucleic Acid: DNA and RNA  DNA is found in the nucleus with small amounts in mitochondria and chloroplasts  RNA is found throughout the cell 3

4. NUCLEIC ACIDS DNARNA - Located in the nucleus- Located mostly in the cytoplasm - Double-stranded, double helix structure - Single-stranded structure - Stable molecule- Less stable molecule

5. NUCLEIC ACID STRUCTURE  Nucleic acids are polynucleotides  Many nucleotides  Their building blocks are nucleotides  Nucleotides: nitrogenous base + 5 carbon pentose (sugar) + phosphate 5

6. NUCLEOTIDES Monomer of nucleic acids Three components: 1.Phosphate 2.Pentose sugar 3.Nitrogenous base

7. Nucleotides Nucleic acids consist of nucleotides that have a sugar, nitrogen base, and phosphate nucleoside 7 Sugar Base PO 4 SUGAR Ribose or Deoxyribose BASE PURINESPYRIMIDINES Adenine (A) Guanine(G) Cytocine (C) Thymine (T) Uracil (U)

8. Nitrogen-Containing Bases 8 PurinesPyrimidines

9. NITROGENOUS BASES Purines Pyrimidines RNA DNA

10. PENTOSE SUGAR

11. Sugars 11

12. Nucleotides in DNA and RNA DNA dAMPDeoxyadenosine monophosphate dGMPDeoxyguanosine monophosphate dCMPDeoxycytidine monophosphate dTMPDeoxythymidine monophosphate RNA AMPadenosine monophosphate GMPguanosine monophosphate CMPcytidine monophosphate UMPuridine monophosphate 12

13. Nucleosides in DNA Nucleosides are the precursors to nucleotides; they are not phosphorylated BaseSugarNucleoside Adenine (A)DeoxyriboseAdenosine Guanine (G)DeoxyriboseGuanosine Cytosine (C)DeoxyriboseCytidine Thymine (T)DeoxyriboseThymidine **T is only found in DNA** 13

14. Nucleosides in RNA BaseSugarNucleoside Adenine (A)riboseAdenosine Guanine (G)riboseGuanosine Cytosine (C)riboseCytidine Uracil (U)riboseUridine **U is only found in RNA** 14

15. NUCLEOSIDE

16. Structure of Nucleic Acids  Polymers of four nucleotides  Linked by alternating sugar-phosphate bonds  RNA: ribose and A, G, C, U  DNA: deoxyribose and A,G,C,T nucleotide nucleotide nucleotide nucleotide 16 P sugar base P sugar base P sugar base P sugar base

17. Nucleic Acid Structure 17 3 5 3,5-phosphodiester bond

18. Nucleic Acid Structure  Covalent bond between the phosphate group of 1 nucleotide and the hydroxyl group on the carbon three of the sugar on the adjacent nucleotide

19. PHOSPHODIESTER BOND Phosphodiester bond formed between nucleotides: Pentose sugar (-OH group) Phosphate group

20. ‘BACKBONE’ OF DNA Linking nucleotides produces a single strand of DNA Phosphate + deoxyribose = backbone

21. COMPLIMENTARY BASE PAIRING Nitrogenous bases are joined through Hydrogen bonding Complimentary base pairs: Adenine + Thymine 2 H bonds Cytosine + Guanine 3 H bonds

22. ANTI-PARALLEL STRANDS Complimentary base pairing results in double-stranded DNA Both DNA strands run anti-parallel to each other (oriented in opposite directions) One strand is 5’  3’ while the other is 3’  5’

23. COMPLIMENTARY BASE PAIRING The 2 anti-parallel strands coil together to form a double helix.

24. Structure of Nucleic Acids  DNA contains two strands of nucleotides  Each strand of DNA has a free phosphate group at one end and a free sugar at the other end  DNA takes on a helix structure, like a spiral stair case  Bases are always paired as A–T and G-C  RNA is single stranded but it still coils into a helix 24

25. Double Helix of DNA  The sister strands of the DNA molecule run in opposite directions (antiparallel)  Purine with Pyrimidine  The sister strands are complementary but not identical  The bases are joined by hydrogen bonds, individually weak but collectively strong  A-T is joined by two hydrogen bonds  G-C is joined by three hydrogen bonds

26. Complementary Base Pairs 26 Two H bonds for A-T Three H bonds for G-C

27. Double Helix of DNA 27

28. DOUBLE HELIX

29. OVERVIEW

30. Checkpoint Write the complementary base sequence for the matching strand in the following DNA section: -A-G-T-C-C-A-A-T-G-C- 30

31. Answer Write the complementary base sequence for the matching strand in the following DNA section: -A-G-T-C-C-A-A-T-G-C- -T-C-A-G-G-T-T-A-C-G- 31