Nucleic acids

1. Nucleic acids • Nucleic acids: • Maintain genetic information • Determine Protein Synthesis • DNA = deoxyribonucleic acid • “Master Copy” for most cell information. • Template for RNA • RNA = ribonucleic acid • Transfers information from DNA • Template for Proteins

2. Nucleic Acids • Chromosomes • (in nucleus) Have genes 1 gene 1 enzyme Enzymes determine external & internal characteristics

3. NUCLEIC ACIDS • Long chains (polymers) of repeating nucleotides. • Each nucleotide has 3 parts: A heterocyclic Amine Base A sugar A phosphate unit

4. Nucleotide = phosphate + sugar + base Phosphate Base Sugar -N-glycosidic linkage Nucleoside = sugar + base

5. Nucleic Acids • Nucleic Acids = polymers of Nucleotides. base B B B B B B P S P S P S P S P S P S phosphate sugar

6. O O HOCH2 HOCH2 OH OH H H H H H H H H OH OH OH H THE SUGAR PART • The major difference between RNA and DNA is the different form of sugar used. Ribose C5H10O5 in RNA DeoxyRibose C5H10O4 in DNA The difference is at carbon #2.

7. A double ring (6 & 5 members) A single ring (6 membered) The Nitrogenous Bases • 5 bases used fall in two classes • Purines & Pyrimidines

8. The Nitrogenous Bases Purines: • Pyrimidines: Adenine (A) Guanine (G) Thiamine (T) In DNA only Uracil (U) In RNA only Cytosine (C)

9. Nucleotides Di- & Tri- Phosphates Adenine ribose Adenosine 5’-monophosphate (AMP)

10. Nucleotides Di- & Tri- Phosphates Adenine ribose Adenosine 5’-monophosphate (AMP) Adenosine 5’-diphosphate (ADP)

11. Nucleotides Di- & Tri- Phosphates Adenine Adenosine 5’-triphosphate (ATP) ribose Adenosine 5’-monophosphate (AMP) Adenosine 5’-diphosphate (ADP)

12. Primary structure

13. Primary structure Adenine (A) Similar to proteins with their peptide bonds and side groups. 5’ Guanine (G) Thymine (T) Phosphate bonds link DNA or RNA nucleotides together in a linear sequence. 3’

14. H - N N O | | N - H N N N N O | | N - H H3C H H O | | N | N - H N N N O | | N N Base pairing and hydrogen bonding guanine cytosine thymine adenine

15. DNA - Secondary Structure Complementary Base Pairing Position of H bonds and distance match with:

16. C G T A G C C G A T Hydrogen bonding Each base wants to form either two or three hydrogen bonds. That’s why only certain bases will form pairs.

17. Sugar-phosphate backbone DNA coils around outsideof attached bases like a spiral stair case. Results in a double helix structure.

18. The double helix One complete twist is 3.4 nm The combination of the stairstep sugar-phosphate backbone and the bonding between pairs results in a double helix. 2 nm between strands Distance between bases = 0.34 nm

19. DNA - Secondary Structure • Complementary Base Pairing

20. Crick and Watson • (1962 Nobel Prize) • Proposed the basic structure of DNA • 2 strands wrap around each other • Strands are connected by H-bonds between the amines. • Like steps of a spiral staircase

21. Chromosomes Chromosomes consists of DNA strands coiled around protein - histomes. The acidic DNA’s are attracted to the basic histones.

22. It also was clear in the 1960s that the chromosomes of cells

23. Chromosomes • The normal number of chromosome pairs varies among the species. • Animal Pairs Plant Pairs • Man 23 Onion 8 • Cat 30 Rice 14 • Mouse 20 Rye 7 • Rabbit 22 Tomato 12 • Honeybee, White pine 12 • male 8 Adder’s 1262 • female 16 tounge fern

24. S S P P S P P P S S P S A G T C C G T C G A DNA: Self - Replication

25. S S P P S P P P S S P S A G T C C G T C C G G A DNA: Self - Replication

26. Replication of DNA Replication occurs on both halves in opposite directions.

27. DNA Replication

28. RNA synthesis In the first step, RNA polymerase binds to apromotor sequence on the DNA chain. This insures that transcription occurs in the correct direction. The initial reaction is to separate the two DNA strands.

29. RNA synthesis initiation sequence termination sequence ‘Special’ base sequences in the DNA indicate where RNA synthesis starts and stops.

30. RNA synthesis Once the termination sequence is reached, the new RNA molecule and the RNA synthase are released. The DNA recoils.

31. The messenger RNA (mRNA) move outside the nucleus to the cytoplasm where Ribosomes are anxiously awaiting their arrival. 60 S rRNA 40 S rRNA Nucleus

32. The messenger RNA (mRNA) move outside the nucleus to the cytoplasm where Ribosomes are anxiously awaiting their arrival. 60 S rRNA 40 S rRNA Nucleus

33. The messenger RNA (mRNA) move outside the nucleus to the cytoplasm where Ribosomes are anxiously awaiting their arrival. 60 S rRNA 40 S rRNA Nucleus

34. The messenger RNA (mRNA) move outside the nucleus to the cytoplasm where Ribosomes are anxiously awaiting their arrival. 60 S rRNA 40 S rRNA Nucleus

35. 60 S rRNA 40 S Ribosomal RNA – rRNA: Platform for protein synthesis. Holds mRNA in place and helps assemble proteins. rRNA

36. 60 S UUG AUG GCU AUG 3’ 5’ • The Ribosomes are like train stations • The mRNA is the train slowly moving through the station. rRNA Codons mRNA rRNA 40 S

37. Transfer RNA - tRNA = • relatively small compared to other RNA’s (70-90 bases.) • transports amino acids to site of protein synthesis.

38. Anticodons on t-RNA Site of amino acid attachment Point of attachment to mRNA Three base anticodon site

39. Amino acid codons alanine GCA, GCC, GCG GCU, AGA, AGG arginine AGA, AGG, CGA CGC, CGG, CGU asparagine AAC, AAU aspartate GAC, GAU cysteine UGC, UGU glutamate GAA, GAG glutamine CAA, CAG glycine GAA, GCC, GGG GGU histidine CAC, CAU isoleucine AUA, AUC, AUU leucine CUA, CUC, CUG CUU, UUA, UUG lysine AAA, AAG methionine AUG phenylalanine UUC, UUU proline CCA, CCC CCG, CCU serine UCA, UCC UCG, UCU AGC, AGU threonine ACA, ACC ACG, ACU tryptophan UGG tyrosine UCA, UCU valine GUA, GUC GUG, GUU

40. activated AA fMET anticodon C A G Protein Synthesis1: Activation • Each AA is activated by reacting with an ATP • The activated AA is then attached to particular tRNA... (with the correct anticodon)

41. fMET 60S U C A mRNA UUG AUG GCU AUG 3’ Psite A site 5’ Translation Initiation factors 40S ribosome unit

42. Ala fMET C A G U C A mRNA UUG AUG GCU AUG 3’ 5’ Translation 60S Psite A site 40S ribosome unit

43. peptide bond forms Ala fMET mRNA C A G U C A UUG AUG GCU AUG 3’ 5’ Translation ribosome unit

44. Amino Acid peptide bond Ala Z Z Z mRNA C A G U U C C A A G GCU U UUC UUG 3’ A 5’ Translation Met ribosome unit

45. peptide bond forms Ala ??? mRNA C A ? ? G ? U C A G GCU U UUC UUG 3’ A 5’ Translation Met ribosome unit

46. Recombinant DNA Bacterium Remove gene segment sticky ends DNA Plasmid Cut gene for insulin Replace in bacterium

47. Learning Check What is the sequence of bases in mRNA produced from a section of the template strand of DNA that has the sequence of bases: 3’–C–T–A–A–G–G–5’? 1. 5’–G–A–T–T–C–C–3’ 2. 5’–G–A–U–U–C–C–3’ 3. 5’–C–T–A–A–G–G–3’

48. Solution What is the sequence of bases in mRNA produced from a section of the template strand of DNA that has the sequence of bases: 3’–C–T–A–A–G–G–5’? 3’–C–T–A–A–G–G–5’? 2. 5’–G–A–U–U–C–C–5’

49. Learning Check The following section of DNA is used to build a mRNA for a protein. 3’—GAA—CCC—TTT—5’ A. What is the corresponding mRNA sequence? B. What are the anticodons on the tRNAs? C. What is the amino acid order in the peptide?

50. Solution 3’—GAA—CCC—TTT—5’ DNA A. What is the corresponding mRNA sequence? 5’—CUU—GGG—AAA—3’ mRNA B. What are the anticodons for the tRNAs? mRNA codonsCUU GGG AAA tRNA anticodons GAA CCC UUU C. What is the amino acid order in the peptide? mRNA 5’—CUU—GGG—AAA—3’ Leu — Gly — Lys