1. Notes on Nucleic Acids 2 types of nucleic acids: DNA – deoxyribonucleic acid RNA – ribonucleic acid Chapter 8

2. organic compounds large, made of subunits called nucleotides  Click image for interactive journey into human DNA

3. Each DNA nucleotide is made up of 3 parts: 1. Phosphate group 2. Deoxyribose – 5 carbon sugar 3. Nitrogen base – either adenine, thymine, cytosine, or guanine

5. Nitrogen bases Purines – adenine (A) and guanine (G)

6. Pyrimidines – thymine (T) and cytosine (C)

7. The bases are held together by weak hydrogen bonds Base pairings in DNA:A – T C – G

8. A model of DNA was constructed in 1953 at Cambridge University in England

9. Scientist – James Watson, (1951-1953)James Watson Field of study – biology Country - America

10. Scientist – Francis Crick (1951-1953)Francis Crick Field of study – biophysics Country - England

11. Their model is described as a double twisted helix (looks like a twisted ladder) Watson and Crick published their proposed DNA double helical structure in a paper in the journal Nature in April 1953. In this paper Watson and Crick acknowledged that they had been "stimulated by.... the unpublished results and ideas" of Wilkins and Franklin.

12. Scientist – Maurice Wilkins, (1950-1953)Maurice Wilkins Field of study – biophysics Country - England

13. Scientist – Rosalind Franklin, (1951-1953)Rosalind Franklin Field of study – Molecular Biology (x-ray diffraction) Country - England  Click image for interpret- ation of the X-ray

14. The process by which DNA builds an exact copy of itself - replication first the double helix must be unwound – this is done by enzymes called helicases then DNA polymerases (enzymes which move along each DNA strand) add nucleotides to the exposed bases

16. Replication occurs every time a cell divides, therefore passing the DNA code on into every cell

17. Genes are the DNA-encoded information that specifies particular proteins; Each gene is made of a specific sequence of nucleotides

18. The working structures of genes are made of RNA RNA structure: 1. Consists of a single strand of nucleotides

19. 2. Ribose – a 5 carbon sugar 3. Uracil (U) instead of thymine (T) uracil is paired with adenine

21. RNA base pairings:A – U C – G

22. Three types of RNA 1. mRNA – messenger RNA 2. tRNA – transfer RNA 3. rRNA – ribosomal RNA All are needed for processing the information from DNA into proteins (gene expression)

23. Differences in DNA and RNA: DNARNA 1. double stranded single stranded 2. thymine uracil 3. nucleus only cytoplasm 4. deoxyribose sugar ribose sugar

24. Gene expression occurs in two stages: 1. Transcription – information in DNA is transferred to mRNA 2. Translation – the information in mRNA is used to make a protein

25. Roles of DNA & RNA in transmitting genetic information Story time: the analogy… Comp Book– Draw the Flow Map: DNA expression in the cell You need your pencil plus three colors: –Pencil will draw cell membrane/ cell parts/ labels –RED: DNA molecules –BLUE: any RNA molecules –PURPLE: protein

26. DNA  RNA

27. RNA  protein

28. 1. Transcription (DNA  RNA) occurs in nucleus begins with the enzyme RNA polymerase which binds to the promoter

30. Promoter – a specific sequence of DNA that acts as a “start” signal for transcription Terminator – a sequence of bases that tells the RNA polymerase to stop adding nucleotides

31. Transcription Video

32. mRNA – is an RNA copy of a gene used as a blueprint for a protein carries hereditary information from DNA and delivers it to the site of translation acts as a template for the assembly of amino acids

33. tRNA – acts as an interpreter molecule translating mRNA sequences into amino acid sequences

35. rRNA – plays a structural role in ribosomes

36. 2. Translation (RNA  proteins) occurs in cytoplasm @ a ribosome —both free ribosomes & ribosomes attached to ER uses nucleic acids to synthesize proteins

37. involves all three RNA types: —rRNA in the ribosome

38. —mRNA containing the genetic message —message is made of codons AUG-AAA-UAC-CCU-CCA-GCG-GGA

39. Codon – a series of three-nucleotide sequences each codon corresponds to an amino acid or signifies a start or stop signal Write this down!

40. —tRNA carrying specific amino acids to be joined a.a.

41. AUG-AAA-UAC-CCU-CCA-GCG-GGA mRNA  tRNA UAC tRNA GGA AUG GGU Pro tRNA UUU ribosome Met Lys Tyr Ser Translation (Example) Growing polypeptide         

42. Translation: mRNA, tRNA & rRNA in cooperative action …to make proteins!!!

43. AUG-AAA-UAC-CCU-CCA-GCG-GGA mRNA  tRNA UAC tRNA GGA AUG GGU Pro tRNA UUU ribosome Met Lys Tyr Ser Translation (Repeated) Growing polypeptide         

44. Translation Video

46. A “Polysome” Can you ID the 3 RNAs?

47. Awesome summary video from www.youtube.com www.youtube.com Click here to viewhere