Ch 10 DNA, RNA, and Protein Synthesis

1. Ch10DNA, RNA, and Protein Synthesis

3. Review • What did Mendel tell us about heredity? • Did he know what was being transmitted? • This chapter will help us identify the structure, and function of DNA.

4. 10-1 Discovery of dna10-2 structure of dna SKIP 2-3 lines between rows.

5. Griffith’s experiment • 1928 Britain • Studied Streptococcus pneumoniae • Trying to develop a vaccine • Identified two strains • virulent: disease causing • Colonies with smooth edges (S strain) • non-virulent • Colonies with Rough edges (R strain)

7. 10-1 Discovery of dna10-2 structure of dna

8. DNA “Heredity factors” = genes Genes are located on DNA molecule

9. AVERY’S EXPERIMENTS • Is transforming agent protein, RNA, or DNA??? • Used R and S strains on mice again.

10. 10-1 Discovery of dna10-2 structure of dna

11. Hershey-Chase experiment • Bacteriophage: virus that infects bacteria

12. Is DNA or protein the hereditary material viruses • transfer when they infect a bacterial cell? All viral DNA entered bacterial cell. Very little protein entered.

13. 10-1 Discovery of dna10-2 structure of dna

14. 10-2 DNA structure • 1953 • Watson and Crick identified the 3-D structure of DNA

15. Rosalind Franklin • Female scientist • Crucial final clue • X-Ray diffraction technique

16. 10-1 Discovery of dna10-2 structure of dna

17. DNA made of 2 chains that wrap around each other to form a double helix

18. DNA Nucleotides • monomer of nucleic acids • Three components • 5-Carbon sugar • Phosphate group • Nitrogenous base

19. DNA Double helix • 2 strands of DNA likened to a twisted ladder • Nitrogenous bases = “rungs” • Held together with H-Bonds between complementary nitrogenous bases • Sugar and phosphate compose “backbone” or “handrails”

20. Nitrogenous bases • Only 4 • Adenine (A) • Guanine (G) • Thymine (T) • Cytosine (C) Double ringed: Purines Single ringed: Pyrimidines

21. Complementary bases • 1949; Erwin Chargaff • %A = %T • %G = %C • Adenine always bonds with Thymine • Guanine always bonds with Cytosine • Nitrogenous bases are complementary to each other • What is the complementary strand to ATTG?

22. 10-1 Discovery of dna10-2 structure of dna

23. What is the • complementary strand to • A C C T G T G A G A C G?

24. QUIZ NEXT CLASS • MATCH THE FOLLOWING SCIENTISTS TO THEIR WORK • Frederick Griffith • Hershey & Chase • Watson & Crick • Erwin Chargaff • Structure of a NUCLEOTIDE • Structure of DNA • Purines vs. pyrimidines • Complelementary bases

25. 10-3 DNA replication • Process by which DNA is copied • In nucleus • During s phase of cell cycle prior to mitosis • Two strands of DNA separate • Each strand serves as a template(?) for new strand

27. Steps • DNA unwound by helicase • Helicase moves along DNA& breaks H-bonds b/w bases

29. Steps continued… • Nucleotides floating in nucleus • DNA Polymerase adds complementary nucleotides to original strand • Covalent bonds b/w sugar and phosphates of adjoining nucleotides • Hydrogen bonds b/w bases

32. Steps • DNA Polymerase finishes and releases DNA strands • 2 identical DNA strands result

33. DNA replication • http://www.youtube.com/watch?v=yqESR7E4b_8

34. DNA replication review • ATC GTC GAT GTA AGG • Identify the complementary bases first • Divide the two strands using one color • Using a second color, identify the new complimentary strand

35. Errors in replication • Normally very accurate • One error per 1 billion nucleotides • DNA polymerase can proofread DNA for mistakes • When found, mistake is corrected • Mutation: change in nucleotide sequence of a DNA molecule

36. Cancer • Mutation in genes that control cell division can result in uncontrolled cell growth (cancer) • Tumor: abnormal mass of cells

37. Protein synthesis • Flow of genetic information: • Genes in DNA are TRANSCRIBED into mRNA in the nucleus • mRNA is TRANSLATED in cytoplasm into a sequence of amino acids (protein) • DNA  RNA  protein transcription translation

38. RNA • DNA = DEOXYribonucleic acid • RNA = ribonucleic acid • Differences (3) • Sugar: • RNA = ribose • DNA = deoxyribose • Shape: • RNA = single stranded • DNA = double stranded • Nitrogenous bases • In RNA, replace thymine with Uracil (U)

39. Types of RNA • Messenger RNA (mRNA) • Single stranded • Carries instructions from a gene (DNA) to make protein to ribosome • Ribosomal RNA (rRNA) • Composes ribosome • Transfer RNA (tRNA) • Transfers amino acids to ribosome

41. Transcription • Process by which genetic instructions in a specific gene are re-written into mRNA • In nucleus • RNA polymerase binds to promoter • Enzyme forms RNA on a DNA template • Promoter: specific sequence of nucleotides that initiates transcription

42. Transcription 2. RNA polymerase adds free RNA nucleotides that are complementary to template strand of DNA - Remember: in RNA, replace thymine with uracil DNA strand: ATCGAC mRNA strand: UAGCUG DNA ATCGGATTACA mRNA UAGCCUAAUGU

43. Transcription • RNA pol reaches termination signal • Releases both DNA and new mRNA transcript

45. Transcription and translation • http://www.youtube.com/watch?v=41_Ne5mS2ls

46. Bellwork assignment • Take out your notes, draw, and fill in the table below

48. DNA  RNA  Protein • Up until now we’ve gone from DNA to mRNA through transcription • Now, we are going to translate the code in the mRNA into a sequence of amino acids • We are changing the language. Hence the name: Translation

49. The genetic code • Genetic code: the rules that relate how a sequence of nitrogenous bases corresponds to a particular amino acid • Nucleotides are read three nucleotides at a time to code for an amino acid • Codon: three-nucleotide sequence in mRNA that encodes an amino acid