The Ribosome Is part of the cellular machinery for translation, polypeptide synthesis

1. The Ribosome • Is part of the cellular machinery for translation, polypeptide synthesis Figure 17.1

2. Evidence from the Study of Metabolic Defects • In 1909, British physician Archibald Garrod • Was the first to suggest that genes dictate phenotypes through enzymes that catalyze specific chemical reactions in the cell

3. Nutritional Mutants in Neurospora: Scientific Inquiry • Beadle and Tatum causes bread mold to mutate with X-rays • Creating mutants that could not survive on minimal medium; each mutant was defective in a single gene supporting the one gene-one enzyme hypothesis

4. Overview: the roles of transcription and translation in the flow of genetic information No mRNA processing

5. Question: • How does RNA(ribonucleic acid) differ from DNA (deoxyribonucleic acid)?

6. RNA • ribose sugar • Nitrogenous bases: • uracil instead of thymine • U : A • C : G • single stranded • lots of RNAs • mRNA, tRNA, rRNA transcription DNA RNA

7. The “Central Dogma” • flow of genetic information within a cell transcription translation DNA RNA polypeptide replication

8. Transcription occurs when messenger RNA (mRNA) reads the DNA strand in the nucleus. It begins when RNA Polymerase breaks open the double helix and begins reading the DNA strand. Translation occurs when transfer RNA (tRNA)reads mRNA at the ribosome.

9. The triplet code

10. The dictionary of the genetic code

11. Protein Synthesis Animations: http://bcs.whfreeman.com/hillis1e/#667501__674148__ DNA and RNA Structure: http://highered.mcgraw-hill.com/sites/0072437316/student_view0/chapter15/animations.html# http://highered.mcgraw-hill.com/olc/dl/120077/micro06.swf Processing of Gene Information (Prokaryotes vs Eukaryotes): http://highered.mcgraw-hill.com/olc/dl/120077/bio25.swf RNA Splicing: http://highered.mcgraw-hill.com/sites/9834092339/student_view0/chapter15/rna_splicing.html How Splicesomes Process RNA: http://highered.mcgraw-hill.com/olc/dl/120077/bio30.swf Transcription: http://highered.mcgraw-hill.com/sites/9834092339/student_view0/chapter15/mrna_synthesis__transcription_.html http://bcs.whfreeman.com/thelifewire/content/chp12/1202001.html http://highered.mcgraw-hill.com/sites/9834092339/student_view0/chapter15/stages_of_transcription.html Translation: http://sites.fas.harvard.edu/~biotext/animations/TRANSLATE20b.swf http://highered.mcgraw-hill.com/sites/9834092339/student_view0/chapter15/how_translation_works.html http://sites.fas.harvard.edu/~biotext/animations/TRANSLATE20b.swf Translation Elongation: http://highered.mcgraw-hill.com/sites/9834092339/student_view0/chapter15/translation_elongation.html Translation Termination: http://highered.mcgraw-hill.com/sites/9834092339/student_view0/chapter15/translation_termination.html

12. DNA and Protein Synthesis Animations from the Dolan DNA Learning Center: DNA Replication (Basic):  https://www.youtube.com/watch?v=bee6PWUgPo8 DNA Replication (Advanced): https://www.youtube.com/watch?v=I9ArIJWYZHI DNA Transcription (Basic): https://www.youtube.com/watch?v=5MfSYnItYvg DNA Transcription (Advanced): https://www.youtube.com/watch?v=SMtWvDbfHLo mRNA Translation (Basic):  https://www.youtube.com/watch?v=8dsTvBaUMvw mRNA Translation (Advanced):  https://www.youtube.com/watch?v=TfYf_rPWUdY

13. The stages of transcription: initiation, elongation, and termination

14. The initiation of transcription at a eukaryotic promoter

15. RNA processing; addition of the 5 cap and poly(A) tail

16. The function of the cap is: • prevent mRNA degradation by hydrolytic enzymes • helps attach to the ribosome • Function of the 3’ tail: • same functions as the 5’cap • also helps facilitate export of mRNA from nucleus

17. RNA processing: RNA splicing

18. The roles of snRNPs and spliceosomes in mRNA splicing

19. RNA Splicing • Removes noncoding regions called introns • snRNPs (small nuclear ribonucleoproteins) recognize the splicing signals that are at the ends of introns • The RNA in the snRNP is called snRNA (small nuclear RNA) • spliceosomes are the larger protein assemblies formed by the joining of snRNPs

20. Correspondence between exons and protein domains

21. The structure of transfer RNA (tRNA)

22. The structure of transfer RNA (tRNA)

23. Translation: the basic concept

24. An aminoacyl-tRNA synthetase joins a specific amino acid to a tRNA

25. The anatomy of a functioning ribosome

26. The initiation of translation

27. The elongation cycle of translation

28. The termination of translation

29. Peptide Bonds Join Amino Acids

30. Polyribosomes

31. Coupled transcription and translation in bacteria

32. The signal mechanism for targeting proteins to the ER

33. The polypeptides of proteins destined for the endomembrane system are marked by a signal peptide, which targets the protein to the ER. A signal recognition particle (SRP) functions as an adaptor that brings the ribosome to a receptor protein built into the ER membrane.

34. Mutations – a change in the genetic material or DNA; most are neutral and have little effect on expression of genes.

35. Point Mutations – occur at a single point in a DNA sequence A Frameshift Mutation changes the “reading frame” of the genetic message.

36. Categories and Consequences of Point Mutations: Base-Pair Substitution

37. The molecular basis of sickle-cell disease: a point mutation

38. The Primary Structure of a Protein

39. Categories and consequences of point mutations: Base-pair insertion or deletion

40. A summary of transcription and translation in a eukaryotic cell

41. The ___________ on tRNA is complementary to the ___________ on mRNA.

42. Distinguish between a frameshift mutation and a point mutation. How could a Frameshift Mutation lead to Missense or Nonsense codons?

43. What is the difference between a mutagen and a carcinogen? What is the role of the signal-recognition particle?

44. Distinguish between the roles of each of the three sites located within the ribosome.

45. List three major differences between the transcription process in prokaryotes vs. eukaryotes.

46. Translation mRNA tRNA A U U A G C C G Transcription DNA mRNA A U T A G C C G Put this in your notebook!

47. Transcription takes place in the _______ of the cell when mRNA copies the _____ strand. Translation takes place in the _______ of the cell when tRNA copies the _______ strand at the __________ (organelle).

48. 4) Describe what happens in the nucleus in the RNA editing process.

49. 1) If a DNA sequence reads A-T-T-C-G-C what are the complementary mRNA and tRNA sequences? 2) Every three bases on mRNA is called a/an _______ and codes for a specific __________ __________. 3) AUG codes for: CUA codes for:

50. If a DNA strand has the bases A-T-C-G-T-C, what is the complementary mRNA codon and tRNA anticodon?