1. Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings PowerPoint Lectures for Biology, Seventh Edition Neil Campbell and Jane Reece Lectures by Chris Romero Chapter 17 From Gene to Protein

2. Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings Basic Principles of Transcription and Translation Transcription = DNA  mRNA (mRNA = messenger RNA) Translation = mRNA  polypeptide – Occurs on ribosomes

3. Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings Basic Principles of Transcription and Translation Transcription = DNA  mRNA (mRNA = messenger RNA) Translation = mRNA  polypeptide – Occurs on ribosomes DNA  mRNA  polypeptide

4. Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings Prokaryotes – Transcription and translation occur together Figure 17.3a

5. Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings Eukaryotes - Transcription occurs in nucleus

6. Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings Eukaryotes - RNA transcripts are modified before becoming true mRNA

7. Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings Eukaryotes - Translation occurs in cytoplasm

8. Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings Cellular chain of command – DNA  RNA  amino acid (protein)

9. Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings Codons: Triplets of Bases

10. Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings Codons: Triplets of Bases Codon

11. Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings Codons: Triplets of Bases

12. Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings Cracking the Code Codon = 1. Translated into an amino acid 2. Serves as a translational start/stop signal

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14. DNA sequences in gene: 1.CCTCAGAGTGTG 2.TACGTTGCGCCC TRANSCRIPTION RNA sequence = ? TRANSLATION Amino acid sequence = ?

15. Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings Codons must be read in the correct reading frame Ex: “The red dog ate the cat” – Change reading frame “her edd oga tet hec at”

16. Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings Concept 17.2: Transcription DNA  RNA: a closer look

17. Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings RNA synthesis Catalyzed by RNA polymerase 1. Pries the DNA strands apart 2. Adds and Hooks together the RNA nucleotides

18. Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings Synthesis of an RNA Transcript 3 stages of transcription: 1. Initiation 2. Elongation 3. Termination

19. Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings 1. Initiation

20. Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings Initiation

21. Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings 2. Elongation

22. Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings 3. Termination

23. Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings Synthesis of an RNA Transcript

24. Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings Transcription Elongation

25. Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings 3 steps of transcription 1. Initiation –more specific in Eukaryotes 2. Elongation 3. Termination

26. Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings Initiation of Transcription Prokaryote Vs. Eukaryote Promoters: Prok. = RNA Pol Bind to promoter sequence Euk. = Transcription factors bind first to TATA box  then RNA pol II binds

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28. Concept 17.4 Translation = RNA directed synthesis of a polypeptide mRNA  polypeptide

29. Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings Translation Takes place in the cytoplasm Ribosome attaches to an mRNA Codon mRNA message  polypeptide by tRNA

30. Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings tRNA- transfer RNA: 1. specific amino acid attachment site 2. base triplet called an anticodon on one end ANTI-CODON Amino acid attachment site

31. Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings tRNA- transfer RNA: 1. specific amino acid attachment site 2. base triplet called an anticodon on one end Anti-Codon? Amino acid? GGA

32. Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings tRNA- transfer RNA: 1. specific amino acid attachment site 2. base triplet called an anticodon on one end CCU Glycine GGA

33. Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings Ribosomes have 2 subunits (small + large) Hold the tRNA and mRNA close together during translation Large Subunit Small Subunit tRNA binding sites mRNA binding site AP EPA

34. Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings Building a Polypeptide We can divide translation into three stages – Initiation – Elongation – Termination

35. Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings Initiation mRNA, tRNA, and ribosome subunits assemble

36. Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings Elongation: step 1- codon recognition 1 2 1 2

37. Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings Elongation: Step 2- peptide bond formation 1 2 2 2 1 1

38. Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings Elongation: 1 2 21

39. Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings Elongation: Step 3- translocation 1 2 21 3 2 1 2

40. Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings Termination of Translation: Step 3 Ribosome reaches a stop codon in the mRNA Release Factor

41. Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings Concept 17.7 Mutations- changes in the genetic material of a cell – Point mutations changes in just one base pair of a gene

42. Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings Normal Figure 17.23

43. Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings Figure 17.23 Normal Point Mutation

44. Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings Types of Point Mutations Point mutations – Base-pair substitutions – Base-pair insertions or deletions

45. Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings Substitutions A base-pair substitution – Can cause missense or nonsense Figure 17.24

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48. Missense

49. Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings Nonsense

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51. Insertions and Deletions Insertions and deletions – Are additions or losses of nucleotide pairs in a gene – May produce frameshift mutations Figure 17.25

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54. Review Transcription: DNA  mRNA Promoter, TATA box, Transcription factors, RNA Polymerase Translation: mRNA  polypeptide Small and Large ribosome subunits, mRNA, tRNA, amino acids, EPA sites

55. Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings Review Ch 17: Transcription and Translation Transcription: 3 stages Initiation, elongation, termination mRNA processing Translation : 3 stages Initiation, elongation, termination DNA mutations