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Ch. 10 Notes DNA: Transcription and Translation

Ch. 10 Notes DNA: Transcription and Translation. GOALS. Compare the structure of RNA with that of DNA Summarize the process of transcription Relate the role of codons to the sequence of amino acids that results after translation Outline the major steps of translation

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Ch. 10 Notes DNA: Transcription and Translation

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  1. Ch. 10 NotesDNA: Transcription and Translation

  2. GOALS • Compare the structure of RNA with that of DNA • Summarize the process of transcription • Relate the role of codons to the sequence of amino acids that results after translation • Outline the major steps of translation • Discuss the evolutionary significance of the genetic code • Describe how the lac operon is turned on or off • Summarize the role of transcription factors in regulating eukaryotic gene expression • Describe how eukaryotic genes are organized • Evaluate three ways that point mutations can alter genetic material

  3. RNA 1. Nucleic acid made of nucleotides linked together 2. Single stranded Decoding the Information in DNA

  4. RNA 3. Contains 5C ribose sugar (one more oxygen than DNA) Decoding the Information in DNA

  5. RNA 4. Has A, G and C bases, but no T 5. Thymine replaced by uracils (which pairs with adenine) Decoding the Information in DNA

  6. Transcription Instructions for making protein are transferred from a gene to an RNA molecule Decoding the Information in DNA

  7. Translation Two types of RNA are used to read instructions on RNA molecule and put amino acids together to make the protein Decoding the Information in DNA

  8. Gene Expression Protein synthesis Protein making process based on information encoded in DNA Decoding the Information in DNA

  9. Transcription Transfers info from a gene on DNA to RNA In prokaryotes- occurs in cytoplasm In eukaryotes- occurs in nucleus TRANSCRIPTION

  10. Transcription (STEPS) 1. RNA polymerase binds to start signal “promoter” on DNA 2. RNA polymerase unwinds and opens DNA double helix TRANSCRIPTION

  11. Transcription (STEPS) 3. RNA polymerase reads genes- adds and links matching nucleotides by base pairing (A-U and G-C) TRANSCRIPTION

  12. Transcription (STEPS) 4. RNA polymerase reaches stop signal at end of gene 5. As RNA polymerase works, a single strand of RNA grows TRANSCRIPTION

  13. Transcription (STEPS) 6. DNA helix zips itself back up as RNA polymerase passes by TRANSCRIPTION

  14. Transcription (STEPS) 7. Many identical RNA molecules are made simultaneously Feather like appearance in photos TRANSCRIPTION

  15. Messenger RNA mRNA Made when cells need a protein made Delivers protein making instructions from gene to translation site Instructions written in codons The GENETIC CODE

  16. Codons Three nucleotide sequences along mRNA 64 possible codons Each corresponds to: An amino acid OR A stop signal OR A start signal The GENETIC CODE

  17. 1. During DNA replication, what molecule “reads” the strand of DNA to make the matching strand? 2. During transcription, what molecule “reads” the DNA? 3. What material does the transcription process create? Can You Tell Me?

  18. RNA’s role in translation Takes place in cytoplasm Transfer RNA (tRNA) and ribosomes help in protein synthesis The GENETIC CODE

  19. Transfer RNA tRNA Single strand, carries amino acid Folded shape Contains anticodon The GENETIC CODE

  20. Anticodon 3 nucleotides on tRNA that are complementary to a mRNA codon The GENETIC CODE

  21. Ribosomal RNA rRNA makes up part of ribosomes The GENETIC CODE

  22. Translation process 1. mRNA leaves nucleus, enters cytoplasm 2. Ribosome hooks onto mRNA at start codon The GENETIC CODE

  23. Translation process 3. tRNA attaches to ribosome subunit and binds to mRNA Anticodon of tRNA binds to codon of mRNA The GENETIC CODE

  24. Translation process 4. tRNA drops off amino acid its carrying 5. Another tRNA comes and drops an amino acid off The GENETIC CODE

  25. Translation process 6. Another tRNA enters, first tRNA leaves The GENETIC CODE

  26. Translation process 7. Each amino acid bonded to previous one to form a chain 8. tRNA detaches leaving amino acid attached to remaining tRNA The GENETIC CODE

  27. Translation process 9. Repeats until ribosomal subunit reaches stop codon 10. Newly made protein is released The GENETIC CODE

  28. TRANSLATION

  29. TRANSLATION

  30. TRANSLATION

  31. TRANSLATION

  32. TRANSLATION

  33. Assessment One • Distinguish two differences between RNA structure and DNA structure • Explain how RNA is made during transcription • Interpret the genetic code to determine the amino acid coded for by the codon CCU • Compare the roles of the three different types of RNA during translation • What is the maximum number of amino acids that could be coded for by a section of mRNA with the sequence GUUCAGAACUGU?

  34. Protein Synthesis in Prokaryotes Requires too much energy and too many materials for cell to make every protein encoded for by the DNA at all times Gene expression can be regulated according to cell needs Ex: E. coli bacteria Protein Synthesis

  35. Lac Operon 1. Lactose in dairy products enters your intestines 2. E. coli there can use lactose for nutrition (to make glucose and galactose) Regulating Protein Synthesis

  36. Lac Operon 3. Three genes for breaking down lactose located next to each other on DNA (can turn them on or off) Genes on: they’re ready to be transcribed and translated Regulating Protein Synthesis

  37. Lac Operon 4. These 3 genes turn on in presence of lactose and turn off in its absence Regulating Protein Synthesis

  38. Lac Operon 5. Operator- area on DNA (touching start/promoter) that acts as on and off switch Can block RNA polymerase from transcribing Regulating Protein Synthesis

  39. Lac Operon 6. Operon consists of Operator Promoter Three genes All work together to control lactose metabolism Regulating Protein Synthesis

  40. Lac Operon 7. No lactose present Lac operon is turned off when repressor protein binds to DNA Repressor blocks RNA polymerase from binding Regulating Protein Synthesis

  41. Lac Operon 8. In presence of lactose Lactose binds to repressor changing its shape Causes repressor to fall off DNA Allows RNA polymerase to bind and transcribe Regulating Protein Synthesis

  42. Protein synthesis in eukaryotes Most gene regulation is to control the onset of transcription (binding of RNA polymerase) Regulating Protein Synthesis

  43. Protein synthesis in eukaryotes Transcription Factors- regulatory proteins that help rearrange RNA polymerase into the correct position Regulating Protein Synthesis

  44. Intervening DNA in Eukaryotic Genes 1. Introns- longs segments of nucleotides with no coding information Break up DNA/genes Intervening DNA

  45. Intervening DNA in Eukaryotic Genes 2. Exons- actual genes that are translated into proteins Intervening DNA

  46. Intervening DNA in Eukaryotic Genes 3. After transcription, introns in mRNA are cut out by spliceosomes Exons are stitched back together Intervening DNA

  47. Intervening DNA in Eukaryotic Genes 4. Large numbers of exons and introns allows evolutionary flexibility because they can be shuffled about to make new genetic codes Intervening DNA

  48. Mutations Changes in DNA of a gene are rare When in body cells, only affect individual When in gametes, offspring can be affected Mutations

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