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遺 傳 學 Chapter 13

遺 傳 學 Chapter 13. 授課教師 賴伯琦. 基因表現. 轉錄 Transcription 轉譯 Translation. 基因表現. 轉錄 Transcription 由 DNA 的遺傳密碼轉換成 RNA 的含氮鹽基序列 轉譯 Translation. 原核生物的基因轉錄. 只有 RNA polymerase 參與. 原核生物的基因轉錄. 只有 RNA polymerase 參與 結束時是由於終結子 (Rho) 與終結序列結合 (terminator sequences) 作用，稱為 Rho-dependent terminator.

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遺 傳 學 Chapter 13

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  1. 遺 傳 學Chapter 13 授課教師 賴伯琦

  2. 基因表現 • 轉錄Transcription • 轉譯Translation

  3. 基因表現 • 轉錄Transcription • 由DNA的遺傳密碼轉換成RNA的含氮鹽基序列 • 轉譯Translation

  4. 原核生物的基因轉錄 • 只有RNA polymerase參與

  5. 原核生物的基因轉錄 • 只有RNA polymerase參與 • 結束時是由於終結子(Rho)與終結序列結合(terminator sequences)作用，稱為Rho-dependent terminator

  6. 原核生物的基因轉錄 • 只有RNA polymerase參與 • 結束時是由於終結子(Rho)與終結序列結合(terminator sequences)作用，稱為Rho-dependent terminator (type II) • 有些是沒有Rho，而是RNA上的一段序列，稱為Rho-independent terminator (type I)

  7. 4-8 AT base pairs

  8. 真核生物的基因轉錄 • 有3種RNA polymerase參與 • RNA polymerase I：轉錄 ribosome RNAs (rRNAs)，28S、18S、5.8S(S是指在離心時分子大小沈澱粗略值) • RNA polymerase II：轉錄messenger RNAs及一些small nuclear RNAs (snRNAs) • RNA polymerase III：轉錄transfer RNAs (tRNAs)、5s rRNA、及一些snRNAs

  9. RNA polymerase II from yeast

  10. TFIID 接合到 TATA box 形成 initial committed complex. 複合的multisubunit TFIID 有一個次單體(subunit)稱為 TATA-binding protein (TBP), 可以辨認TATA box sequence 還有一些蛋白質稱為TBP-associated factors (TAFs). TFIID–TATA box complex 就像一個可以和其他轉錄因子接合的位置

  11. TFIIA 和 TFIIB 接合

  12. 然後，RNA polymerase II 和 TFIIF 接合 產生 minimal transcription initiation complex. (RNA polymerase II, 如同所有真核生物 RNA polymerases, 無法直接辨認promoter elements並接合)

  13. 然後 TFIIE 和 TFIIH 接合產生complete transcription initiation complex,又稱為 preinitiation complex (PIC). TFIIH 的類解旋酶 (helicase-like) 解開promoter DNA的雙股螺旋，轉錄開始進行。

  14. Chapter 14

  15. 基因表現 • 轉錄Transcription • 由DNA的遺傳密碼轉換成RNA的含氮鹽基序列 • 轉譯Translation • 由DNA轉錄而來的RNA為Messenger RNA，由mRNA轉換成氨基酸序列 • 轉譯進行處為Ribosome RNA • 參與轉譯還有Transfer RNA

  16. Ribosome RNA

  17. E. coli核醣體(ribosome) 的模型 (70S)，包括一個小的次單體 (30S，黃色) 和一個大的次單體(50S，紅色)

  18. Transfer RNA

  19. Transfer RNA

  20. Transfer RNA

  21. Transfer RNA

  22. Amino Acid

  23. Inosine • From Wikipedia, the free encyclopedia. • Inosine is a molecule (known as a nucleoside) that is formed when hypoxanthine is attached to a ribose ring (also known as a ribofuranose) via a β-N9-glycosidic bond. This is a very common modified nucleoside found in tRNAs and is essential for proper translation of the genetic code in Wobble base pairs. • Inosine is a nucleic acid important for RNA editing. A (Adenine) is converted to I (Inosine), which pairs with G (Guanine). • Inosine is also an intermediate in a chain of purine nucleotides reactions required for muscle movements. It is currently being tested as a treatment for multiple sclerosis.

  24. Transfer RNA 如何攜帶特定氨基酸？

  25. 原核生物蛋白質合成的開始 • 在起始密碼之前有一段特殊的序列

  26. 又稱為RBS ribosome-binding site

  27. 原核生物蛋白質合成的開始 • 在起始密碼之前有一段特殊的序列 • 帶有起始密碼Methionine 的tRNA被修飾為帶有甲醛基的 fMet (formylmethionine)

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