Basic Principles of Transcription and Translation - Computer ...

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Promoter 5′ 3′ Start point RNA polymerase 5′ 3′ Unwound DNA 5′ 3′ 5′ 3′ Rewound DNA 5′ RNA transcript 5′ Transcription unit RNA transcript DNA 1 Initiation Template strand of DNA 2 Elongation 3′ 3 Termination Completed RNA transcript 3′ 3′ 5′ 3′ 5′ 3′ 5′ 3′ 5′ 1) Initiation. After RNA polymerase binds to the promoter, the DNA strands unwind and the polymerase initiates RNA synthesis at the start point on the template strand. 2) 2) Elongation The polymerase moves downstream unwinding the DNA and elongating the RNA transcript 5’ 3’ In the wake of transcription the DNA strands re-form a double helix. 3) 3) Termination Eventually the RNA transcript is released and the polymerase detaches from the DNA The stages of transcription: initiation elongation and termination. Thus general depiction of transcription applies to both bacteria and eukaryotes but the details of termination differ, as described in the text. Also in a bacterium the transcript is immediately usable as mRNA in a eukaryote the RNA transcript must first undergo processing. Elongation Nontemplate strand of DNA RNA polymerase RNA nucleotides 3′ 3′ end 5′ 5′ Newly made RNA Direction of transcription (“downstream”) Template strand of DNA
RNA Polymerase Binding and Initiation of Transcription Promoters signal the initiation of RNA synthesis Transcription factors mediate the binding of RNA polymerase and the initiation of transcription The completed assembly of transcription factors and RNA polymerase II bound to a promoter is called a transcription initiation complex A promoter called a TATA box is crucial in forming the initiation complex in eukaryotes 5′ 3′ 5′ 3′ 1 Promoter Template 3′ 5′ TATA box Start point Template DNA strand Transcription factors RNA polymerase II 5′ 3′ 2 3 3′ 5′ Transcription factors 3′ 5′ 5′ RNA transcript Transcription initiation complex 1) A eukaryotic promoter commonly includes a TATA box a nucleotide sequence containing TATA about 25 nucleotides upstream from the transcription start point. By convention nucleotide sequences are given as they occur on the nontemplate strand 2) Several transcription factors one recognizing the TATA box must bind to the DNA before RNA polymerase II can do so. 3) Additional transcription factors (purple) bind to the DNA along with RNA polymerase II forming the transcription initiation complex. The DNA double helix then unwinds and RNA synthesis begins at the start point on the template strand. The initiation of transcription at a eukaryotic promoter. In eukaryotic cells proteins called transcription factors mediate the initiation of transcription by RNA polymerase II
Page 1 and 2: The Flow of Genetic Information Th
Page 3 and 4: TRANSCRIPTION DNA mRNA (a) Bacteria
Page 5 and 6: The Genetic Code How are the instr
Page 7 and 8: Cracking the Code All 64 codons we
Page 9: Molecular Components of Transcripti
Page 13 and 14: Eukaryotic cells modify RNA after t
Page 15 and 16: 5′ Exon Intron Exon Intron Pre-mR
Page 17 and 18: The Functional and Evolutionary Imp
Page 19 and 20: Polypeptide Trp Phe Ribosome Amino
Page 21 and 22: Amino acid P P P ATP Adenosine Amin
Page 23 and 24: Building a Polypeptide The three s
Page 25 and 26: The elongation cycle of translation
Page 27 and 28: Growing polypeptides Completed poly
Page 29 and 30: Polypeptide synthesis always begins
Page 31 and 32: Type of RNA Small nucleolar RNA (sn
Page 33 and 34: RNA polymerase RNA polymerase Polyr
Page 35 and 36: Individual bacteria respond to envi
Page 37 and 38: Eukaryotic gene expression can be r
Page 39 and 40: CYTOPLASM mRNA in cytoplasm Degrada
Page 41 and 42: Histone tails DNA double helix Amin
Page 43 and 44: Epigenetic Inheritance Although th
Page 45 and 46: The Roles of Transcription Factors
Page 47 and 48: Mechanisms of Post-Transcriptional
Page 49 and 50: Initiation of Translation The init
Page 51 and 52: Noncoding RNAs play multiple roles
Page 53: Chromatin Remodeling and Silencing

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