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Fig. 17-4 DNA molecule Gene 2 Gene 1 Gene 3 DNA template strand TRANSCRIPTION mRNA Codon TRANSLATION Protein Amino acid Third mRNA base (3 end of codon) First mRNA base (5 end of codon) Fig. 17-5 Second mRNA base Fig. 17-7 Promoter Transcription unit 5 3 Start point RNA polymerase 3 5 DNA 1 Initiation 5 3 RNA transcript RNA polymerase Template strand of DNA 3 2 Elongation Rewound DNA 5 3 RNA nucleotides 3 5 Unwound DNA 3 5 5 5 Direction of transcription (“downstream”) 3 Termination 3 5 5 3 5 3 end 5 3 RNA transcript Nontemplate strand of DNA Elongation Completed RNA transcript 3 Newly made RNA Template strand of DNA Fig. 17-7a-1 Promoter Transcription unit 5 3 Start point RNA polymerase DNA 3 5 Fig. 17-7a-2 Promoter Transcription unit 5 3 Start point RNA polymerase 3 5 DNA 1 Initiation 5 3 Unwound DNA 3 5 RNA transcript Template strand of DNA Fig. 17-7a-3 Promoter Transcription unit 5 3 Start point RNA polymerase 3 5 DNA 1 Initiation 5 3 3 5 Unwound DNA RNA transcript Template strand of DNA 2 Elongation Rewound DNA 5 3 3 5 RNA transcript 3 5 Fig. 17-7a-4 Promoter Transcription unit 5 3 Start point RNA polymerase 3 5 DNA 1 Initiation 5 3 3 5 Unwound DNA RNA transcript Template strand of DNA 2 Elongation Rewound DNA 5 3 3 5 3 5 RNA transcript 3 Termination 5 3 3 5 5 Completed RNA transcript 3 Fig. 17-7b Nontemplate strand of DNA Elongation RNA polymerase 3 RNA nucleotides 3 end 5 5 Direction of transcription (“downstream”) Newly made RNA Template strand of DNA Fig. 17-8 1 Promoter A eukaryotic promoter includes a TATA box Template 5 3 3 5 TATA box Start point Template DNA strand 2 Transcription factors Several transcription factors must bind to the DNA before RNA polymerase II can do so. 5 3 3 5 3 Additional transcription factors bind to the DNA along with RNA polymerase II, forming the transcription initiation complex. RNA polymerase II Transcription factors 5 3 3 5 5 RNA transcript Transcription initiation complex Fig. 17-9 5 G Protein-coding segment Polyadenylation signal 3 P P P 5 Cap AAUAAA 5 UTR Start codon Stop codon 3 UTR AAA…AAA Poly-A tail Fig. 17-10 5 Exon Intron Exon Exon Intron 3 Pre-mRNA 5 Cap Poly-A tail 1 30 31 Coding segment mRNA 5 Cap 1 5 UTR 104 105 146 Introns cut out and exons spliced together Poly-A tail 146 3 UTR Fig. 17-11-1 RNA transcript (pre-mRNA) 5 Exon 1 Protein snRNA Intron Exon 2 Other proteins snRNPs Fig. 17-11-2 RNA transcript (pre-mRNA) 5 Exon 1 Intron Protein snRNA Other proteins snRNPs Spliceosome 5 Exon 2 Fig. 17-11-3 RNA transcript (pre-mRNA) 5 Exon 1 Intron Protein snRNA Exon 2 Other proteins snRNPs Spliceosome 5 Spliceosome components 5 mRNA Exon 1 Exon 2 Cut-out intron Fig. 17-14a 3 Amino acid attachment site 5 Hydrogen bonds Anticodon (a) Two-dimensional structure Fig. 17-17 3 U A C 5 5 A U G 3 Initiator tRNA Large ribosomal subunit P site GTP GDP E mRNA 5 Start codon mRNA binding site 3 Small ribosomal subunit 5 A 3 Translation initiation complex Fig. 17-18-1 Amino end of polypeptide E 3 mRNA 5 P A site site Fig. 17-18-2 Amino end of polypeptide E 3 mRNA 5 P A site site GTP GDP E P A Fig. 17-18-3 Amino end of polypeptide E 3 mRNA 5 P A site site GTP GDP E P A E P A Fig. 17-18-4 Amino end of polypeptide E 3 mRNA Ribosome ready for next aminoacyl tRNA P A site site 5 GTP GDP E E P A P A GDP GTP E P A Fig. 17-19-1 Release factor 3 5 Stop codon (UAG, UAA, or UGA) Fig. 17-19-2 Release factor Free polypeptide 3 5 5 Stop codon (UAG, UAA, or UGA) 3 2 GTP 2 GDP Fig. 17-19-3 Release factor Free polypeptide 5 3 5 5 Stop codon (UAG, UAA, or UGA) 3 2 GTP 2 GDP 3 Fig. 17-20 Growing polypeptides Completed polypeptide Incoming ribosomal subunits Start of mRNA (5 end) (a) End of mRNA (3 end) Ribosomes mRNA (b) 0.1 µm Fig. 17-21 Ribosome mRNA Signal peptide Signal peptide removed Signalrecognition particle (SRP) CYTOSOL ER LUMEN Translocation complex SRP receptor protein ER membrane Protein Fig. 17-22 Wild-type hemoglobin DNA Mutant hemoglobin DNA C T T C A T 3 5 3 G T A 5 G A A 3 5 mRNA 5 5 3 mRNA G A A Normal hemoglobin Glu 3 5 G U A Sickle-cell hemoglobin Val 3 Fig. 17-23 Wild-type DNA template strand 3 5 5 3 mRNA 5 3 Protein Stop Amino end Carboxyl end A instead of G 3 5 Extra A 5 3 U instead of C 5 5 3 3 5 Extra U 3 5 3 Stop Stop Silent (no effect on amino acid sequence) Frameshift causing immediate nonsense (1 base-pair insertion) T instead of C missing 3 5 5 3 3 5 5 3 A instead of G missing 3 5 5 3 Stop Missense Frameshift causing extensive missense (1 base-pair deletion) missing A instead of T 3 5 5 3 3 5 3 5 U instead of A 5 5 3 missing Stop Stop Nonsense (a) Base-pair substitution 3 No frameshift, but one amino acid missing (3 base-pair deletion) (b) Base-pair insertion or deletion Fig. 17-23a Wild type DNA template 3 strand 5 5 3 mRNA 5 3 Protein Stop Amino end Carboxyl end A instead of G 5 3 3 5 U instead of C 5 3 Stop Silent (no effect on amino acid sequence) Fig. 17-23b Wild type DNA template 3 strand 5 5 3 mRNA 5 3 Protein Stop Amino end Carboxyl end T instead of C 5 3 3 5 A instead of G 3 5 Stop Missense Fig. 17-23c Wild type DNA template 3 strand 5 5 3 mRNA 5 3 Protein Stop Amino end Carboxyl end A instead of T 3 5 5 3 U instead of A 5 3 Stop Nonsense Fig. 17-23d Wild type DNA template 3 strand 5 5 3 mRNA 5 3 Protein Stop Amino end Carboxyl end Extra A 5 3 3 5 Extra U 5 3 Stop Frameshift causing immediate nonsense (1 base-pair insertion) Fig. 17-23e Wild type DNA template 3 strand 5 5 3 mRNA 5 3 Protein Stop Amino end Carboxyl end missing 5 3 3 5 missing 5 3 Frameshift causing extensive missense (1 base-pair deletion) Fig. 17-23f Wild type DNA template 3 strand 5 5 3 mRNA 5 3 Protein Stop Amino end Carboxyl end missing 5 3 3 5 missing 5 3 Stop No frameshift, but one amino acid missing (3 base-pair deletion) Fig. 17-25 DNA TRANSCRIPTION 3 RNA polymerase 5 RNA transcript RNA PROCESSING Exon RNA transcript (pre-mRNA) Intron Aminoacyl-tRNA synthetase NUCLEUS Amino acid CYTOPLASM AMINO ACID ACTIVATION tRNA mRNA Growing polypeptide 3 A Activated amino acid P E Ribosomal subunits 5 TRANSLATION E A Codon Ribosome Anticodon