Class Note for ECOL 320 at UA
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This 12 page Class Notes was uploaded by an elite notetaker on Friday February 6, 2015. The Class Notes belongs to a course at University of Arizona taught by a professor in Fall. Since its upload, it has received 17 views.
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Date Created: 02/06/15
Gene Expression Transcription Reminder B 39 Genes must be replicated transmitted and expressed 0 The genetic information in a gene is encoded mm 133 in the sequence of bases on one strand of DNA 2 F l 10 20 30 40 50 6O 7O 80 90 100 AcatttgcttctgacacaactgtgttcactagcaactcaaacagacaccATGGTGCACCTGACTCCTGAGGAGAAGTCTGCCGTTACTGCCCTGTGGGGC 101 AAGGTGAACGTGGATGAAGTTGGTGGTGAGGCCCTGGGCAthtggtatcaaggttacaagacaggtttaaggagaccaatagaaactgggcatgtggag 201 acagagaagactcttgggtttctgataggcactgactctctctgcctattggtctattttcccacccttagGCTGCTGGTGGTCTACCCTTGGACCCAGA Sequence Information Genes are expressed by determining the sequence information in two of the classes of molecules that do the cell s work RNA base sequence ribosomal RNA rRNA transfer RNA tRNA small nuclear RNA snRNA etc etc Protein amino acid sequence ribosomal proteins enzymes cytoskeletal proteins etc etc RNA Structure RNA is like DNA except Ribose instead of deoxyribose 0 Uracil instead of Thymine 0 Single stranded but can form double stranded regions With itself 3 2 H Deoxyribose OH H T OH in ribose of RNA Thymine Domain II Overhead lramsparencles In aconmpany Garratthrisham Biochemisrry Transparency 33 Figure 735 page 242 1995 Saunders College Publishing Siam MfsonC bkpaiks UGpaks M39smafcy The Dogma of Sequence Information Flow Sir Francis Crick Sequence information is passed from nucleic acid to nucleic acid DNA or RNA and from nucleic acid RNA only to protein but not from protein to nucleic acid mu re Ilcnllnn Q lrnnslnllnn l Drnleln IThe sense strand of DNA has the same i sequence as the RNA transcript r 41 Onlythe complementaJyIIJNA strand the S T G G T T A C A T T T G G T T G T G A G antisense strand 1s transcribed 3 A C G A A T T X C G A A G A C T G c w 5 Some people use the opposite terminology ITranscription requires a number of proteins RNA polymerase 5 to 3 only Proteins that determine what genes will be 5 transcribed and when RNA transcript DNA sense strand DNA antisense strand Transcription Starting transcription of the human globin gene 539AC 539AC 3 TG UUA339 TTA339 AATS39 AUUUGCUUCC ATTTGCTTCC TAAACGAAGG Transcribed region of Bglobin gene and the transcript The whole transcript is s 1650 bp long Transcription Visualized 1 RNA transcripts PM WWW DNA gene EM of ribosomal RNA rRNA genes of a newt Tandem repeats mimimimimi 123U123U123U123U Green arrow chromosome Red anow rRNA transcripts still attached 0 chromosome Transcription Visualized 2 EM of Chironomu polytene chromosome Compact chromatin dark areas opens up to form loops that are being transcribed into messenger RNA mRNA Diagram ofloop As transcripts elongate they combine with proteins to form globular ribonucleoprotein Higher magnification of EM Loop with proteins removed U ask3 d i xii la MAW Terminology Upstream Downstream 5 anking 3 anking lt gt 5 Transcription Start and Stop Signals Transcription Terminator 39 35 10 1 ltgt 35 sequence Pribnow box consensus consensus TTGACA TATAAT P R0 KARYOTE E coli Transcription Core Start Terminator Prower l I 1 lt gt TATA box EUKARYOTE consensus This is the simplest eukaryotic promoter Most TATAAA have additional sequences upstream and downstream that interact to determine what genes will be transcribed and when 1 RNA polymerase and other proteins bind to promoter and move ca 10 bp downstream before starting to transcribe 2 The transcriptional stop signal is often a pair of inverted repeats that encodes a hairpin loop stem and loop in the transcript All this and more may take place in lltranscription factories to which genes move to be expressed Exons are regions of genes that code for polypeptides while introns leaders and trailers do not Introns are found mainly in eukaryotes in nuclear and organelle genes SImp JLUG stop D lr l THEME u cs l all I N can I II 1 quot 39 I x IJILIEJTLFEFISCII ilJli UHEl DVDS I 5 39 f 39 quot39 quot r I I pmmarg 1 w a Lr scrl Ell 11quoturnriuliun emn 1 exam 2 eraon 3 539 anlcmg Tum intron 1 intron Tum 339T n5nlc1ng 4 l ugsiream l5 1 l5 5 njcwnstrizarn trlji39lscl39imiuli iranQE riptiEn SLEIH sign lfs 315p qunlayfsjg In genes that contain introns posttranscriptional processing consists of splicing the intron sequences out of the primary transcript and rejoining the ends The result is an mRNA that retains 5 and 3 untranslated regions 5 UTR and 3 UTR with continuous coding sequence in between A 5 cap and 3 polyA tail are added rRNAs and tRNAs are also cut out of longer transcripts The Human 3Globin Gene 101 tgtggagccacaccctagggttggccaatctactcccaggagcagggagg 51 gcaggagccagggctgggcataaaagtcagggcagagccatctattgctt 1 5 UTR AcauuugcuucugacacaacuguguucacuagcaacucaaacagacaccA 51 exon 1 UGGUGCACCUGACUCCUGAGGAGAAGUCUGCCGUUACUGCCCUGUGGGGC 101 AAGGUGAACGUGGAUGAAGUUGGUGGUGAGGCCCUGGGCAGguugguauc 151 intron 1 aagguuacaagacagguuuaaggagaccaauagaaacugggcauguggag 201 acagagaagacucuuggguuucugauaggcacugacucucucugccuauu 251 ggucuauuuucccacccuuagGCUGCUGGUGGUCUACCCUUGGACCCAGA 301 exon 2 GGUUCUUUGAGUCCUUUGGGGAUCUGUCCACUCCUGAUGCUGUUAUGGGC 351 AACCCUAAGGUGAAGGCUCAUGGCAAGAAAGUGCUCGGUGCCUUUAGUGA 401 UGGCCUGGCUCACCUGGACAACCUCAAGGGCACCUUUGCCACACUGAGUG 451 AGCUGCACUGUGACAAGCUGCACGUGGAUCCUGAGAACUUCAGGgugagu 501 intron 2 cuaugggacccuugauguuuucuuuccccuucuuuucuaugguuaaguuc 551 augucauaggaaggggagaaguaacaggguacaguuuagaaugggaaaca 601 gacgaaugauugcaucaguguggaagucucaggaucguuuuaguuucuuu 651 uauuugcuguucauaacaauuguuuucuuuuguuuaauucuugcuuucuu 701 uuuuuuucuucuccgcaauuuuuacuauuauacuuaaugccuuaacauug 751 uguauaacaaaagcaaauaucucugagauacauuaaguaacuuaaaaaaa 801 aacuuuacacagucugccuaguacauuacuauuuggaauauaugugugcu 851 uauuugcauauucauaaucucccuacuuuauuuucuuuuauuuuuaauug 901 auacauaaucauuauacauauuuauggguuaaaguguaauguuuuaaaau 951 uuugcauuuguaauuuuaaaaaaugcuuucuucuuuuaauauacuuuuuu 1001 guuuaucuuauuucuaauacuuucccuaaucucuuucuuucagggcaaua 1051 augauacaauguaucaugccucuuugcaccauucuaaagaauaacaguga 1101 uaauuucuggguuaaggcaauagcaauauuucugcauauaaauauuucug 1151 cauauaaauuguaacugauguaagagguuucauauugcuaauagcagcua 1201 caauccagcuaccauucugcuuuuauuuuaugguugggauaaggcuggau 1251 uauucugaguccaagcuaggcccuuuugcuaaucauguucauaccucuua 1301 exon 3 ucuuccucccacagCUCCUGGGCAACGUGCUGGUCUGUGUGCUGGCCCAU 1351 CACUUUGGCAAAGAAUUCACCCCACCAGUGCAGGCUGCCUAUCAGAAAGU 1401 GGUGGCUGGUGUGGCUAAUGCCCUGGCCCACAAGUAUCACuaagcucgcu 1451 3 UTR uucuugcuguccaauuucuauuaaagguuccuuuguucccuaaguccaac 1501 uacuaaacugggggauauuaugaagggccuugagcaucuggauucugccu 1551 aauaaaaaacauuuAttttcattgcaatgatgtatttaaattatttctga 1601 atattttactaaaaagggaatgtgggaggtcagtgcatttaaaacataaa 1651 gaaatgatgagctgttcaaaccttgggaaaatacactatatcttaaact
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