Week 5: Transcription and Translation

StudyBlue printing of Week 5: Transcription and Translation html, body, div, span, applet, object, iframe, h1, h2, h3, h4, h5, h6, p, blockquote, pre, a, abbr, acronym, address, big, cite, code, del, dfn, em, font, img, ins, kbd, q, s, samp, small, strike, strong, sub, sup, tt, var, b, u, i, center, fieldset, form, label, legend, table, caption, tbody, tfoot, thead, tr, th, td { margin: 0; padding: 0; border: 0; outline: 0; font-size: 100%; background: transparent; } body { line-height: 1; } blockquote, q { quotes: none; } blockquote:before, blockquote:after, q:before, q:after { content: ''; content: none; } /* remember to define focus styles! */ :focus { outline: 0; } /* remember to highlight inserts somehow! */ ins { text-decoration: none; } del { text-decoration: line-through; } /* tables still need 'cellspacing="0"' in the markup */ table { border-collapse: collapse; border-spacing: 0; } /* end RESET */ .header { min-width:800px; } .logo { padding:6px 20px 2px 20px; margin:0; font-size:25px; font-weight:bold; color:#808285; position:relative; border-bottom: 1px solid #c5c5c5; } .logo-blue { color:#70adc4; } .logo-desc { font-weight:normal; font-size:19px; color:#cccccc; margin-top:50px; position:absolute; display: none; } .back-button { position:absolute; top:20px; right:20px; font-size:13px; line-height:25px; color:rgb(0,175,225); font-weight:normal; } .back-button a { color:rgb(0,175,225); } .instructions { padding:0; margin:0; width:100%; position:relative; color:rgb(100,100,100); } .step-holder { border-left:1px solid #ededed; margin-left:20px; } .steps { padding:15px 0; float:left; width:24%; border-right:1px solid #ededed; text-align:center; } .steps-01 { } .steps-02 { } .steps-03 { } .steps-04 { } .label { padding:5px 10px; } .print-button { } .print-button a { background-color:rgb(0,175,225); color:white; line-height: 19px; padding:9px 8px 5px 30px; font-size:14px; text-decoration:none; background-image: url(images/printer.png); background-repeat: no-repeat; background-position: 7px 50%; -moz-border-radius: 5px; -webkit-border-radius: 5px; } .print-button a:hover { background-color:black; } .theNote .content { width: 8.0in !important; margin: 5px auto; padding:20px; background-color:white; } .theNote .header { border-bottom: 1px dashed #C8C8C8; font-size: 17px; padding: 0 0 10px; line-height: 19px; color: #00ADE1; min-width:500px; } .theNote .body { font-size: 14px; line-height: 19px; padding: 10px 0; } .theNote{ padding:6px 0; clear:both; background-color: rgb(200,200,200); } .theNote h3{ color: rgb(100,100,100); } .theNote h1, .theNote h3{ background-color:white; padding:2px 20px; width:8.0in !important; margin: 0 auto; font-size: 15px; } .theNote h1{ padding-top: 10px; font-size: 15px; } .theNote h1:first-child{ font-size: 20px; } .theNote h3 { font-size: 14px; font-weight: normal; } #options { border: 3px double #ccc; padding: 5px 12px; margin: 10px 50px 10px 20px; float: left; } #info { border-top: 1px solid #ccc; padding-top: 5px; font-style: italic; } li { margin: 5px 10px 5px 25px; } ul li { list-style: disc; } ol li { list-style: decimal; } img { border: 0; } table { clear: both; width: 100%; border: 1px solid #c5c5c5; border-width: 1px 0; margin: 0; page-break-after: always; } table#page { page-break-after: auto; } td { text-align: center; font-size: 12px; border-bottom: 1px dashed #c5c5c5; height: 1.75in; width: 50%; padding-left: 15px; } .leftside { border-right: 1px solid #cccccc; padding: 0 15px 0 0; } .bottom td { border-bottom: none; } .clearfix { clear:both; line-height:1px; height:1px; } img { max-width:80%; max-height:150px; margin:20px; } @media print {.header { display: none; } .content .header{ display:inherit; } table { border: 1px dashed #bbb; border-width: 1px 0; } .theNote{ background-color:white; } } THE RELATIONSHIP BETWEEN GENES AND PROTEINS Beadle and Tatum experiment: Neurospora spores cannot grow on minimal medium -irradiate spores to check for mutations that cause cells to lack enzyme -one gene-one enzyme hypothesis: genes carry info for a particular enzyme sickle cell anemia: Vernon Ingram (1956) -cleave hemoglobin, use paper chromatography for normal/sickle cells to check for differences -substitution of valine for glutamic acid mRNA: small, mobile nucleic acid that passes into cytoplasm, incorporate amino acids in order, amplify cell synthetic output rRNA: structural support, catalyze reaction where aa are covalently linked to one another tRNA: translate info in mRNA into aa "alphabet" of polypeptide rRNA, tRNA have complex secondary and tertiary structures due to folding -nonstandard base pairs, modified nitrogenous bases in addition to regular bp small nuclear RNA (snRNA) small nucleolar RNA (snoRNA) small interfering RNA (siRNA) microRNA (miRNA) AN OVERVIEW OF TRANSCRIPTION IN BOTH PROKARYOTIC AND EUKARYOTIC CELLS DNA-dependent RNA polymerase (RNA polymerase) -bind to promoter site on DNA, -transcription factors help RNA to recognize where promoter is -move in 3'-5' direction to assemble complementary RNA strand from 5'-3' -need synthesize of nucleic acids/proteins to be irreversible, pyrophosphate hydrolyzed to inorganic phosphate to release free energy, irreversible incorporation of nucleotides transcription in prokaryotes: -RNA polymerase form core enzyme, bind to DNA to synthesize RNA sigma factor helps transcription to begin at selected locations, increase enzyme affinity for promoter sites in DNA -transcriptional elongation complex: enzyme changes in conformation after incorporating 10-12 nucleotides -TTGACA: consensus sequence, conserved between genes of diff species (also TATAAT Pribnow box, identify nucleotide at which transcription begins) -"housekeeping" sigma factor: initiate transcription of most genes transcription and RNA processing in eukaryotic cells -RNA polymerase I, II, III -primary transcript, pre-RNA: equivalent in length to full length of DNA transcribed -transcription unit: corresponding segment of DNA from primary transcript SYNTHESIS AND PROCESSING RIBOSOMAL AND TRANSFER RNAs -rDNA (DNA that encodes rRNA) found in nucleolus, help to produce ribosomes synthesizing the rRNA precursor -Oscar Miller, Jr. (1960): reveal large circular fiber in oocyte nucleoli, look like chain of Christmas trees -tandem arrangement of rRNA genes -nontranscribed spacer: region of ribosomal gene cluster not transcribed processing the rRNA precursor -pre-rRNA: single primary transcript that carve 3/4 rRNAs -lots of methylated nucleotides, pseudouridine residues -altered nucleotides part of final products, unaltered parts discarded -track synthesis with methionine, pulse-chase experiment -45S RNA in nucleolar RNA, replaced by 32S RNA, precursor to mature 28S, 5.8S rRNA, 18S rRNA go to cytoplasm -small nucleolar RNA (snoRNAs) -associate with rRNA precursor before fully transcribed synthesis and processing of the 5S rRNA -transcribed by RNA pol III, which can bind to promoter site located within transcribed portion of target gene transfer RNAs -synthesized from genes found in small clusters -transcribed by RNA pol III, promoter sequence in coding section of gene -need lots of modified bases SYNTHESIS AND PROCESSING OF MESSENGER RNAS