What do genes code for? The Central Dogma. From gene to protein DNA. protein. trait RNA. Transcription 1/9/2015. From Gene to Protein.

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1 Wht do genes code for? From ene to rotein How does code for cells & bodies? how re cells nd bodies mde from the instructions in How enes Work s cells bodies he entrl Dogm Flow of genetic informtion in cell How do we move informtion from to s? repliction gets ll the glory, but s do ll the work! nucleus From gene to cytoplsm m trnsltion rnscription from nucleic cid lnguge to nucleic cid lnguge ribose sugr N-bses urcil insted of thymine : : single strnded lots of s m, t, r, si 1

2 rnscription Mking m trnscribed strnd = templte strnd untrnscribed strnd = coding strnd sme sequence s synthesis of complementry strnd bubble enzyme polymerse build rewinding m polymerse coding strnd unwinding templte strnd Mtching bses of & Mtch bses to bses on one of the strnds polymerse Which gene is red? romoter region binding site before beginning of gene box binding site binding site for polymerse & fctors Enhncer region binding site fr upstrem of gene turns on HIH rnscription Fctors Initition complex fctors bind to promoter region suite of s which bind to turn on or off trigger the binding of polymerse to Eukryotic genes hve junk! Eukryotic genes re not continuous s = the rel gene expressed / coding s = the junk inbetween sequence eukryotic = noncoding (inbetween) sequence = coding (expressed) sequence m splicing ost-l processing eukryotic m needs work fter primry trnscript = pre-m m splicing edit out s mke mture m trnscript eukryotic primry m trnscript = noncoding (inbetween) sequence = coding (expressed) sequence mture m trnscript pre-m ~10,000 bse ~1,000 bse spliced m 2

3 Splicing must be ccurte splicing enzymes No room for mistkes! single bse dded or lost throws off the reding frme rg Ser sp Lys ly His rg Vl rg SO snrns snrns sn smll nucler Spliceosome severl snrns recognize splice site sequence cut & pste gene spliceosome No, not smurfs! snurps mture m lrit excised lterntive splicing lterntive ms produced from sme gene when is n not n different segments treted s s More post-l processing Need to protect m on its trip from nucleus to cytoplsm enzymes in cytoplsm ttck m protect the ends of the molecule dd /hylted cp dd poly- til longer til, m lsts longer: produces more m nucleus From gene to cytoplsm m trnsltion rnsltion from nucleic cid lnguge to mino cid lnguge 3

4 How does m code for s? m codes for s in triplets m 20? rg Vl sn l ys l How cn you code for 20 mino cids with only nucleotide bses (,,,)? m? rg Vl sn l ys l codon rcking the code Nirenberg & Khorn rick determined 3-letter (triplet) codon system WHYDIDHEREDBEHEFR Nirenberg (7) & Khorn (17) determined m mino cid mtch dded fbricted m to test tube of s, t & mino cids creted rtificil m found tht coded for phenyllnine he code ode for LL life! strongest support for common origin for ll life ode is redundnt severl codons for ech mino cid 3rd bse wobble Strt codon methionine Stop codons,, How re the codons mtched to mino cids? m t mino cid codon nti-codon rg Vl rnsfer structure lover lef structure nticodon on clover lef end mino cid ttched on end

5 Ribosomes Ribosomes Fcilitte coupling of t nticodon to m codon Structure ribosoml (r) & s 2 subunits lrge smll E site (minocyl-t site) holds t crrying next mino cid to be dded to chin site (peptidyl-t site) holds t crrying growing polypeptide chin E site (exit site) empty t leves from exit site E Building polypeptide Initition brings together m, subunits, inititor t Elongtion dding mino cids bsed on codon sequence ermintion end codon Leu t Leu Leu Leu m E 3 2 Vl Ser 1 l rp relese fctor n you tell the story? pre-m lrge ribosoml subunit smll ribosoml subunit /hylted cp mture m poly- til polymerse E t mino cids t minocyl t synthetse polypeptide 5