Problem Set 4 on Central Dogma

ChemicalBiology03 Fall2009 Goutte

Problem Set 4 on Central Dogma

(dueMondayOct.19th,inclassorby5:00pminProf.Goutte'soffice)

1. DefinethefollowingtermsastheyareusedinregularEnglishlanguageANDgivethespecial meaningeachtermhaswhenappliedtothelivingcell.

a. Replication b. transcription c. translation d. splicing

2. Nowforsomenumbers...

a. HowmanydifferenttypesofnucleotidesarefoundinRNA? b. Howmanydifferenttypesofaminoacidsarefoundinproteins? c. Howmanynucleotidesareneededtocodeforasingleaminoacid? d. Howmanydifferentcodonsarethereinthegeneticcode? e. Howmanycodonscodeforaminoacids? 3. Myoglobinis153aminoacidslong. a. Whatwouldbetheminimumnumberofnucleotidesrequiredtoencodemyoglobin? b. WhymightthesizeofthemyoglobinprimaryRNAtranscriptbelargerthanyouranswer

above?

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4. Usethegeneticcodetoidentifywhichofthefollowingnucleotidesequenceswouldcodefor thepolypeptidesequencearginine-glycine-aspartate:

a. 5'-AGAGGAGAU-3' b. 5'-ACACCCACU-3' c. 5'-GGGAAAUUU-3' d. 5'-CGGGGUGAC-3'

5. Explainwhyifyouaregivenaproteinsequence,youcannotpredicttheexactRNAsequence thatwasusedbythecelltogeneratethatsequence. 6. Considerthehypotheticalproteinrepresentedbysingleletteraminoaciddesignations: A-M-H-E-R-S-T. a. ProposeoneRNAsequencethatcouldencodethissequence(don'tworryaboutstart codonsforthisexercise).

b. CanyoufigureoutmathematicallyhowmanydifferentRNAsequencescouldcodefor thisminiprotein?

7. Hereisthebeginningofaprotein-encodinggenesequence.

5'-ATGAAGTTTGGCACTTAA-3' 3'-TACTTCAAACCGTGAATT-5'

a. GivetheRNAtranscriptthatwouldbetranscribedoffofthebottomstrand: b. TranslatethisRNAsequenceintoaproteinsequence. c. GivetheRNAtranscriptthatwouldbetranscribedoffofthetopstrand: d. TranslatethisRNAsequenceintoaproteinsequence.

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#7continued e. Let'sassumethatthebottomstrandisthestrandthatisusedasatemplatestrand whenthisgenegetstranscribed.Whatwouldbetheeffectonthefinalprotein productifamutationcausedthefollowingsinglebase-pairinsertion:

5'-ATGAAGATTTGGCACTTAA-3' 3'-TACTTCTAAACCGTGAATT-5'

f. Whatwouldbetheeffectonthefinalproteinproductifamutationcausedthe followingsinglebase-pairsubstitution:

5'-ATGAAGTTCGGCACTTAA-3' 3'-TACTTCAAGCCGTGAATT-5'

g. Whatwouldbetheeffectonthefinalproteinproductifamutationcausedthe followingsinglebase-pairsubstitution:

5'-ATGAAGTTTCGCACTTAA-3' 3'-TACTTCAAAGCGTGAATT-5'

h. Whatwouldbetheeffectonthefinalproteinproductifamutationcausedthe followingsinglebase-pairsubstitution:

5'-ATGTAGTTTGGCACTTAA-3' 3'-TACATCAAACCGTGAATT-5'

i. Whichoftheabovemutation(s)wouldyouexpecttobethemostsevereintermsof theoveralleffectonthepersoncarryingsuchamutation?Explain.

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