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SAY IT WITH DNA: PROTEIN SYNTHESIS WORKSHEET Category Resource type Basic Concepts of Science Dry lab Scientific Investigation Skills and Career Exploration A1.11 communicate ideas, plans, procedures, results, and conclusions orally, in writing, and/or in electronic presentations, using appropriate language and a variety of formats Prior Knowledge Students have an understanding of: The Central Dogma Basepairing in DNA vs. RNA Splicing Redundancy in the genetic code Overall Expectations Specific Expectations D2 Investigate, through laboratory activities the structures of cell components and their roles in processes that occur within the cell D2.1 use appropriate terminology related to molecular genetics D2.2 analyse a simulated strand of DNA to determine the genetic code and base pairing of DNA D3.3 explain the steps involved in the process of protein synthesis and how genetic expression is controlled in prokaryotes and eukaryotes Student Learning Goals By the end of the activity students will be to: Identify the amino acid that is coded by a given DNA sequence Identify the DNA sequence from a strand of amino acids in a polypeptide Teacher’s Notes Directions Suggestions Limitations Modifications for special need students Resource(s) This activity is to be completed after the students have learned about the central dogma, which is a fundamental and basic concept in molecular genetics. It is intended to review and solidify the concept that the genetic code provides the instructions for protein synthesis. This is an AfL activity to ensure that students understand the central dogma. In the chart below is the “DNA to amino acid dictionary.” Teachers can use this to make their own personalized messages for the students Review base pairing in DNA (A with T and G with C) vs. RNA (A with U and G with C) This activity can also be done backwards (from translation to transcription); students will learn how to determine the DNA sequences for a polypeptide/protein This activity drastically simplifies how protein synthesis occurs. o it does not accurately represent how DNA transcription occurs in eukaryotes since it leaves out mRNA processing (e.g. splicing out of introns); o It does not include other cell components (e.g. RNA polymerase, ribosomes) that are involved in DNA transcription and translation; Students should notice that methionine is found in the middle of certain DNA sequences or not at all in the questions. Students should be reminded that methionine signals for ribosomal translation. Make sure to go over the instructions as well as repeating the instructions several times Allow more time for students to complete the activity. For example, if the teacher chooses to ask the students to create their own messages, the message swop can be completed next class. This also gives students more time to ask the teacher questions one-on-one if need be. This activity was adopted and modified from: http://www.indiana.edu/~ensiweb/connections/genetics/dna.les.html DNA to Amino Acid Dictionary Letter A A A A C C D D E E F F G G G G DNA codon CGA CGC CGG CGT ACA ACG CTA CTG CTC CTT AAA AAG CCA CCC CCG CCT AA Letter Ala Ala Ala Ala Cys Cys Asp Asp Glu Glu Phe Phe Gly Gly Gly Gly H H I I I K K L L L L L L M N N DNA codon GTA GTG TAA TAG TAT TTC TTT AAC AAT GAA GAC GAG GAT TAC TTA TTG AA Letter His His His Iso Iso Lys Lys Leu Leu Leu Leu Leu Leu Met Asn Asn O P P P P Q Q R R R R R R S S S DNA codon ACT GGA GGC GGG GGT GTC GTT GCA GCC GCG GCT TCC TCT AGA AGC AGG AA Letter Pro Pro Pro Pro Glu Glu Arg Arg Arg Arg Arg Arg Ser Ser Ser S S S T T T T V V V V W Y Y Spc Spc DNA codon AGT TCA TCG TGA TGC TGG TGT CAA CAC CAG CAT ACC ATA ATG ATC ATT AA Ser Ser Ser Thr Thr Thr Thr Val Val Val Val Trp Tyr Tyr - SAY IT WITH DNA: PROTEIN SYNTHESIS WORKSHEET DNA RNA transcription Protein translation The Central Dogma states that DNA directs the synthesis of proteins by producing RNA via transcription followed by ribosomal translation of RNA into polypeptides. In this activity, you will decode sequences of DNA into "secret" messages. PART A Determine the “secret” message by transcribing and then translating the bases from the given strands of DNA below (#1-3). Use the dictionary to determine the letter that corresponds to each tRNA codon. You must record ALL your steps from transcription to translation, including the amino acids that correspond to each tRNA codon. For example: Given DNA CTT mRNA GAA tRNA CUU Letter E Amino Acid Glu If you have done this correctly, the letters should spell out a message in English. DICTIONARY tRNA AAA AAC AAG AAU ACA ACC ACG ACU AGA AGC AGG AGU AUA AUC AUG AUU AA Letter Phe F Leu L Phe F Leu L Cys C Trp W Cys C Thr O Ser S Ser S Ser S Ser S Tyr Y spc Tyr Y spc - Note: AA = Amino Acid Spc = “space” tRNA CAA CAC CAG CAU CCA CCC CCG CCU CGA CGC CGG CGU CUA CUC CUG CUU AA Letter Val V Val V Val V Val V Gly G Gly G Gly G Gly G Ala A Ala A Ala A Ala A Asp D Glu E Asp D Glu E tRNA GAA GAC GAG GAU GCA GCC GCG GCU GGA GGC GGG GGU GUA GUC GUG GUU AA Leu Leu Leu Leu Arg Arg Arg Arg Pro Pro Pro Pro His Glu His Glu Letter L L L L R R R R P P P P H Q H Q tRNA UAA UAC UAG UAU UCA UCC UCG UCU UGA UGC UGG UGU UUA UUC UUG UUU AA Letter Iso I Met M Iso I Iso I Ser S Arg R Ser S Arg R Thr T Thr T Thr T Thr T Asn N Lys K Asn N Lys K 1) DNA: TGA GTG CTT ATT ACG CTC TTA TGC TCC CGC GAG ATC CTA ACT CCC TAC mRNA: tRNA : AA: letter: DNA:CGT ATT TAA TCA ATC ACT TTG ATC TGG GTG CTC ATT TGC CTT AGGTGA mRNA: tRNA : AA: letter: 2) DNA : GGA GTG TAT GAA ATC CTA ACT ATT ACC CTC ATT GTA CGC CAG CTC mRNA: tRNA: AA: letter: DNA : ATC TGT GTG CTT ATC TGC ACC CTT TTA TGT ATG ATT AAA TAT AAG mRNA: tRNA : AA: letter: DNA : TGA GTG ATC ACTAAA AAA mRNA: tRNA : AA: letter: PART B Answer the questions below. 1) Several codons code for “spc”. Explain why this is an advantage or disadvantage for the organism. 2) Are the given strands of DNA from a eukaryotic or prokaryotic organism? Explain your answer. 3) Explain where translation would begin for: a. DNA sequence #1 (same as above): TGA GTG CTT ATT ACG CTC TTA TGC TCC CGC GAG ATC CTA ACT CCC TAC CGT ATT TAA TCA ATC ACT TTG ATC TGG GTG CTC ATT TGC CTT AGGTGA b. DNA sequence #2 (same as above): GGA GTG TAT GAA ATC CTA ACT ATT ACC CTC ATT GTA CGC CAG CTC ATC TGT GTG CTT ATC TGC ACC CTT TTA TGT ATG ATT AAA TAT AAG TGA GTG ATC ACTAAA AAA 4) Construct your own secret DNA message by working backwards in the space provided below (from English AA tRNA mRNA DNA). This message will be handed in on a separate piece of paper with ONLY the DNA sequence on it and then it will be randomly given out to one of your classmates to decode. Keep in mind that the letters B, J, U, X, and Z cannot be used in your message. (CAUTION: obscene or derogatory messages are not acceptable). ANSWERS 1) DNA:TGA GTG CTT ATT ACG CTC TTA TGC TCC CGC GAG ATC CTA ACT CCC TAC mRNA: ACUCAC GAA UAA UGC GAGAAU ACG AGG GCG CUC UAGGAU UGA GGG AUG tRNA : UGA GUGCUU AUU ACG CUC UUAUGC UCC CGC GAG AUC CUA ACU CCC UAC AA: Thr His Glu spc Cys Glu Asn Thr Arg Ala Leu spc Asp Thr Gly Met letter: T H E C E N T R A L D O G M DNA:CGT ATT TAA TCA ATC ACT TTG ATC TGG GTG mRNA: GCA UAAAUU AGU UAG UGA AACUAG ACC CAC tRNA : CGU AUU UAA UCA AUC ACU UUGAUC UGG GUG AA: Ala spc Iso Ser spc Thr Asn spc Thr His letter: A I S O N T H CTC ATT TGC CTT AGGTGA GAGUAA ACG GAA UCC ACU CUC AUUUGC CUU AGGUGA Glu spc Thr Glu Ser Thr E T E S T 2) DNA : GGA GTG TAT GAA ATC CTA ACT ATT ACC CTC ATT GTA CGC CAG CTC mRNA: CCU CAC AUA CUU UAG GAU UGAUAA UGG GAG UAACAU GCG GUC GAG tRNA: GGA GUGUAU GAA AUC CUA ACU AUU ACC CUC AUU GUA CGC CAG CUC AA: Pro His Iso Leu spc Asp Thr spc Trp Glu spc His Ala Val Glu letter: P H I L D O W E H A V E DNA : mRNA: tRNA : AA: letter: ATC TGT GTG CTT ATC TGC ACC CTT TTA TGT ATG ATT AAA TAT AAG UAGACA CAC GAA UAG ACG UGG GAA AAU ACA UAC UAA UUU AUA UUC AUCUGU GUG CUU AUC UGC ACC CUU UUA UGU AUGAUU AAA UAU AAG spc Thr His Glu spc Thr Trp Glu Asn Thr Tyr spc Phe Iso Phe T H E T W E N T Y F I F DNA : TGA GTG ATC ACTAAA AAA mRNA: ACU CAC UAG UGA UUUUUU tRNA : UGA GUGAUC ACU AAA AAA AA: Thr His spc Thr Phe Phe letter: T H O F F PART B Answer the questions below. 1) Several codons code for “spc”. Explain why this is an advantage or disadvantage for the organism. A change in a single base may not necessarily result in a change in amino acid. Therefore, it would be an advantage for the organism to have multiple codons for “spc”. This is an example of redundancy. 2) Are the given strands of DNA from a eukaryotic or prokaryotic organism? Explain your answer. The strands of DNA are from a prokaryotic organism because splicing was not required. 3) Explain where translation would begin for: a. DNA sequence #1 (same as above): TGA GTG CTT ATT ACG CTC TTA TGC TCC CGC GAG ATC CTA ACT CCC TAC CGT ATT TAA TCA ATC ACT TTG ATC TGG GTG CTC ATT TGC CTT AGGTGA Translation would begin at TAC, which is underlined above. Translation begins here because TAC codes for methionine, which signals the initiation of translation for the ribosome. b. DNA sequence #2 (same as above): GGA GTG TAT GAA ATC CTA ACT ATT ACC CTC ATT GTA CGC CAG CTC ATC TGT GTG CTT ATC TGC ACC CTT TTA TGT ATG ATT AAA TAT AAG TGA GTG ATC ACTAAA AAA This sequence would not be translated since it lacks methionine (Met )to signal the initiation of translation for the ribosome. 4) Construct your own secret DNA message by working backwards below (from English AA tRNA mRNA DNA). This message will be handed in on a separate piece of paper with ONLY the DNA sequence on it and then it will be randomly given out to one of your classmates to decode. Keep in mind that the letters B, J, U, X, and Z cannot be used in your message. (CAUTION: obscene or derogatory messages are not acceptable). All students will have a different message.