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.
Review base pairing in DNA (A with T and G with C) vs. RNA (A with U and G with C)
Ask the students to create their own secret message (PART B #4). The students can trade
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
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 : CTA TTA CGA ATC TAG AGC ATT GAA TAG AAA CTT
mRNA:
tRNA:
AA:
letter:
2) DNA : TAC ATA ATC TAC TAG TTA CTA ATC TAT AGA ATT TAC CGA CCC TTG TAT
mRNA:
tRNA :
AA:
letter:
DNA : AAA TAG ACG CTT TTA TGC
mRNA:
tRNA :
AA:
letter:
3) 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:
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: CTA TTA CGA ATC TAG AGC ATT GAA TAG AAA CTT
b. DNA sequence #3: 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
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 : CTA TTA CGA ATC TAG AGC ATT GAA TAG AAA CTT
mRNA: GAU AAU GCU UAG AUC TCG UAA CUU AUC UUU GAA
tRNA: CUA UUA CGA AUC UAG AGC AUUGAA UAG AAA CUU
AA: Asp Asn Ala spc Iso Ser spc Leu Iso Phe Glu
letter: D N A
I
S
L
I
F
E
2) DNA : TAC ATA ATC TAC TAG TTA CTA ATC TAT AGA ATT TAC CGA CCC TTG TAT
mRNA: AUG UAU UAG AUGAUC AAU GAU UAG AUAUCU UAA AUG GCU GGG AAC AUA
tRNA : UAC AUA AUC UACUAG UUA CUA AUC UAUAGA AUU UAC CGA CCC UUG UAU
AA: Met Tyr spc Met Iso Asn Asp spc Iso Ser spc Met Ala Gly Asn Iso
letter: M Y
M I
N D
I
S
M A G
N I
DNA : AAA TAG ACG CTT TTA TGC
mRNA: UUU AUC UGC GAA AAU ACG
tRNA : AAA UAGACG CUU UUA UGC
AA: Phe Iso Cys Glu Asn Thr
letter: F
I
C
E
N T
3) 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 AUU UGC CUUAGGUGA
Glu spc Thr Glu Ser Thr
E
T E
S T
PART B
Answer the questions below.
5) 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.
6) 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.
7) Explain where translation would begin for:
a. DNA sequence #1: CTA TTA CGA ATC TAG AGC ATT GAA TAG AAA CTT
This sequence would not be translated since it lacks methionine (Met)to signal the initiation of
translation for the ribosome.
b. DNA sequence #3: 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.
8) 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.
ADDITIONAL DNA MESSAGES with ANSWERS KEY
1. CCT CTT TGC ACT CGG ATC GTA CGC TAT TCT ATG ATT ACA CGG TTG CGA TCC ATA ATC
Get a hairy canary (A. Mulder)
2. AGA TAC TAG GAC CTT ACT CGA TTG CTG ATT GCG CGA CTA TAA CGG TGC CTC ACT CGG ATT AAC
TAG
TGC TGA AAT CTT ATT ACG GTA CTT CTC GCC ATC
Smile and radiate a little cheer (A. Mulder)
3. TCC CTT GGG GAA TAT ACA CGC TGG CTT ACT CGA ATT TGA CTC CGT ACG GTA CTC GCC ATC
Replicate a teacher (J. Shepherd)
4. AGA ACA TAA CTC TTA ACA CTC TAA AGA CCA GCA CTC CGA TGA
Science is Great (H. Bazan)
5. TAA ACT CGG TAC ATT CTA GCT TAG CAC TAA TTA CCC ATC
I am driving (T. Nguyen)
6. TAC CGT TTC CTT ATT GAT CGC GCC CCA CTC ATT CTT CGG TCT AGG ATC
Make large ears (J.G. Oliva)
7. CTA GCC CTC CGT TAC TAG TTA CCT ACT TAT TCA ATT TTG TAA ACG CTC ATC CGA ACC CGC TTT TAA
TTG CCC ACT TAG TCG ATT ACC CGT TTA TGT TAA TTA CCT ATC
Dreaming is nice. Awaking is wanting (K. Vo)
8. ACC GTG ATA ACT CGT GCT CTT ATT ACC CTC ACT AAT CTC CGG TCC TTA TAT TTG CCT ATT TGC GTA
TAG TCG ATC
Why are we learning this (J. Mi1i)
9. TAC CGA TTT CTT ACT AGT GGC TCC TAT TTA CCT ATA ATT ACA GTG TAA ACG TTC CTC TTA TCA ATC
Make springy chickens(D. D. Ho)
10. CTA TTA CGA ACT TAG AGC ATT GAA TAG AAA CTT ATC
DNA is life (P. Labrador)
11. CTC CAC GTG AGA ATT CAC CGA GCA TCA TAG TGG ATG ATT AGA ACC TAT TAC TAC TAT TTG CCT
ATC
EVHS Varsity Swimming (A. Valdez-Lanam)
12. ACC GTG ATA ACT CGA GCA CTC ATT GGC AAC CGC TTA TGT AGC ATT CCT TCT CTC CTT TTG ATC
Why are plants green (A. Valdez-Lanam)
13. ACG GCT CTC CGT TGT CTC ACT CGA TTG ATT CTC ATG CTT ATC
Create an eye (C. Smith)
14. CTG CTT AGT TAT CCA TTG ACT CGA ATT GTG CGC TTG CTG ATC
Design a hand (D. Smith)
15. ACA GCC CTT CGC TGC CTC ACT CGA ATT AAA TAT TTG CCA CTC GCT ATC
Create a finger (C. Smith)
16. AAA TAT TTA CTA ACT TGG GTA CTT ATT AGC CTC ACG GCG CTT TGT ATT TAC CTC AGA AGC CGA
CCA
CTC ATC
Find the secret message (J. Thailer)
17. CTT CGA TGA ATT CCA GCC CTC CTT TTG ATC CTT CCA CCT AGC ATC CGA TTG CTA ACT GTA CGC
TAM
Eat green eggs and ham (H. Thompson)
18. AGT TAC TAA GAA CTT ACT TAG TGT TCA ATC GTA CTT CGA GAG TGG GTA ATG
Smile it's healthy (H. Thompson)
19. ACC CGA TGG CTC TCT ATC TAT AGC ATT ACA AAC CTC CGA GCG
Water is clear (J Blaskey)
20. ACG CTT GAA AAT AGG ACT CGA TCT CTC ATC CCG TCC CTG CGC TGC ATT TGT GTA TAG TTA CCC
AGG
Cells are great things (A. Skinner)
21. GAA CTC CGA TCT TTG TAT CCG ACT CTA TTA CGG ATC TAA AGC ATT CCT TCC CTT CGT TGT
Learning DNA is great (A. Skinner)
22. TAC ATA ACT TAC TAG TTA CTA ATC TAT AGA ATT TAC CGA CCC TTG TAT AAA TAG ACG CTT TTA
TGC
ATC
My mind is magnificent
23. TAA ACT GTG CGA CAC CTC ATT CGT ATC CTA GCG CTT CGT TAC ATC
I have a dream
24. AGA CGG CAA CTC ATT TGG GTG CTT ACT TGT TCT CTT CTC AGT ATC
Save the trees
25. CCG GCA CTC CTT CTA ATT GCT CTT TAG CCA TTA AGT ACT TAA TTG ATC ACC CGA AAT GAG ATT
AGG
TGT TCC CTC CTT TGC ATC
Greed reigns in Wall Street
26. GAT TAA AAA CTC ACT TAG AGC ATT AGT GGG CTT ACA TAA CGG GAA ATC
Life is special
27. ACC GTA ATG ATT TAG AGG ATC CTG TTA CGA ACT TTG CTC ACA CTT AGC AGT CGG TCC ATA ATC
Why is DNA necessary
28. GTA CGA GGA GGA ATG ATC CAA CGA AAC CTC TTA TGA TAA TTA CTC AGG ATC CTA CGA ATA ATC
Happy Valentines Day
29. AAT CTC CGA GCT TTG TAG TTA CCC ATT TAG AGT ATC TAG TTG TGT CTC GCT CTC AGG TGC TAT
TTG
CCT ACT
Learning is interesting
30. CGA ACT AGA TAA CCC TTA TAG AAA TAT ACA CGC TTG TGA AAC ATA ATC CGG CTG CAA CGT TTA
ACA
CTC CTA ATT AGG ACA TAA CTC TTG ACA CTT ACT TAG AGA ACT CTC CGC TCA TAG GAG ATA ATT
TAC TAA AGA TGA CGG TTT CTT TTG ACT CGA AGC ATT TAC CGC CCC TAG ATC
A significantly advanced science is easily mistaken as magic