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SAY IT WITH DNA: PROTEIN SYNTHESIS WORKSHEET
DNA
RNA
transcription
polypeptide
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. This process is unidirectional.
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:
Write sentence 1) here:
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:
Write sentence 2) here:
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:
Write sentence 3) here:
PART B
A mutation is a random error or mistake in DNA. Transcribe and translate DNA strand 1 again, this time
with its mutation.
1) DNA : CTA TTA CGA ATC TAG AGC ATT GAA TAG ACA CTT
mRNA:
tRNA:
AA:
letter:
Write the mutated sentence here:
1. At what part of the message did the mutation occur?
2. How does the mutated sentence compare to the original message?
3. Did the mutation change the meaning of the meaning? How?
4. Explain how a mutation may not affect the meaning of a polypeptide?
PART C
1) 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 as they don’t
have an equivalent nucleotide sequence. (CAUTION: obscene or derogatory messages are not
acceptable).
Example:
Letter E
Amino Acid
Glu
tRNA
CUU
mRNA
GAA
Amino Acid
DNA
CTT