Download Protein Synthesis and Words - Hewlett

Name:
Date:
Lab:
Protein Synthesis and Words
Adapted from a lab by Lynn Marie Wartski
Objective: Follow the steps of protein synthesis, Understand how genes are expressed.
Background:
DNA carries and stores the information for the synthesis of all of the proteins of
an organism. We commonly call this our “traits”. Protein molecules are large and
complex, composed of hundreds of amino acid units. In each kind of protein, the amino
acid units are linked together in a definite and specific sequence. The sequence of amino
acids in a protein molecule is determined by the sequence of the nucleotides in the DNA
of the organism. All of the different proteins that occur in organisms are composed of
only twenty varieties of amino acids.
In the first step leading to protein synthesis, the nucleotide sequence of the DNA
is transcribed (the process is called transcription) into a long single-stranded molecule of
RNA, termed messenger RNA (mRNA). The mRNA moves out of the nucleus and into
the cytoplasm through small pores in the nuclear membrane.
In the cytoplasm, ribosomes temporarily attach to the mRNA. Triplet (occurring
in groups of threes) sequences of nucleotides, called codons, in the mRNA form a sort of
pattern, or code, that specifies the order in which the amino acids of a protein are to be
linked. While a ribosome is attached at each codon along the mRNA, molecules of
another kind of RNA, transfer RNA (tRNA), bring amino acids into place, each
according to the code or sequence in the mRNA. As the ribosomes move along the
mRNA from codon to codon, the appropriate amino acids are brought into place and
linked together according to the sequence of codons. Thus, the code in the mRNA is
translated into a special sequence of amino acids. The order of the amino acids in the
protein, therefore, is specified by the mRNA, which in turn is transcribed from the DNA.
Materials:


DNA Template Cards: these will be kept on the teacher lab table at all times.
After all, DNA must not leave the nucleus.
Codon chart for sentences
Procedure:
1.
2.
3.
4.
5.
6.
7.
8.
Your group will be assigned a number
Go to the table, with the DNA template cards
Find the card with your number
While staying in the nucleus (the table with the cards), transcribe the mRNA,
from your DNA card, onto your lab report.
Return to your table.
Using the codon chart, translate your protein from the mRNA
Get another number from your teacher to make another protein.
Ask Mr. Parris for an actual gene sequence to use and attempt to translate it using
the real amino acid sequences the ribosome would be producing.
Results:
Gene number: _____________
mRNA:_________________________________________________________________
________________________________________________________________________
Protein:_________________________________________________________________
_______________________________________________________________________
Gene number: _____________
mRNA:_________________________________________________________________
________________________________________________________________________
Protein:_________________________________________________________________
_______________________________________________________________________
Gene number: _____________
mRNA:_________________________________________________________________
________________________________________________________________________
Protein:_________________________________________________________________
_______________________________________________________________________
Conclusion:
1. Why is the making of mRNA called transcription and not replication?
2. Why is the making of protein called translation?
3. Identify the organelles where transcription and translation occur.
4. Write the order of nucleotides in mRNA that would be transcribed from the
following strand of DNA:
G T A T A C C A G T C A T T T G T C
Then, list in order, the amino acids coded by this sequence
mRNA_________________________________________________________________
amino acids______________________________________________________________
5. Sometimes a mistake occurs in the translation of an mRNA strand. Suppose that
the reading of the mRNA strand in question 4 began, by mistake, at the second
nucleotide instead of the first. The first codon would be AUA. Write the sequence
of amino acids that would be formed now.
________________________________________________________________________
6. Suppose the bases of the DNA strand in question 4 were not transcribed correctly
and the mRNA read:
C A C A U G G U U A G U A A G C A G
How many mistakes were made in transcription? Write the abbreviations for the
amino acids that would be formed by translation of the mRNA
________________________________________________________________________
Codon Chart for Sentences
FIRST
BASE
U
SECOND
BASE
C
A
AUU
an
dog
A
AUC
band
have
A
AUA
rock
A
G
G
G
G
C
C
C
C
U
U
U
U
AUG
start
GUU
nothing
GUC
dress
GUA
a
GUG
brother
CUU
music
CUC
love
CUA
I
CUG
roll
UUU
life
UUC
code
UUA
DNA
UUG
for
ACU
ACC
ACA
breath
ACG
funny
GCU
education
GCC
much
GCA
so
GCG
fun
CCU
subject
CCC
biology
CCA
when
CCG
is
UCU
informed
UCC
must
UCA
together
UCG
be
THIRD
BASE
A
G
AAU
dresses
AGU
Offspring
AAC
mother
best
AGC
AAA
your
AAG
wears
GAU
and
GAC
demented
GAA
all
GAG
puppies
CAU
pulled
CAC
rubber
CAA
old
CAG
breaks
UAU
this
UAC
in
UAA
we
UAG
Stop.
U
C
AGA
the
A
AGG
are
GGU
father
GGC
to
GGA
door
GGG
future
CGU
day
CGC
water
CGA
drink
CGG
every
UGU
little
UGC
you
UGA
around
UGG
read
G
U
C
A
G
U
C
A
G
U
C
A
G
DNA Cards
1. TAC,TTT,TTG,TTC,CAT,GTG,TAG,ATC
2. TAC,TTT,TTG,TTA,ACG,TGC,ATC
3. TAC,ATT,TGG,TGA,TGT,ATC
4. TAC,TCT,TCA,TCC,TCT,TCG,TAT,TAG,ATC
5. TAC,TAA,GTT,GTG,TAG,GTC,GGT,GTA,ATC
6. TAC,GGG,GGC,TCT,TCG,GGA,ATC
7. TAC,GCT,GCG,GCC,GCA,ATC
8. TAC,GAT,GAG,TAT,CTA,GAC,GAA,ATC
9. TAC,ATT,TCC,CTT,CTG,CTC,ATC
10. TAC,GGG,GGC,CGT,CGG,CGC,ATC
11. TAC,CGA,GGC,TCT,CCT,CCG,TCT,CCC,ATC
12. TAC,TTT,CCA,TTC,CAT,CAG,ATC
13. TAC,TTT,CAC,TTC,CAA,ATC
14. TAC,ATT,TCC,CTT,ATG,ATA,AGT,ATC
15. TAC,ATT,AGG,AGC,AGA,GCC,GCA,ATC
16. TAC,TAT,CTA,GAC,GAA,GGC,TCT,TCG,ATC
17. TAC,GGG,GGC,CTT,ACT,ACG,ATC
18. TAC,ACC,CAT,ACA,GCC,GCA,ATC
19. TAC,ATT,GGC,TCT,AAG,AAC,AAA,ATC
20. TAC,AAT,AGG,AGC,ACC,AAC,AAA,ATC
21. TAC,TAC,CCC,CTC,TAC,TCC,TCA,GGG
22. TAC,TCC,TTA,GTC,GTC,ACT,TTG,TTT
23. TAC,CCC,TTG,TAT,TCA,GGG,TGG,CCG
24. TAC,TAC,CTC,ATG,TTT,TGG,ATG,AGG,CAT
25. TAC,ATT,CAT,ACC,GTA,ATT,ATC,TCT,CAG
26. TAC,TTG,TCT,GTT,CCT,AAA,GAT,CAC,TGA
27. TAC,TGC,AGA,CAT,CGC,ATA,TAC,AGG,TCC
28. TAC,AGG,TCC,AAA,GGT,AGA,GGA,AGA,AGA
29. TAC,ATA,CCT,AGA,CTG,AAA,TAC,GAA,CTT
30. TAC,CTA,GAC,TGA,AAT,ACG,AAA,CTT,CAA