Download Name Hour ______ Score

HW #3 Protein Synthesis
due Wednesday December 8th
Name ______________________________________ Hour ______
Due: ____________
Lab
Cystic
Fibrosis
Data Table
____
Questions
____
Lab
Role
Data Table
____
Modeling
Questions
____
Your Points
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5 possible
1
Protein Synthesis Role Modeling Activity
Cooperative Learning Activity:
Student will learn the process OF protein synthesis. To do so, each student will play a role in
the process of protein synthesis. Students will work in groups of three to model how
information in DNA is expressed as protein.
Roles:
 1 student will be mRNA (transcribing the code of DNA to bring outside of nucleus to the
ribosome)
 1 student will be tRNA and translate the codons at the ribosome
 1 student will be taking anticodon from ribosome to look for the correct amino acid (in this
case a word) and bring it back to the ribosome to complete a sentence)
Procedure:
1. The teacher will be at the “nucleus desk” which is where the DNA templates are located.
DNA templates cannot leave this area.
2. The student who is responsible for mRNA should come into the nucleus and pick up the DNA
template card number and transcribe it AT THE NUCLEUS desk, into mRNA (remember to
use uracil). This student (mRNA) will take the transcribed sequence to the ribosome
student’s desk where it will be translated by tRNA.
3. Once the mRNA brings the transcribed code to the ribosome the tRNA will translate or
WRITE OUT the tRNA anticodon sequence.
4. Then the Amino acid student will search out the correct anticodon card located around the
room (cytoplasm) and flip the card over revealing the word. S/he will write down the
word.
5. Once the Amino Acid Student has deciphered all the codes and completes the sentence, a
student in the group will tell the teacher their group sentence. If it is correct, then they
can move on to the next DNA template. HINT: After completing the sentence, read the
sentence. If it does not make sense, it is not correct, a mutation has occurred. Review the
DNA template card to see where the mutation took place.
2
Write the DNA template # you are transcribing and then complete the translated
sentences in the spaces below:
DNA Template #
mRNA transcription:
tRNA:
AA Sentence:
__________________________________________________________________
DNA Template #
mRNA transcription:
tRNA:
AA Sentence:
____________________________________________________________________
DNA Template #
mRNA transcription:
tRNA:
AA Sentence:
__________________________________________________________________
3
Analysis:
1. List three differences between DNA and RNA.
DNA
RNA
 Bases (A,T,G,C)
(A,U,C,G)
 Sugar (deoxyribose)
(ribose)
 # of Strands (2)
1
 Where found (nucleus)
nucleus and cytoplasm
2. You discover a new coding strand of DNA and determine it has 18 -nucleotides, how many amino
acids will be in the polypeptide that is formed? 6
A. How many nucleotides will be in the mRNA? 18
B. How many anticodons will there be? 6
3. What is the function of mRNA?

Transcribe DNA code and bring it to the ribosomes
4. What are the difference between messenger RNA and transfer RNA? How are they similar?
Similarities
Differences
Shape
phosphate/sugar/nitrogen bases
5. What is transcription? Describe the process.

Transcription is the process of copying DNA code into mRNA
o
o
o
Initiation = DNA helix unwinds at gene
Elongation = RNA polymerase adds complementary ribonucleotides to DNA gene
strand
Termination = Polymerase reaches termination site; DNA helix reforms
6. Define translation. Describe the process.

Translation is the process of synthesizing proteins from information carried by mRNA
o mRNA attaches to ribosome in cytoplasm
o Ribosome looks for start codon
o tRNA with correct anticodon brings amino acid to mRNA
o Second tRNA with correct anticodon brings amino acid to next mRNA codon
o Amino acids form a peptide bond
o Process continues until ribosome reaches a stop codon (UAA,UAG,UGA)
7. Do all of your sentences that you have up above make sense?

Answers will vary
8.
If one or more of your sentences do not make sense, can you explain what might have
happened to cause the mistake to occur? What is it called when a mistake occurs while making
a protein?

A mistake is called a mutation
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9. For each sentence that you have that does not make sense, can you locate the error? Check
the answers on the board in the front of the room. Did you have any sentences that made
sense but are not the same sentences on the board? Answers will vary.
10. Explain how the same protein can be made even though there is an error located on the DNA
strand itself? Some codons code for the same amino acids
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Lab Genetic Testing for Cystic Fibrosis
1. Carefully transcribe the DNA base sequence for each individual on the worksheet. Check
your work by comparing your worksheets with your lab partner.
2. Now translate the DNA code into amino acids, if there are two different amino acids
record them in the circle like this: A/V. Know then that two different versions of the
protein may be made.
Josina
1
2
3
4
5
6
7
8
9
1
1
1
1
1
1
1
1
1
1
2
2
2
2
2
DNA
DNA
“Ma”
“Pa”
T
A
C
T
C
C
T
T
T
G
T
C
T
T
C
G
G
T
G
T
T
A
A
G
T
A
C
T
C
C
T
T
T
G
T
C
T
T
C
G
G
T
G
T
T
A
A
G
Leah
Amino
Acid
M
R
K
Q
K
P
Q
F
DNA
DNA
“Ma”
“Pa”
T
A
C
T
C
C
T
T
T
G
T
C
T
T
C
G
G
T
G
T
T
A
A
G
T
A
C
T
C
C
T
T
T
G
T
C
T
T
C
G
G
T
G
T
T
A
A
G
Martin
Amino
Acid
M
R
K
Q
K
P
Q
F
DNA
DNA
“Ma”
“Pa”
T
A
C
T
C
C
T
T
T
G
T
T
T
T
T
G
G
T
G
T
T
A
A
G
T
A
C
T
C
C
T
T
T
G
T
T
T
T
G
G
G
T
G
T
T
A
A
G
Richard
Amino
Acid
M
R
K
Q/Q
K/N
P
Q
DNA
DNA
“Ma”
“Pa”
T
A
C
T
C
C
T
T
T
G
T
C
G
G
T
G
G
T
G
T
T
T
A
C
T
C
C
T
T
T
G
T
T
G
G
T
G
G
T
G
T
T
Amino
Acid
M
R
K
Q/Q
P
P/Q
V/F
F
3. Examine the DNA base sequences of all four individuals and circle any differences. Do
any of the individuals have the same sequence in both the “maternal” and “paternal”
chromosome? If so, name the individual. Is this person homozygous or heterozygous?
Josina & Leah (homozygous)
4. Examine Richard's base sequences. What is different about his DNA? Propose a
hypothesis to explain your observations. Missing 3 nucleotides in both genes.
Therefore lysine is not used and proper protein is not made.
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5.
Does a difference in DNA base sequence always mean a difference in the amino acid?
Explain your answer with an example from the data table. No. An amino acid may be
coded for by several codons. In Martin’s 10, 11, 12 nucleotides, there are 2
different codons, but the same amino acid is coded for.
6.
If the difference in base sequence is drastically different, compare the sequence to
Josina's DNA. Josina is homozygous normal. Remember, CF is homozygous recessive.
Therefore, if one chromosome has a sequence exactly the same as Josina's, the
individual is heterozygous and does not have C, but does carry the CF gene. A carrier for
CF can make one half of their protein that is functional and will not have CF. Classify
each person as heterozygous, homozygous dominant or homozygous recessive.
Josina- homozygous normal
Leah - homozygous dominant
Richard – homozygous recessive
Martin – heterozygous dominant
7.
How does Martin’s amino acid sequence differ from Josina's? Do you think Martin has
CF? Why or why not? Martin’s gene from Pa is different than Josina’s genes forming
a different amino acid sequence. Martin does not have CF because he has a
dominant gene from Ma.
8.
Compare the amino acid sequence of Richard with Josina's. What is the defect in
Richard's amino acid sequence? What causes this difference? Richard’s amino acid
sequence is shortened. He has 2 recessive gens that have deletions of 3 nucleotides
(one codon) so that there is one amino acid missing from the protein.
9.
If you wanted to determine if an individual has cystic fibrosis would you use a karyotype
or a DNA sequence? You would need to take a look at the DNA sequence.
10.
If Josina and Richard have children what is the chance they would have a child with CF
(think Punnett Square, seven steps)? If Josina and Richard have children, none of
their children will have CF, but all will be carriers of the recessive gene.
11. If Josina and Martin marry what is the chance they would have children without CF?
Also, what is the chance they would have children who were carriers? If Josina and
Martin have children, their children will not have CF, but there is a 2/4 chance
(50%) that their children will be carriers of the recessive gene.
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