Download Protein Synthesis Mutation WebQuest

 Go to this link: http://molo.concord.org/database/activities/102.html
o It is called: MUTATIONS: CHANGING THE GENETIC CODE (A 7-PAGE
ACTIVITY)
 Click the link to go to the activity. Be sure to only click it ONCE.
 The next screen you will see says “How Mutations Work” underneath a
diagram of the double helix
 Follow the instructions below for each mutation model.
1. Introducing Mutations
a. What is a mutation? _____________________________________
b. What causes mutations? __________________________________
c. 3 types of mutations: ______________, ______________,
_________________
2. About the Protein Synthesis Model
a. According to the key, what are the DNA nucleotide bases? ________
RNA bases? ________
b. According to the key, what color will the amino acids be if they are
NOT attracted to water? _____
c. According to the key, what color will the amino acids be if they ARE
attracted to water? ______
d. CLICK “TRANSCRIBE DNA TO mRNA" then answer these questions:
-A group of three nucleotides codes for one amino acid and is called
a CODON. Notice the black tick marks above the DNA strand showing
these triplet groups. How many amino acids are coded for by the
strand in the model? _______
-In this model, the bottom DNA strand is transcribed. Which DNA
strand is most similar to the RNA strand? __________
e. CLICK “TRANSLATE mRNA to PROTEIN” then answer the question
below: One amino acid in the protein is different from the others. Is
it hydrophobic or hydrophilic? __________
3. Substitution Mutations:
Challenge: Make a mutation that causes a property change. You will
make a mutation that replaces a hydrophobic amino acid with a
hydrophilic one.
a. Synthesize a normal (un-mutated) protein: Press the transcribe
button. Then, press the translate button. Pause the model ( )
immediately after the last amino acid is made
b. Find the second amino acid in the chain. It's labeled "Phe", meaning
it is a phenylalanine. It's pink, meaning it's hydrophobic. This is the
amino acid you will replace by making a mutation.
c. Press the “take a snapshot” button and type “normal, un-mutated
protein” in the box.
d. Press reset ( ).
e. The 2nd DNA triplet codes for the phenylalanine. Find the second
nucleotide on the top strand (it's the fifth nucleotide, a T).
f. Right click on this nucleotide, and select a substitution mutation to
change the T to C.
g. Synthesize your mutant protein: Press the transcribe button. Then,
press the translate button. Pause the model ( ) immediately after
the last amino acid is made.
h. The second amino acid is now _____ and is (circle one-HYDROPHOBIC
or HYDROPHILIC).
i. Press the “take a snapshot” button and type “substitution mutation”
in the box.
j. Press reset ( ) to get back the original DNA sequence.
k. Some substitution mutations result in a malfunctioning protein, but
others do not. Why is this? (write answer below and in the box on
the screen)
4. Silent Mutations
a. Synthesize a normal (un-mutated) protein: Press the transcribe
button. Then, press the translate button. Pause the model ( )
immediately after the last amino acid is made
b. The letters on the amino acids indicate which amino acid they are.
Notice that there are 3 Leu's. These are 3 leucine amino acids.
c. Each of the leucines is coded in this case by a different triplet in the
DNA. These triplets are like synonyms- three different words that all
mean the same thing. To learn these three triplets, first find the
position of each on the chain. Count, starting at the blue one.
d. Look at the DNA triplet that codes each of the three leucines. Now
you know three triplets that all code for Leucine. Write them here
_______, _______, ________
e. Make a substitution that replaces one nucleotide with another but
keeps the amino acid the same. You will want to change one of the
leucine triplets into another.
f. Synthesize your new protein with its silent mutation, to verify that
there is still a leucine where you created your mutation. IF THERE IS
NOT A LEUCINE IN THE SPOT YOU MADE THE MUTATION, TRY AGAIN
BY PRESSING THE RESET BUTTON. START OVER IN THE DIRECTIONS
AT LETTER “e.”
g. Press the “take a snapshot” button and type “silent mutation” in the
box
h. How did you create the silent mutation? (explain, giving the code for
the triplet where you made your substitution, before AND after the
mutation.) (write answer below and in the box on the screen)
5. Stop Codon
a. Pick a stop codon from the list next to the model.
List the stop codons here: ______, _______, _______
b. Choose a triplet somewhere in the middle of the DNA strand and
make substitutions to the triplet to fit the stop codon nucleotides
(use the right click button).
c. Make three substitution mutations to the top strand to create the
stop codon. Where the stop codon has a U, use a T.
d. Synthesize your mutant protein: Press the transcribe button. Then,
press the translate button. Pause the model ( ) immediately after
the last amino acid is made.
e. Press the “take a snapshot” button and type “stop codon insertion”
f. Why do mutations that create a stop codon have a bigger effect on
the protein than other mutations? (write answer below and in the
box on the screen)
6. Insertions and Deletions
Challenge: Make an Insertion that causes a Frameshift
a. Synthesize the un-mutated protein, and take a snapshot.
b. Reset the system. Make an insertion mutation somewhere in the
first half of the sequence. You should see a frame-shift occur.
c. Synthesize your mutant protein by pressing the transcribe and
translate buttons. Press the pause button as soon as the last amino
acid is produced.
d. Press the “snapshot” button and type “insertion” in the box.
e. How do insertion mutations have a bigger effect on the protein than
substitutions?
7. The Effect of Mutations
a. How can mutations be neutral?
b. Which types of mutations, among the ones you created in this
activity, are more likely to be lethal?
_________________________________________________
Why?____________________________________________________
________________________________________________________
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