Name: ____________________________________________ Period: ________ Date:
MUTATIONS
There are several types of mutation:
 DELETION (a base is lost/deleted)
 INSERTION (an extra base is added/inserted)
--- Deletion & insertion may cause what’s called a FRAMESHIFT mutation,
meaning the reading “frame" changes, thus changing the amino acid sequence
from this point forward
 POINT MUTATION/SUBSTITUTION (one base is substituted for another)
--- If a substitution changes the amino acid, it’s called a MISSENSE mutation
--- If a substitution does not change the amino acid, it’s called a SILENT mutation
--- If a substitution changes the amino acid to a “stop,” it’s called a NONSENSE mutation
Complete the boxes below. Classify each as Deletion, Insertion or Substitution AND as either
frameshift, missense, silent or nonsense (Hint: Deletion & Insertion will always be frameshift).
T A C A C C T T G G C G A C G A C T…
Original DNA Sequence:
mRNA Sequence:
Amino Acid Sequence:
__________________________________________________
Mutated DNA Sequence #1
T A C A T C T T G G C G A C G A C T…
What’s the mRNA sequence?
(Circle the changed codon(s))
What will be the amino acid sequence?
Will there likely be effects?
Mutated DNA Sequence #2
What type of mutation is this? ________________________________
T A C G A C C T T G G C G A C G A C T…
What’s the mRNA sequence?
(Circle the changed codon(s))
What will be the amino acid sequence?
Will there likely be effects?
Mutated DNA Sequence #3
What type of mutation is this? ________________________________
T A C A C C T T A G C G A C G A C T…
What’s the mRNA sequence?
(Circle the changed codon(s))
What will be the amino acid sequence?
Will there likely be effects?
Mutated DNA Sequence #4
What type of mutation is this? ________________________________
T A C A C C T T G G C G A C T A C T…
What’s the mRNA sequence?
(Circle the changed codons(s))
What will be the amino acid sequence?
Will there likely be effects?
Mutated DNA Sequence #5
What type of mutation is this? _________________________________
T A C A C C T T G G C G A C C A C T…
What’s the mRNA sequence?
(Circle the changed codon(s))
What will be the amino acid sequence?
Will there likely be effects?
\
What type of mutation is this? _________________________________
Mutated DNA Sequence #6
T A C A C C T T G G G A C G A C T…
What’s the mRNA sequence?
(Circle the changed codon(s))
What will be the amino acid sequence?
Will there likely be effects?
What type of mutation is this? _________________________________
Answer all parts of the following questions.
1.
Pick 2 genetic mutations from the introduction and answer the following: What do they have in common? How are they
different? Show an example of each. ________________________
Example 1
Example 2
_______________________________________________________
_______________________________________________________
_______________________________________________________
_______________________________________________________
2.
A geneticist found that a particular mutation had no effect on the protein coded by a gene. What do you think is the most likely
type of mutation in this gene?_______________ Why? __________________________________________________________
________________________________________________________________________________________________________
3.
Using the amino acid chart name one amino acid that has more than one codon.________________________ Name an amino
acid that has only one codon. ________________________________
4.
Look at the following sequence: THE FAT CAT ATE THE RAT. Delete the first H and regroup the letters in groups of three,
write out the new sentence ________________________________________________________________ Does the sentence
still make sense?______ What type of mutation is this an example of?_________________________
5.
Given the following three mRNA segments, circle the two that code for the same amino acid chain. Support your answer by
sequencing the RNA into amino acids.
i.
AGU UUA GCA ACG AGA UCA  Amino Acids: _________________________________________________________
ii.
UCG CUA GCG ACC AGU UCA  Amino Acids: __________________________________________________________
iii.
AGC CUC GCC ACU CGU AGU  Amino Acids: _________________________________________________________
6.
7.
You have a DNA sequence that codes for a protein and is 105 nucleotides long. A frameshift mutation (insertion) occurs after the
84th base.
Show your work:
a. How many total amino acids are being coded for? ___________
b.
How many amino acids will remain the same? ______________
c.
How many amino acids might be changed? ________________
You have a DNA sequence that codes for a protein and is 99 nucleotides long. A frameshift mutation (deletion) occurs after the
75th base.
Show your work:
a. How many total amino acids are being coded for? ___________
b. How many amino acids will remain the same? ______________
c.
8.
How many amino acids might be changed? ________________
You have a DNA sequence that codes for a protein and is 144 nucleotides long. A frameshift mutation (insertion) occurs after the
114th base.
Show your work:
a. How many total amino acids are being coded for? ___________
b.
How many amino acids will remain the same? ______________
c.
How many amino acids might be changed? ________________