Name: ______________________________________________________ Period: _____
Gene Mutations Activity
I.
Types of Mutations
A __________________ is a change in the DNA
1) Chromosomal Mutations – affect ______________genes ex. Down syndrome
2) ***Gene mutations- affect a _______________gene – smaller effect
i. Frameshift Mutations
1. Insertion – a new base is _______________ to a codon
INSERT A “G” 
ex. AUG UAC GGU
AUG GUAC GGU
AUG GUA CGG U
2. Deletion – a base is ______________ from a codon
REMOVE THE “U” 
ex. AUG
UAC GGU
AUG
AC GGU
AUG
ACG
GU
ii. Point Mutation (base substitution) one base is _________________ for another
1. Missense- a _______________ amino acid is coded for
Ex. UUU is Phenylalanine
Ex. UUA is Leucine
2. Silent – _________________ in the amino acid sequence
Ex. CCC is Proline
Ex. CCG is Proline
3. Nonsense- _____________ codon before gene is done being translated (Stop codons are
UAA, UAG, UGA)
Ex. UGG is Tryptophan but UGA is STOP
What does it mean to “shift” the reading frame? Let’s look at an analogy to sentences instead of DNA.
Frameshift Mutation: Insertion
Insert an “S” here 
“DNA” Sequence Sentence: THE BOY CUT HIS LIP AND ATE THE HOT DOG
Affect of Insertion:
____ ____ ____ ____ ___ ____ ____ ____ ____ ____
Frameshift Mutation: Deletion
Delete the D!
“DNA” Sequence Sentence: THE BOY CUT HIS LIP AND ATE THE HOT DOG
↙
Affect of Deletion:
____ ____ ____ ___ ___ ____ ____ ____ ____ ____
--------------------------------------------------------------------------------------------------------------------------------------Now use a real DNA sequence and transcribe and translate it into the correct amino acids.
Frameshift Mutation: Insertion
Insert a G
CGA TCT CAG GAG CCT ATA ATC
Original DNA
TAC GGA
Insertion Mutation
____ ____
____
____ ____ ____ ____ ____ ____
Mutated mRNA
____ ____
____
____ ____ ____ ____ ____ ____
Mutated Amino Acids
____ ____
____
____ ____ ____ ____ ____ ____
Original Amino Acid
Sequence
Met
Ala
Arg
Pro
Val
Leu
Gly
Try
STOP
Frameshift Mutation: Deletion
Original DNA
Delete the C
TAC GGA CGA TCT CAG GAG CCT ATA ATC
Deletion Mutation
____
____
____
____ ____ ____ ____ ____
____
Mutated mRNA
____
____
____
____ ____ ____ ____ ____
____
Mutated Amino Acids
____ ____
____
____ ____ ____ ____ ____
____
Original Amino Acid
Sequence
Met
Ala
Pro
Arg Val
Leu
Gly Try STOP
Point Mutation (substitution): Missense
Ex.
GAC → TAC
GAC → GAG
Replace the C with a G
Original DNA
TAC CAT GCA GAT CTG GCC CAG TTC ATC
Transversion Mutation ____
____
____
____ ____ ____ ____ ____ ____
Mutated mRNA
____
____
____
____ ____ ____ ____ ____ ____
Mutated Amino Acids ____
____
____
____ ____ ____ ____ ____ ____
Original Amino Acid
Sequence
Val
Arg
Leu Asp A Arg
Met
Val
Lys
STOP
Point Mutation (substitution): Silent
Change the whole codon to TCC
Original DNA
TAC CAT
TCT
CGG
TGT
AAA
AGG
GCG
ATT
Silent Mutation
____
____
____
____
____
____
____
____
____
Mutated mRNA
____
____
____
____
____
____
____
____
____
Mutated Amino Acids
____
____
____
____
____
____
____
____
____
Original Amino Acid
Sequence
Met
Val
Arg
Ala
Thr
Phe
Ser
Arg
STOP
Point Mutation (substitution): Nonsense
Ex.
DNA codon
mRNA codon
Amino Acid
Original DNA
ATA → ATT
UAU → UAA
Tyr → STOP
Change the whole codon to ATT
TAC GGT AAT CAA ATA GAA
CCT
GAG ACT
Nonsense Mutation
____ ____
____
____ ____
____
____ ____
____
Mutated mRNA
____ ____
____
____ ____
____
____ ____
____
Mutated Amino Acids
____ ____
____
____ ____
____ ____
Original Amino Acid
Sequence
Met
Leu
Val
Pro
Tyr
Leu
Gly
____
Leu
____
STOP
Analysis Questions:
1. Explain the difference between a frameshift mutation and a point mutation.
2. Which type of mutation, a frameshift or a point mutation, has more effect on the organism? Why?
3. Usually a frameshift mutation results in making a protein that does not work. Why do you think
mutated proteins might not work?
4. Which type of point mutation would not hurt the organism? Why?
5. Which type of point mutation would have the greatest affect on the organism? Why?
6. Which type of point mutation would most likely cause only one amino acid to change?