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Mutation Lab Handout
Brains
Mutations by
An logy
An introduction to
Point Mutation
After this lesson students will be able to
identify three types of point mutation:
substitution, insertion, and deletion;
and predict & explain the effect of these
genetic mutations coding for
mRNA on protein synthesis.
Language Arts question:
What is an
ANALOGY?
INSTRUCTIONS
Every three bases on the mRNA codes for an amino
acid. Every three bases of our “Secret PseudoProtein Code” codes for a letter or punctuation mark.
Since our “Secret Pseudo-Protein Code” is more
familiar, we will use it to examine mutations.
Remember the same rules hold for both codes:
1.All messages must begin with START.
2.There are no spaces between three letter words;
one simply counts every three letters.
1. Original message:
|A
U
G
|G
H
U
G
|U
a
U
C
|A
l
C
U
|A
l
C
U
|G
o
C
A
|U
!
A
A
|
A
|
Point substitution mutation:
|A
U
G
|G
H
U
G
|A
e
U
C
|A
l
C
U
|A
l
C
U
|G
o
C
A
|U
!
A
What was the effect of this mutation?
One letter was changed.
If this had been an mRNA coding for a protein, what would
have been changed?
One amino acid was changed.
2. Original message:
|A
U
G
|A
m
C
A
|U
i
C
A
|
x
U
G
G
|A
t
G
A
|G
u
r
e
A
U
|
C
A
A
|
A
U
U
C
|
A
A
A
|
U
C
C
Point deletion mutation:
m
i
.
| A U G |A C A | U C A| U G A | G A G | A
What was the effect of this mutation?
If this had been an mRNA coding for a protein, what would
have been changed?
Only part of protein synthesized.
Answer this:
Did the size of
this mutation’s
EFFECT surprise
you?
3. Original message:
|A
U
G
|G
W
A
G
|U
h
C
U
|
a
U
U
C
|A
t
A
A
|U
?
A
G
|
U
A
G
|
A
G
G
|
G
|G
Point insertion mutation:
|A
U
G
|G
W
A
G
|U
h
C
U
|
a
U
U
C
|A
s
A
U
|A
U
W
g
F
A
|
G
U
A
|
G
A
What was the effect of this mutation?
If this had been an mRNA coding for a protein, what would have been
changed?
Longer, but nonfunctioning, protein
4.
Original message:
P
|A
U
G
|U
A
r
U
|C
A
o
A
|
G
t
e
n
i
C
A
|A
A
A
|A
U
C
|
U
C
A
|
G
C
U
|
C
A
|A
A
A
|A
U
C
|U
C
A
|G
C
U
|
Point substitution mutation:
|G
U
G
|U
A
U
|C
A
A
|
G
What was the effect of this mutation?
If this had been an mRNA coding for a protein, what would have been
changed?
NO protein because no start (met)
5.
Original message:
L
|A
U
G
|C
C
a
G
|U
U
t
C
|
A
A
e
A
|A
U
r
C
|C
A
.
A
|U
G
A
|G
C
U
|
A
|
C
U
|
Point substitution mutation:
L
|A
U
G
|C
C
a
G
|U
U
t
C
|
A
G
e
A
|A
U
r
C
|C
A
.
A
|U
G
G
What was the effect of this mutation?
If this had been an mRNA coding for a protein, what would have been
changed?
NO change in protein
Redundant:
• Definition: excess,
wordy
• The code is redundant;
there is more than one
way to code for the
same amino acid.
6. During this activity you modeled
protein synthesis using mRNA.
But where did the mutation
originally occur?
The mutation was actually
in the DNA base-pair order.
7. What is a mutation?
A mutation is a
change in base order of DNA
in a cell’s chromosome.
8. How can a change in the DNA cause
a change in an organism’s protein?
Change in DNA causes
change in mRNA causes
changes in order, &/or number, of
amino acids in the protein.
9. Do all mutations in the DNA coding
for mRNA cause a change in an
organism? Why or why not?
NO!
Code is redundant:
Most amino acids (& STOP)
have more than one code.
Some changes in base order
do NOT cause changes in
amino acids .
10. Are mutations helpful or harmful?
Some mutations can be helpful .
Disease resistance
Hallo!  Hello!
Some mutations can be harmful .
Cancer
What?  WhaSFgW
Many mutations are often neutral .
Little/no change
Later.  Later.
10. Are mutations helpful or harmful?
Can be helpful , harmful, neutral.
Whether a mutation is good or
bad is often a function of the
environment.
Sickle cell anemia
 Stress  blood cells change shape
 pain, strokes, etc.
 Can’t catch malaria!
Got name?