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10.16 Describe the major types of mutations, causes of mutations, and
possible consequences.

Causes:
o toxic chemicals: carcinogen
o radiation: sun (UV), X-ray machines, radioactive isotopes (U235)
The environment of a cell has changed. Let’s
say that there is suddenly lactose sugar
present! The cell must make loads of lactase
right away.
Name some ways that the cell can gear up
production of lactase quickly.
To illustrate the impact that mutations can
have on a living thing, some made-up
numbers are being applied that are relatively
correct (only).

Make many (100) mRNA molecules.

Each mRNA molecule can hold many
ribosomes (a polyribosomal system)
and is translated ten times (10).

Make many (1,000) lactase enzymes.
1.
If a mutation occurs while one ribosome
is translating to make a polypeptide,
how many of the 1,000 proteins is
affected? ___%
2.
If a mutation occurs while a mRNA is
being transcribed, how many of the
1,000 proteins is affected? ___%
3.
If a mutation occurs while the DNA is
being replicated, how many of the 1,000
proteins is affected? ___%
Answers:
1.) 1/1,000 =.001 OR
2.) 10/1,000 OR 1/100 = .01 OR
3.) all
Mrs. Loyd 
[email protected]
0.1%
10%
100%
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Unit 5 DNA to Protein
LT5. Mutations
Workshop Review
LT5a I can define what a mutation is and how it affects proteins.
Define mutation.
Translate the mRNA into amino acids and analyze the result.
Explain how the following mutations affect the amino acid sequence of the polypeptide (protein).
Type of
Mutation
Substitution of
one DNA base for
another
Normal mRNA and A.A.’s
AUG-UAC-UUU-GGC-GAA
Met - Tyr - Phe - Gly - Glu
AUG-UAC-UUU-GGA-GAA
AUG-UAC-UUU-AGC-GAA
AUG-UAG-UUU-GGC-GAA
Insertions or
deletions of DNA
nucleo-tides cause
a frame-shift
mutation.
AUG-UAC-UU_ -GGC-GAA
Effect
Silent mutations result in ____________
_______ due to the wobble effect.
Missense mutation results in ________
________________________________.This
may or may not change the shape and
function of the protein.
Nonsense mutations change an amino acid
codon to_____________________.
Frame-shift mutations can shift the reading
frame resulting in
Use either code diagram. The round one starts in the middle and works outward.
Answers on the back.
Mrs. Loyd 
[email protected]
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Lab Stn #1
ANSWER:
Definition: Mutations are changes in the DNA base sequence, caused by errors in DNA replication or
recombination (like crossing over) or by mutagens (like radiation or toxic chemicals). Substituting,
deleting, or inserting nucleotides in a gene has varying effects on the polypeptide and organism.
Please do not move
the question to a
different lab station.
Translate the mRNA into amino acids and analyze the result.
Explain how the following mutations affect the amino acid sequence of the polypeptide (protein).
Type of
Mutation
Substitution of
one DNA base for
another
Examples
Normal mRNA and A.A.’s
AUG-UAC-UUU-GGC-GAA
Met - Tyr - Phe - Gly - Glu
AUG-UAC-UUU-GGA-GAA
AUG-UAC-UUU-AGC-GAA
AUG-UAG-UUU-GGC-GAA
Insertions or
deletions of DNA
nucleotides cause
a frame-shift
mutation.
AUG-UAC-UU_ -GGC-GAA
Mrs. Loyd 
[email protected]
Effect
Silent mutations result in no change to amino
acids due to the wobble effect.
Missense mutation results in a trade of one
amino acid for a different one. This may or
may not change the shape and function of the
protein.
Nonsense mutations change an amino acid
codon to a stop codon.
Frame-shift mutations can shift the reading
frame resulting in altered triplet groups and
greatly change the amino acid sequence or
put in a very premature stop codon. This
would, most likely, render the protein
useless.
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