Mutations are changes in the genetic material of a cell that can result in changes to proteins. There are three main types of point mutations: silent mutations which do not change the protein, missense mutations which change one amino acid in the protein, and nonsense mutations which result in a premature stop in translation. Frameshift mutations occur when nucleotides are inserted or deleted, changing the reading frame and resulting in a completely different protein sequence with no stop codon. Mutations can occur during DNA replication due to errors or exposure to mutagens like UV light, chemicals, or intercalating dyes.

1. MUTATION AND
PROTEINS

2. WARM-UP
• Finish the Pre-lab on your Enzyme Lab handout.
• Announcements
• - 8 days until DNA Exam
• - US Geological Survey Paid Internship Program
• - Guest Speaker Tomorrow
• - Return the UV Light Box – 5 people
• - Dissecting Scopes from Jay Vavra – 2 people

3. Mutations
Mutations are changes in the genetic material of a cell

4. Mutations
Point mutations are changes in one base pair of a gene
a. What would the series of nucleotides in mRNA transcribed
from this strand be?
AUG UGG GAG CAU UGA
a. List the codons from the mRNA coded for by this series of
DNA?
b. If the sequence of DNA nucleotides above is a complete
gene that codes for a protein, what are the amino acids that
make this protein?
Start(Met) Trp Glu His Stop

5. Mutations
• How are the proteins for each DNA sequence different?
They’ re not
• This is an example of point mutation called a silent
mutation

6. Mutations
• What would the series of nucleotides in mRNA transcribed from this
strand be?
AUG UGG GUA CAU UGA
• List the codons from the mRNA coded for by this series of DNA?
• If the sequence of DNA nucleotides above is a complete gene that
codes for a protein, what are the amino acids that make this protein?
Start(Met) Trp Val His Stop
• How are the proteins for each DNA sequence different?
Glu into Val
• This is an example of a type of point mutation called a missense
• The last type of point mutation is called a nonsense
Sickle Cell Anemia:
http://www.pbs.org/wgbh/evolution/library/01/2/l_012_02.html

7. Mutations
A frame shift mutation is when a certain number of nucleotides are
inserted or deleted in the reading frame of a gene
…what would the RNA sequence of the original strand and the mutated
strand be?
AUGGGGAACAUUGA
If the sequence of DNA nucleotides above is a complete gene that
codes for a protein, what are the amino acids that make this protein?
Start-Gly-Asn-Ile- vs. Start Trp Glu His Stop
How are the proteins for each DNA sequence different?
Every single protein is different and there is no stop codon
This type of frameshift mutation is called a(n) deletion

8. How do Mutations occur
DNA replication
Mutagens
can be physical or chemical
- physical: UV or Xrays
- chemical: imidazole or EtBr (ethidium bromide)