Download Reading DNA and Mutations

Reading DNA and Mutations
Activity
1.
2.
3.
4.
5.
Split into 2 groups
Take a big piece of paper
Record your DNA sequence
Make Amino Acids
Make Proteins
DNA  Amino Acid 
Protein
A DNA SENTENCE!
• Here's the sequence:
GCATGCTGCGAAACTTTGGCTGA
Separate into Codons
• First, try separating the sequence into three-letter
codons.
Codons
• You can do this three ways:
GCA TGC TGC GAA ACT TTG GCT GAG CAT GCT
GCG AAA CTT TGG CTG AGC ATG CTG CGA
AAC TTT GGC TGA
Where did you start?
• How can you tell which of the three codon
"reading frames" is the correct one?
• All genes begin with the three-letter sequence
"ATG," which encodes the amino acid
methionine (Met). Therefore, the correct
reading frame will contain the codon "ATG."
Amino Acids
• Review "What is the Universal Genetic Code?"
on the right side of this page.
• Then use the Code, shown below, to
determine the amino acid sequence
• Once you've translated the DNA sequence, go
back and try to make each of the mutations
discussed at right.
Order
•
•
•
•
DNA
Codons (start at Met – ATG)
Amino Acids
Protein
Mutation Types
Point mutations are single
nucleotide base changes in a
gene's DNA sequence. :
Insertion mutations and deletion
mutations add or remove one or
more DNA bases.
This type of mutation can change the
gene's protein product in the
following ways:
• Missense mutations are point
mutations that result in a single
amino acid change within the
protein.
• Nonsense mutations are point
mutations that create a premature
"translation stop signal" (or "stop"
codon), causing the protein to be
shortened.
• Silent mutations are point
mutations that do not cause
amino acid changes within the
protein.
• Insertion and deletion mutations
cause frameshift mutations, which
change the grouping of nucleotide
bases into codons.
• This results in a shift of "reading
frame" during protein translation.
MUTATE A DNA SENTENCE!
• It's time to try your hand at mutating
a DNA sequence.
• Here's the sequence:
GCATGCTGCGAAACTTTGGCTGA
Mutation Effects
Missense mutation:
• What does a missense mutation look like?
• How does it change the amino acid sequence?
Nonsense Mutation:
• What does a nonsense mutation look like?
• How does it change the amino acid sequence?
Frame Shift:
• You can make more than one frameshift mutation.
• What do they look like?
• How do they change the amino acid sequence?
• Notice how a single amino acid can be encoded by a
number of different codons.
• What are some examples of silent mutations in the DNA
sequence?